diff --git a/PhysicsPackages/eigenPhysicsPackage_class.f90 b/PhysicsPackages/eigenPhysicsPackage_class.f90
index aa89111c1..d67603e8a 100644
--- a/PhysicsPackages/eigenPhysicsPackage_class.f90
+++ b/PhysicsPackages/eigenPhysicsPackage_class.f90
@@ -323,7 +323,7 @@ subroutine collectResults(self)
     type(outputFile)                          :: out
     character(nameLen)                        :: name
 
-    call out % init(self % outputFormat)
+    call out % init(self % outputFormat, filename=self % outputFile)
 
     name = 'seed'
     call out % printValue(self % pRNG % getSeed(),name)
@@ -359,8 +359,6 @@ subroutine collectResults(self)
     call self % activeTally % print(out)
     call out % endBlock()
 
-    call out % writeToFile(self % outputFile)
-
   end subroutine collectResults
 
 
diff --git a/PhysicsPackages/fixedSourcePhysicsPackage_class.f90 b/PhysicsPackages/fixedSourcePhysicsPackage_class.f90
index cd200cdb6..792d11d38 100644
--- a/PhysicsPackages/fixedSourcePhysicsPackage_class.f90
+++ b/PhysicsPackages/fixedSourcePhysicsPackage_class.f90
@@ -266,7 +266,7 @@ subroutine collectResults(self)
     type(outputFile)                                :: out
     character(nameLen)                              :: name
 
-    call out % init(self % outputFormat)
+    call out % init(self % outputFormat, filename=self % outputFile)
 
     name = 'seed'
     call out % printValue(self % pRNG % getSeed(),name)
@@ -287,8 +287,6 @@ subroutine collectResults(self)
     ! Print tally
     call self % tally % print(out)
 
-    call out % writeToFile(self % outputFile)
-
   end subroutine collectResults
 
 
diff --git a/UserInterface/fileOutput/CMakeLists.txt b/UserInterface/fileOutput/CMakeLists.txt
index bf913adf4..3ad697235 100644
--- a/UserInterface/fileOutput/CMakeLists.txt
+++ b/UserInterface/fileOutput/CMakeLists.txt
@@ -4,6 +4,7 @@ add_sources( ./outputFile_class.f90
              ./asciiOutputFactory_func.f90
              ./asciiMATLAB_class.f90
              ./asciiJSON_class.f90
-             ./dummyPrinter_class.f90)
+             ./dummyPrinter_class.f90
+             ./delayedStream_class.f90)
 
 add_unit_tests (./Tests/outputFile_test.f90)
diff --git a/UserInterface/fileOutput/asciiJSON_class.f90 b/UserInterface/fileOutput/asciiJSON_class.f90
index 18ddf36eb..4fd6fa66c 100644
--- a/UserInterface/fileOutput/asciiJSON_class.f90
+++ b/UserInterface/fileOutput/asciiJSON_class.f90
@@ -21,7 +21,7 @@ module asciiJSON_class
   !! There is indentation for each block and entry, but long multi-dimensional (N-D) arrays
   !! are printed on a single line. Also N-D arrays are represented as a JSON array of arrays.
   !!
-  !! JSON output is fairly standard so it can be easlily read into Python and other enviroments
+  !! JSON output is fairly standard so it can be easily read into Python and other environments
   !!
   !! TODO:
   !!  Currently there is a dirty fix to remove commas at the end of a block, which requires to
@@ -39,7 +39,6 @@ module asciiJSON_class
   !!
   type, public, extends(asciiOutput) :: asciiJSON
     private
-    type(charTape)    :: output
     integer(shortInt) :: ind_lvl = 0
 
     integer(shortInt), dimension(:), allocatable :: shapeBuffer
@@ -49,8 +48,8 @@ module asciiJSON_class
 
   contains
     procedure :: init
+    procedure :: endFile
     procedure :: extension
-    procedure :: writeToFile
 
     procedure :: startBlock
     procedure :: endBlock
@@ -71,51 +70,43 @@ subroutine init(self)
     class(asciiJSON), intent(inout) :: self
 
     ! Add the initial bracket
-    call self % output % append( "{" // NEWLINE)
+    call self % append( "{" // NEWLINE)
     self % ind_lvl = 1
 
   end subroutine init
 
   !!
-  !! Return approperiate extension for the file
+  !! Finalise the printer
   !!
   !! See asciiOutput_inter for details
   !!
-  pure function extension(self) result(str)
-    class(asciiJSON), intent(in) :: self
-    character(:), allocatable    :: str
-
-    str = 'json'
-
-  end function extension
-
-  !!
-  !! Print the output to the given unit
-  !!
-  !! See asciiOutput_inter for details
-  !!
-  subroutine writeToFile(self, unit)
+  subroutine endFile(self)
     class(asciiJSON), intent(inout) :: self
-    integer(shortInt), intent(in)   :: unit
-    character(:),allocatable        :: form
 
     ! Dirty fix
     ! Remove comma from the last entry by rewind
     ! Need to check that the character is a comma to avoid removing { when there is an empty block
     ! TODO: Find better way. Will clash with any proper stream output
-    if (self % output % get(self % output % length() - 1) == ",") then
-      call self % output % cut(2)
-      call self % output % append(NEWLINE)
+    if (self % peek(2) == ",") then
+      call self % cut(2)
+      call self % append(NEWLINE)
     end if
+    call self % append("}" // NEWLINE)
 
-    ! Close the file
-    call self % output % append("}")
+  end subroutine endFile
 
-    form = '(A' // numToChar(self % output % length()) // ')'
+  !!
+  !! Return appropriate extension for the file
+  !!
+  !! See asciiOutput_inter for details
+  !!
+  pure function extension(self) result(str)
+    class(asciiJSON), intent(in) :: self
+    character(:), allocatable    :: str
 
-    write(unit,form) self % output % expose()
+    str = 'json'
 
-  end subroutine writeToFile
+  end function extension
 
   !!
   !! Change state to writing new block with "name"
@@ -127,10 +118,10 @@ subroutine startBlock(self, name)
     character(nameLen), intent(in)  :: name
 
     ! Write indentation
-    call self % output % append(repeat(BLANK, self % ind_lvl * IND_SIZE))
+    call self % append(repeat(BLANK, self % ind_lvl * IND_SIZE))
 
     ! Open new block and increase indentation
-    call self % output % append(QUOTE // trim(name) // QUOTE // ":" // "{" // NEWLINE)
+    call self % append(QUOTE // trim(name) // QUOTE // ":" // "{" // NEWLINE)
     self % ind_lvl = self % ind_lvl + 1
 
   end subroutine startBlock
@@ -147,17 +138,17 @@ subroutine endBlock(self)
     ! Remove comma from the last entry by rewind
     ! Need to check that the character is a comma to avoid removing { when there is an empty block
     ! TODO: Find better way. Will clash with any proper stream output
-    if (self % output % get(self % output % length() - 1) == ",") then
-      call self % output % cut(2)
-      call self % output % append(NEWLINE)
+    if (self % peek(2)  == ",") then
+      call self % cut(2)
+      call self % append(NEWLINE)
     end if
 
     ! Decrease and write indentation
     self % ind_lvl = self % ind_lvl - 1
-    call self % output % append(repeat(BLANK, self % ind_lvl * IND_SIZE))
+    call self % append(repeat(BLANK, self % ind_lvl * IND_SIZE))
 
     ! Close the block
-    call self % output % append("}" // ","// NEWLINE)
+    call self % append("}" // ","// NEWLINE)
 
   end subroutine endBlock
 
@@ -171,10 +162,10 @@ subroutine startEntry(self, name)
     character(*), intent(in)        :: name
 
     ! Print indentation
-    call self % output % append(repeat(BLANK, self % ind_lvl * IND_SIZE))
+    call self % append(repeat(BLANK, self % ind_lvl * IND_SIZE))
 
     ! Write the name
-    call self % output % append(QUOTE // trim(name) // QUOTE // ":")
+    call self % append(QUOTE // trim(name) // QUOTE // ":")
 
   end subroutine startEntry
 
@@ -188,7 +179,7 @@ subroutine endEntry(self)
 
     ! End with NEWLINE
     ! Comma will be written together with a number/char
-    call self % output % append(NEWLINE)
+    call self % append(NEWLINE)
 
   end subroutine endEntry
 
@@ -235,12 +226,12 @@ subroutine printNum(self, val)
       mul = 1
       do i = 1, size(self % shapeBuffer)
         mul = mul * self % shapeBuffer(i)
-        if (modulo(self % count, mul) == 0) call self % output % append("[")
+        if (modulo(self % count, mul) == 0) call self % append("[")
       end do
     end if
 
     ! Print the number
-    call self % output % append(val)
+    call self % append(val)
 
     if (self % in_array) then
       ! Append the count
@@ -250,12 +241,12 @@ subroutine printNum(self, val)
       mul = 1
       do i = 1, size(self % shapeBuffer)
         mul = mul * self % shapeBuffer(i)
-        if (modulo(self % count, mul) == 0) call self % output % append("]")
+        if (modulo(self % count, mul) == 0) call self % append("]")
       end do
     end if
 
     ! Finish entry with a comma
-    call self % output % append(",")
+    call self % append(",")
 
   end subroutine printNum
 
@@ -274,12 +265,12 @@ subroutine printChar(self, val)
       mul = 1
       do i = 1, size(self % shapeBuffer)
         mul = mul * self % shapeBuffer(i)
-        if (modulo(self % count, mul) == 0) call self % output % append("[")
+        if (modulo(self % count, mul) == 0) call self % append("[")
       end do
     end if
 
     ! Print the character
-    call self % output % append(QUOTE // val // QUOTE)
+    call self % append(QUOTE // val // QUOTE)
 
     if (self % in_array) then
       ! Append the count
@@ -289,12 +280,12 @@ subroutine printChar(self, val)
       mul = 1
       do i = 1, size(self % shapeBuffer)
         mul = mul * self % shapeBuffer(i)
-        if (modulo(self % count, mul) == 0) call self % output % append("]")
+        if (modulo(self % count, mul) == 0) call self % append("]")
       end do
     end if
 
     ! Finish entry with a comma
-    call self % output % append(",")
+    call self % append(",")
 
   end subroutine printChar
 
diff --git a/UserInterface/fileOutput/asciiMATLAB_class.f90 b/UserInterface/fileOutput/asciiMATLAB_class.f90
index eeb232789..b844dc710 100644
--- a/UserInterface/fileOutput/asciiMATLAB_class.f90
+++ b/UserInterface/fileOutput/asciiMATLAB_class.f90
@@ -23,8 +23,8 @@ module asciiMATLAB_class
   !!
   !! Printer for ASCII MATLAB output file
   !!
-  !! Creates a computer-readable matalab ".m" file.
-  !! Despite beeing in ASCII it is not intended for human-readability:
+  !! Creates a computer-readable matlab ".m" file.
+  !! Despite being in ASCII it is not intended for human-readability:
   !!  -> Each entry is a single line.
   !!  -> Furthermore every array is printed as RANK 1 array and a reshape function.
   !!
@@ -40,7 +40,7 @@ module asciiMATLAB_class
   !!   blockLevel     -> Current block level
   !!   output         -> Character that contain the output
   !!   prefix         -> Current prefix for the block
-  !!   shapeBuffer    -> Buffored shape of the current array
+  !!   shapeBuffer    -> Buffered shape of the current array
   !!
   !! Interface:
   !!   asciiOutput Interface
@@ -52,17 +52,14 @@ module asciiMATLAB_class
     type(stackChar)   :: blockNameStack
     integer(shortInt) :: blockLevel = 0
 
-    ! Outputfile
-    type(charTape) :: output
-
     ! Buffers
     type(charTape) :: prefix
     integer(shortInt), dimension(:), allocatable :: shapeBuffer
 
   contains
     procedure :: init
+    procedure :: endFile
     procedure :: extension
-    procedure :: writeToFile
 
     procedure :: startBlock
     procedure :: endBlock
@@ -90,33 +87,29 @@ subroutine init(self)
   end subroutine init
 
   !!
-  !! Return approperiate extension for the file
+  !! Finalise the printer
   !!
   !! See asciiOutput_inter for details
   !!
-  pure function extension(self) result(str)
-    class(asciiMATLAB), intent(in) :: self
-    character(:), allocatable      :: str
+  subroutine endFile(self)
+    class(asciiMATLAB), intent(inout) :: self
 
-    str = 'm'
+    ! Nothing to do
 
-  end function extension
+  end subroutine endFile
 
   !!
-  !! Print the output to the given unit
+  !! Return appropriate extension for the file
   !!
   !! See asciiOutput_inter for details
   !!
-  subroutine writeToFile(self, unit)
-    class(asciiMATLAB), intent(inout) :: self
-    integer(shortInt), intent(in)     :: unit
-    character(:),allocatable          :: form
-
-    form = '(A' // numToChar(self % output % length()) // ')'
+  pure function extension(self) result(str)
+    class(asciiMATLAB), intent(in) :: self
+    character(:), allocatable      :: str
 
-    write(unit,form) self % output % expose()
+    str = 'm'
 
-  end subroutine writeToFile
+  end function extension
 
   !!
   !! Change state to writing new block with "name"
@@ -128,11 +121,6 @@ subroutine startBlock(self, name)
     character(nameLen), intent(in)    :: name
     character(100), parameter :: Here ='startBlock (asciiMATLAB_class.f90)'
 
-    ! Check if state support acction
-    ! if (self % state == IN_ENTRY .or. self % state == IN_ARRAY) then
-    !   call fatalError(Here,'Cannot start writing new block inside entry or array')
-    ! end if
-
     ! Update state - change current prefix
     call self % blockNameStack % push(name)
     call self % prefix % append(trim(name) // '_')
@@ -151,15 +139,6 @@ subroutine endBlock(self)
     integer(shortInt)                 :: N
     character(100), parameter :: Here ='endBlock (asciiMATLAB_class.f90)'
 
-    ! Check if state support acction
-    ! if (self % state == IN_ENTRY .or. self % state == IN_ARRAY) then
-    !   call fatalError(Here,'Cannot end writing new block inside entry or array')
-    ! end if
-    !
-    ! if ( self % blockLevel == 0) then
-    !   call fatalError(Here,'Cannot exit from root block')
-    ! end if
-
     ! Update state - change current prefix
     call self % blockNameStack % pop(temp)
 
@@ -180,17 +159,12 @@ subroutine startEntry(self, name)
     character(*), intent(in)          :: name
     character(100), parameter :: Here ='startEntry (asciiMATLAB_class.f90)'
 
-    ! Check if state support acction
-    ! if (self % state == IN_ENTRY .or. self % state == IN_ARRAY) then
-    !   call fatalError(Here,'Cannot star writing new entry inside entry or array')
-    ! end if
-
     ! Update state
     self % state = IN_ENTRY
 
     ! Write variable name with prefix
-    call self % output % append( trim(self % prefix % expose()) // trim(name))
-    call self % output % append( ' = ')
+    call self % append( trim(self % prefix % expose()) // trim(name))
+    call self % append( ' = ')
 
 
   end subroutine startEntry
@@ -204,16 +178,11 @@ subroutine endEntry(self)
     class(asciiMATLAB), intent(inout) :: self
     character(100), parameter :: Here ='endEntry (asciiMATLAB_class.f90)'
 
-    ! Check if state support acction
-    ! if (self % state == IN_BLOCK .or. self % state == IN_ARRAY) then
-    !   call fatalError(Here,'Cannot finish entry in block or array')
-    ! end if
-
     ! Update state
     self % state = IN_BLOCK
 
     ! Write semicolon and newline
-    call self % output % append( ';' // NEWLINE)
+    call self % append( ';' // NEWLINE)
 
   end subroutine endEntry
 
@@ -227,11 +196,6 @@ subroutine startArray(self, shape)
     integer(shortInt),dimension(:),intent(in) :: shape
     character(100), parameter :: Here ='startArray (asciiMATLAB_class.f90)'
 
-    ! Check if state support acction
-    ! if (self % state /= IN_ENTRY) then
-    !   call fatalError(Here,'Cannot finish entry in block or array')
-    ! end if
-
     ! Update state
     self % state = IN_ARRAY
 
@@ -240,10 +204,10 @@ subroutine startArray(self, shape)
 
     ! Write start of array
     if( size(self % shapeBuffer) == 1) then
-      call self % output % append('[ ')
+      call self % append('[ ')
 
     else
-      call self % output % append('reshape([ ')
+      call self % append('reshape([ ')
 
     end if
 
@@ -259,24 +223,19 @@ subroutine endArray(self)
     integer(shortInt)                 :: i
     character(100), parameter :: Here ='endArray (asciiMATLAB_class.f90)'
 
-    ! Check if state support acction
-    ! if (self % state /= IN_ARRAY) then
-    !   call fatalError(Here,'Cannot finish array inside an entry')
-    ! end if
-
     ! Update state
     self % state = IN_ENTRY
 
     ! Write end of array
-    call self % output % cut(1)
-    call self % output % append(']')
+    call self % cut(1)
+    call self % append(']')
 
     ! Finish reshape function for higher rank arrays
     if( size(self % shapeBuffer) > 1) then
       do i=1,size(self % shapeBuffer)
-        call self % output % append(',' // numToChar(self % shapeBuffer(i)))
+        call self % append(',' // numToChar(self % shapeBuffer(i)))
       end do
-      call self % output % append(')')
+      call self % append(')')
     end if
 
   end subroutine endArray
@@ -292,13 +251,11 @@ subroutine printNum(self, val)
     character(100), parameter :: Here ='printNum (asciiMATLAB_class.f90)'
 
     if(self % state == IN_ARRAY) then
-      call self % output % append(val//',')
+      call self % append(val//',')
 
     else if( self % state == IN_ENTRY) then
-      call self % output % append(val)
+      call self % append(val)
 
-    ! else
-    !   call fatalError(Here,'Cannot print number directly into block')
     end if
 
   end subroutine printNum
@@ -314,13 +271,11 @@ subroutine printChar(self, val)
     character(100), parameter :: Here ='printChar (asciiMATLAB_class.f90)'
 
     if(self % state == IN_ARRAY) then
-      call self % output % append(BRAKET_L // APOS // val // APOS // BRAKET_R // ",")
+      call self % append(BRAKET_L // APOS // val // APOS // BRAKET_R // ",")
 
     else if( self % state == IN_ENTRY) then
-      call self % output % append(BRAKET_L // APOS // val // APOS // BRAKET_R )
+      call self % append(BRAKET_L // APOS // val // APOS // BRAKET_R )
 
-    ! else
-    !   call fatalError(Here,'Cannot print number directly into block')
     end if
 
   end subroutine printChar
diff --git a/UserInterface/fileOutput/asciiOutput_inter.f90 b/UserInterface/fileOutput/asciiOutput_inter.f90
index 0b491d921..e60a7b8b2 100644
--- a/UserInterface/fileOutput/asciiOutput_inter.f90
+++ b/UserInterface/fileOutput/asciiOutput_inter.f90
@@ -1,6 +1,7 @@
 module asciiOutput_inter
 
   use numPrecision
+  use delayedStream_class, only : delayedStream
 
   implicit none
   private
@@ -10,7 +11,7 @@ module asciiOutput_inter
   !!
   !! Allows stream-like output to multiple formats (e.g. MATLAB, CSV, JSON)
   !!
-  !! They recive the sequence of calls from the `outputFile` and conver them to the output file.
+  !! They receive the sequence of calls from the `outputFile` and convert them to the output file.
   !!
   !! Printers do no error checking. It is responsibility of the `outputFile` to ensure that
   !! the sequence is correct.
@@ -21,7 +22,7 @@ module asciiOutput_inter
   !!
   !! Interface:
   !!   init        -> Initialise
-  !!   extension   -> Return file extension approperiate for the format
+  !!   extension   -> Return file extension appropriate for the format
   !!   writeToFile -> Print the output to the provided unit
   !!   startBlock  -> Start new block
   !!   endBlock    -> End a block
@@ -32,10 +33,16 @@ module asciiOutput_inter
   !!
   type, public,abstract :: asciiOutput
     private
+    type(delayedStream) :: stream
   contains
+    procedure                       :: append
+    procedure                       :: cut
+    procedure                       :: peek
+    procedure                       :: close
+    procedure                       :: setUnit
     procedure(init), deferred       :: init
+    procedure(init), deferred       :: endFile
     procedure(extension), deferred  :: extension
-    procedure(writeToFile),deferred :: writeToFile
     procedure(startBlock),deferred  :: startBlock
     procedure(endBlock),deferred    :: endBlock
     procedure(startEntry),deferred  :: startEntry
@@ -61,7 +68,21 @@ subroutine init(self)
     end subroutine init
 
     !!
-    !! Return approperiate extension for the file
+    !! End the file
+    !!
+    !! Format may require to print some characters at the end, so the printer
+    !! needs to be notified that no more data will be provided.
+    !!
+    !! Args:
+    !!  None
+    !!
+    subroutine endFile(self)
+      import :: asciiOutput
+      class(asciiOutput), intent(inout) :: self
+    end subroutine endFile
+
+    !!
+    !! Return appropriate extension for the file
     !!
     !! Must be without any "." Thus "exe" instead of ".exe"!
     !!
@@ -74,19 +95,6 @@ pure function extension(self) result(str)
       character(:), allocatable      :: str
     end function extension
 
-    !!
-    !! Print the output to the given unit
-    !!
-    !! Args:
-    !!  unit [in] -> Unit number of the output
-    !!
-    subroutine writeToFile(self, unit)
-      import :: asciiOutput, &
-                shortInt
-      class(asciiOutput), intent(inout) :: self
-      integer(shortInt), intent(in)     :: unit
-    end subroutine writeToFile
-
     !!
     !! Change state to writing new block with "name"
     !!
@@ -111,7 +119,7 @@ end subroutine endBlock
     !!
     !! Change state to writing a new entry
     !!
-    !! Can recive single value or array next
+    !! Can receive single value or array next
     !!
     !! Args:
     !!   name [in] -> name of the entry
@@ -134,7 +142,7 @@ end subroutine endEntry
     !!
     !! Start writing array with the given shape
     !!
-    !! Name should alrady be provided by "startEntry"
+    !! Name should already be provided by "startEntry"
     !!
     !! Args:
     !!   shape [in] -> Shape of the array (in column-major order)
@@ -183,4 +191,77 @@ subroutine printChar(self, val)
     end subroutine printChar
   end interface
 
+contains
+
+
+    !!
+    !! Write data to the output
+    !!
+    !! Args:
+    !!  text [in] -> Text to be written
+    !!
+    subroutine append(self, text)
+      class(asciiOutput), intent(inout) :: self
+      character(*), intent(in)          :: text
+
+      call self % stream % write(text)
+
+    end subroutine append
+
+    !!
+    !! Remove n characters from the output
+    !!
+    !! Args:
+    !!  n [in] -> Number of characters to be removed
+    !!
+    subroutine cut(self, n)
+      class(asciiOutput), intent(inout) :: self
+      integer, intent(in)               :: n
+
+      call self % stream % cut(n)
+
+    end subroutine cut
+
+    !!
+    !! Get the nth last character from the output
+    !!
+    !! Args:
+    !!   n [in] -> How many characters back to peak
+    !!
+    function peek(self, n) result(c)
+      class(asciiOutput), intent(inout) :: self
+      integer, intent(in)               :: n
+      character(1)                      :: c
+
+      c = self % stream % peek(n)
+
+    end function peek
+
+    !!
+    !! Close the stream
+    !!
+    !! Signals to the output that no more data will be provided, so the
+    !! closing characters can be printed. In addition flushes remaining characters
+    !! in the buffer to the output.
+    !!
+    subroutine close(self)
+      class(asciiOutput), intent(inout) :: self
+
+      call self % endFile()
+      call self % stream % close()
+
+    end subroutine close
+
+    !!
+    !! Set the unit to write to
+    !!
+    subroutine setUnit(self, unit)
+      class(asciiOutput), intent(inout) :: self
+      integer(shortInt), intent(in)     :: unit
+
+      call self % stream % setUnit(unit)
+
+    end subroutine setUnit
+
+
 end module asciiOutput_inter
diff --git a/UserInterface/fileOutput/delayedStream_class.f90 b/UserInterface/fileOutput/delayedStream_class.f90
new file mode 100644
index 000000000..86869fec0
--- /dev/null
+++ b/UserInterface/fileOutput/delayedStream_class.f90
@@ -0,0 +1,185 @@
+module delayedStream_class
+
+  use numPrecision
+  use errors_mod, only : fatalError
+
+  implicit none
+  private
+
+  integer(shortInt), parameter :: MAX_DELAY = 1024
+  integer(shortInt), parameter :: MIN_DELAY = 16
+
+  !!
+  !! Writes characters to a file with a delay to allow for backtracking.
+  !!
+  !! It is required to make writing of output format in stream-like fashion
+  !! easier to implement. For example, in JSON, it allows to backtrack and
+  !! remove trailing comma when closing a JSON dictionary.
+  !!
+  !! NOTE: We need to be careful to check if the file is open before writing
+  !!       to it. Otherwise, we will get an error.
+  !!
+  !! Private Member:
+  !!   unit      -> Unit to which the output file is connected
+  !!   bufferPos -> Position in the buffer
+  !!   buffer    -> Buffer of characters
+  !!
+  !! Interface:
+  !!   write -> Write some characters to the buffer/file
+  !!   cut   -> Remove last N characters from the buffer
+  !!   peek  -> Inspect the Nth last character in the buffer
+  !!   close -> Write all characters remaining in the buffer to the file
+  !!   setUnit -> Set the unit to which the output file is connected
+  !!
+  type, public :: delayedStream
+    private
+    integer(shortInt) :: unit = -8
+    integer(shortInt) :: bufferPos = 0
+    character(MAX_DELAY) :: buffer
+  contains
+    procedure :: write
+    procedure :: cut
+    procedure :: peek
+    procedure :: close
+    procedure :: setUnit
+
+    procedure, private :: flush
+  end type delayedStream
+
+contains
+
+  !!
+  !! Write to a delayed stream
+  !!
+  !! Args:
+  !!   text [in] -> text to write
+  !!
+  subroutine write(self, text)
+    class(delayedStream), intent(inout) :: self
+    character(*), intent(in) :: text
+    integer(shortInt) :: i
+
+    ! Write to buffer
+    do i = 1, len(text)
+      self % bufferPos = self % bufferPos + 1
+      self % buffer(self % bufferPos:self % bufferPos) = text(i:i)
+      if (self % bufferPos == MAX_DELAY) then
+        call flush(self)
+      end if
+    end do
+
+  end subroutine write
+
+  !!
+  !! Remove last characters from a delayed stream
+  !!
+  !! Args:
+  !!  n [in] -> number of characters to remove. Must be less than the MIN_DELAY.
+  !!            If n is larger than the number of characters in buffer, everything is removed.
+  !!
+  subroutine cut(self, n)
+    class(delayedStream), intent(inout) :: self
+    integer(shortInt), intent(in) :: n
+    character(100), parameter :: HERE = "cut (delayedStream_class.f90)"
+
+    if (n > MIN_DELAY) then
+      call fatalError(HERE, "n must be less than MIN_DELAY")
+    end if
+
+    self % bufferPos = max(0, self % bufferPos - n)
+
+  end subroutine cut
+
+  !!
+  !! Inspect the nth last character in the buffer
+  !!
+  !! Args:
+  !!  n [in] -> The number of characters to peek back.
+  !!
+  function peek(self, n) result(c)
+    class(delayedStream), intent(inout) :: self
+    integer(shortInt), intent(in) :: n
+    character(n) :: c
+    character(100), parameter :: HERE = "peek (delayedStream_class.f90)"
+
+    if (n > self % bufferPos) then
+      call fatalError(HERE, "n is larger than the buffer")
+    else
+      c = self % buffer(self % bufferPos - n + 1: self % bufferPos - n + 1)
+    end if
+
+  end function peek
+
+  !!
+  !! Flush contents of the buffer
+  !!
+  subroutine flush(self)
+    class(delayedStream), intent(inout) :: self
+    integer(shortInt) :: to_file
+    logical(defBool) :: isOpen
+
+    ! Do not write anything if the file is not opened
+    inquire(unit=self % unit, opened=isOpen)
+    if (.not. isOpen) then
+      return
+    end if
+
+    ! Do nothing if the buffer is below minimum length
+    if (self % bufferPos <= MIN_DELAY) then
+      return
+    end if
+    to_file = self % bufferPos - MIN_DELAY
+
+    ! Write to file only if it is open
+    if (isOpen) then
+      write(self % unit, "(A)", advance="no") self % buffer(1 : to_file)
+    end if
+
+    self % buffer(1:MIN_DELAY) = self % buffer(to_file + 1 : self % bufferPos)
+
+    self % bufferPos = MIN_DELAY
+
+  end subroutine flush
+
+  !!
+  !! Close the delayed stream
+  !!
+  subroutine close(self)
+    class(delayedStream), intent(inout) :: self
+    logical(defBool) :: isOpen
+
+    ! Do not write anything if the file is not opened
+    inquire(unit=self % unit, opened=isOpen)
+    if (.not. isOpen) then
+      return
+    end if
+
+    ! Does nothing if empty
+    if (self % bufferPos == 0) then
+      return
+    end if
+
+    ! Write the remaining buffer
+    ! Write to file only if it is open
+    if (isOpen) then
+      write(self % unit, "(A)", advance="no") self % buffer(1:self % bufferPos)
+    end if
+    self % bufferPos = 0
+
+  end subroutine close
+
+  !!
+  !! Set the unit to which the output file is connected
+  !!
+  !! Args:
+  !!  unit [in] -> Unit to which the output file is connected. May be opened or not.
+  !!               Both are fine. If it is not opened, nothing will be written to it.
+  subroutine setUnit(self, unit)
+    class(delayedStream), intent(inout) :: self
+    integer(shortInt), intent(in) :: unit
+
+    self % unit = unit
+
+  end subroutine setUnit
+
+end module delayedStream_class
diff --git a/UserInterface/fileOutput/dummyPrinter_class.f90 b/UserInterface/fileOutput/dummyPrinter_class.f90
index 890883d4d..de2f84442 100644
--- a/UserInterface/fileOutput/dummyPrinter_class.f90
+++ b/UserInterface/fileOutput/dummyPrinter_class.f90
@@ -23,8 +23,8 @@ module dummyPrinter_class
 
   contains
     procedure :: init
+    procedure :: endFile
     procedure :: extension
-    procedure :: writeToFile
 
     procedure :: startBlock
     procedure :: endBlock
@@ -52,29 +52,29 @@ subroutine init(self)
   end subroutine init
 
   !!
-  !! Return approperiate extension for the file
+  !! End the file
   !!
   !! See asciiOutput_inter for details
   !!
-  pure function extension(self) result(str)
-    class(dummyPrinter), intent(in) :: self
-    character(:), allocatable    :: str
+  subroutine endFile(self)
+    class(dummyPrinter), intent(inout) :: self
 
-    str = ''
+    ! Nothing to do
 
-  end function extension
+  end subroutine endFile
 
   !!
-  !! Print the output to the given unit
+  !! Return approperiate extension for the file
   !!
   !! See asciiOutput_inter for details
   !!
-  subroutine writeToFile(self, unit)
-    class(dummyPrinter), intent(inout) :: self
-    integer(shortInt), intent(in)      :: unit
+  pure function extension(self) result(str)
+    class(dummyPrinter), intent(in) :: self
+    character(:), allocatable    :: str
 
+    str = ''
 
-  end subroutine writeToFile
+  end function extension
 
   !!
   !! Change state to writing new block with "name"
diff --git a/UserInterface/fileOutput/outputFile_class.f90 b/UserInterface/fileOutput/outputFile_class.f90
index 6585580e0..48fb2011d 100644
--- a/UserInterface/fileOutput/outputFile_class.f90
+++ b/UserInterface/fileOutput/outputFile_class.f90
@@ -1,7 +1,8 @@
 module outputFile_class
 
   use numPrecision
-  use genericProcedures,       only : fatalError, numToChar
+  use errors_mod,              only : fatalError
+  use genericProcedures,       only : numToChar
   use stack_class,             only : stackChar
   use charTape_class,          only : charTape
   use charMap_class,           only : charMap
@@ -28,10 +29,10 @@ module outputFile_class
   !!
   !! Stack to store the dictionaries with occupied entries
   !!
-  !! Note that blocks in outputFile are enumarated from 0
+  !! Note that blocks in outputFile are enumerated from 0
   !! So index in stack is idx = blockLevel + 1
   !!
-  !! Imlementation must be rebust to avoid segmentation errors if outut is used
+  !! Implementation must be robust to avoid segmentation errors if output is used
   !! in incorrect sequence (e.g. closing more blocks then were open)
   !!
   !! Interface
@@ -69,7 +70,7 @@ module outputFile_class
   !!       is called root
   !!  -> Each entry in a block (including sub-blocks) must have a unique name
   !!  -> Each entry is either a raw "Name - Value" pair or an array
-  !!  -> Arrays can have unlimited rank (dimension), but values of the enteries must be given in a
+  !!  -> Arrays can have unlimited rank (dimension), but values of the entries must be given in a
   !!     sequence in a COLUMN-MAJOR ORDER
   !!  -> Arrays can store RESULTS, REALS, INTS or CHARACTERS.
   !!  -> RESULT is a pair of reals. MEAN and STANDARD DEVIATION
@@ -81,14 +82,14 @@ module outputFile_class
   !!
   !! Handling errors:
   !!  If `fatalError` is true (default) then on wrong sequence of calls fatalError will be raised.
-  !!  Otherwise the flag `noErrors` will be set to false and error massege saved in the `errorLog`
+  !!  Otherwise the flag `noErrors` will be set to false and error massage saved in the `errorLog`
   !!
   !! Repeated Names:
-  !!  If name in a block is repeted bahviour is governed by `logNameReuse` function. If `fatalError`
-  !!  is true, the nwarning message is produced. Otherwise error is logged in `errorLog` and
+  !!  If name in a block is repeated behaviour is governed by `logNameReuse` function. If `fatalError`
+  !!  is true, the warning message is produced. Otherwise error is logged in `errorLog` and
   !!  `noErrors` flag set to FALSE.
   !!
-  !! Private Memebers:
+  !! Private Members:
   !!   output      -> Output printer that determines the format
   !!   type        -> Type of the output printer
   !!   fatalErrors -> True (default) makes all errors fatal
@@ -107,8 +108,7 @@ module outputFile_class
   !!
   !! Interface:
   !!   init           -> Initialise the output file with format
-  !!   writeToFile    -> Write the output to a file
-  !!   writeToConsole -> Write the output to the console
+  !!   finalise       -> Finalise the output file. Ensures all data is written.
   !!   reset          -> Discard already written output.
   !!   isValid        -> Return true if no errors were raised since initialisation
   !!   getErrorLog    -> Get the error log
@@ -124,8 +124,10 @@ module outputFile_class
   !!
   type, public :: outputFile
     private
-    class(asciiOutput),allocatable :: output
-    character(nameLen)             :: type
+    class(asciiOutput), allocatable :: output
+    character(nameLen)              :: type
+    character(:), allocatable :: outputFileName
+    integer(shortInt)         :: outputUnit = -97875674 ! Hopefully this does not exist for any internal units
 
     ! Error handling settings
     logical(defBool) :: fatalErrors = .true. ! Enable fatalErrors on wrong logic
@@ -141,7 +143,7 @@ module outputFile_class
     character(nameLen) :: current_array_name = ''
     type(stackChar)    :: block_name_stack
 
-    ! Buffors
+    ! Buffers
     integer(shortInt),dimension(:), allocatable :: shapeBuffer
     type(charMapStack)                          :: usedNames
 
@@ -151,9 +153,8 @@ module outputFile_class
 
   contains
     procedure :: init
-    procedure :: writeToFile
-    procedure :: writeToConsole
     procedure :: reset
+    final :: finalisation
 
     ! Error Handling
     procedure, private :: logError
@@ -210,17 +211,56 @@ module outputFile_class
   !!
   !! Args:
   !!   type [in] -> Character to specify the format of the output file
-  !!   fatalErrors [in] -> Optional. Set on/off fatalErrors oninvalid use of output file.
+  !!   fatalErrors [in] -> Optional. Set on/off fatalErrors on invalid use of output file.
   !!                         Default is ON.
-  !!
-  subroutine init(self, type, fatalErrors)
-    class(outputFile), intent(inout)     :: self
-    character(*),intent(in)              :: type
-    logical(defBool),optional,intent(in) :: fatalErrors
+  !!   filename [in] -> Optional. Set the name of the output file. If none is given no output is
+  !!                    written. Must be given without extension. It will be added automatically
+  !!                    based on the format of the output file.
+  !!
+  subroutine init(self, type, fatalErrors, filename)
+    class(outputFile), intent(inout)      :: self
+    character(*), intent(in)              :: type
+    logical(defBool), optional,intent(in) :: fatalErrors
+    character(*), optional, intent(in)    :: filename
+    integer(shortInt)                     :: error
+    character(99)                         :: errorMsg
+    logical(defBool)                      :: isOpen
+    character(100), parameter             :: Here = "init (outputFile_class.f90)"
 
     self % type = type
     allocate( self % output, source = new_asciiOutput(self % type))
 
+    ! Open file if given
+    ! Otherwise make sure that the unit is not opened
+    if (present(filename)) then
+      ! Because GFotran hates implicit allocation
+      ! It causes buggy warnings to appear in compilation
+      allocate(self % outputFileName, source = trim(filename) // "." // self % output % extension())
+
+      open(newunit = self % outputUnit, &
+           file = self % outputFileName, &
+           status = "replace", &
+           action = "write", &
+           access = "stream", &
+           form = "formatted",&
+           iostat = error, &
+           iomsg = errorMsg)
+
+      ! Catch error
+      if (error /= 0 ) call fatalError(Here, errorMsg)
+    else
+      ! Set unit to some unused, unopened unit
+      ! delayedStream will not write anything if given an unopened file
+      do
+        inquire(self % outputUnit, opened = isOpen)
+        if (.not. isOpen) exit
+        self % outputUnit = self % outputUnit + 1
+      end do
+    end if
+
+    ! Set output unit
+    call self % output % setUnit(self % outputUnit)
+
     ! Initialise name stack
     call self % usedNames % init()
     call self % usedNames % push()
@@ -233,58 +273,36 @@ subroutine init(self, type, fatalErrors)
   end subroutine init
 
   !!
-  !! Dump collected results to file
-  !!
-  !! Writes the output stored in memory to a file
-  !!
-  !! Args:
-  !!   file [in] -> Path to the output file. Must be given WITHOUT extension
-  !!     Approperiate extension will recived from the printer
+  !! Upon the destruction of the object, write the output to file
   !!
-  !! Errors:
-  !!   fatalError if there is a problem opening the file.
-  !!
-  subroutine writeToFile(self, file)
-    class(outPutFile), intent(inout) :: self
-    character(*), intent(in)         :: file
-    integer(shortInt)                :: unitNum
-    integer(shortInt)                :: error
-    character(:), allocatable        :: file_loc
-    character(99)                    :: errorMsg
-    character(100), parameter :: Here = 'writeToFile (outputFile_class.f90)'
-
-    file_loc = trim(file) // "." // self % output % extension()
-
-    ! Open file to write
-    open ( newunit   = unitNum, &
-           file      = file_loc, &
-           action    = 'write', &
-           iostat    = error  , &
-           iomsg     = errorMsg )
-
-    ! Catch error
-    if (error /= 0 ) call fatalError(Here, errorMsg)
-
-    ! Write to file
-    call self % output % writeToFile(unitNum)
-
-    ! Close file
-    close(unitNum)
+  !! NOTE:
+  !!   Being marked `final`(a deconstructor) this subroutine will be normally implicitly called by
+  !!   by the compiler whenever a variable of `type(outputFile)` goes out of scope (e.g. when program
+  !!   execution reaches `end subroutine`, `end function` or `end block` statement. However, the rule in
+  !!   Fortran is that the decostructors are NOT called at the end of the program `end program`. In that case
+  !!   if one uses the output file as a module variable or defines it inside the program block, the `finalisation`
+  !!   must be called explicitly to ensure or data from the buffer is written to the disk
+  !!
+  !!
+  subroutine finalisation(self)
+    type(outputFile), intent(inout) :: self
+    logical(defBool)                :: isOpen
+
+    !! Deallocate the printer
+    !! Needs to be done before closing the file
+    !! So remaining contents of the buffer are flushed
+    if (allocated(self % output)) then
+      call self % output % close()
+      deallocate(self % output)
+    end if
 
-  end subroutine writeToFile
+    inquire(unit = self % outputUnit, opened = isOpen)
 
-  !!
-  !! Print output file to the console (default output)
-  !!
-  !! Args:
-  !!   None
-  !!
-  subroutine writeToConsole(self)
-    class(outputFile), intent(inout) :: self
-
-    call self % output % writeToFile(OUTPUT_UNIT)
+    if (isOpen) then
+      close(self % outputUnit)
+    end if
 
-  end subroutine writeToConsole
+  end subroutine finalisation
 
   !!
   !! Discards all results and sets output file to an initialised state
@@ -296,6 +314,8 @@ subroutine reset(self)
     deallocate(self % output)
     allocate( self % output, source = new_asciiOutput(self % type))
 
+    if (allocated(self % outputFileName)) deallocate(self % outputFileName)
+
     ! Clean error log an reset flag
     call self % errorLog % clean()
     self % noErrors = .true.
@@ -341,10 +361,10 @@ subroutine logError(self, where, what)
   end subroutine logError
 
   !!
-  !! Deal with an event when entry name is resued in a block
+  !! Deal with an event when entry name is reused in a block
   !!
   !! Currently is fatalError is TRUE -> Prints warning to the screen
-  !! If fatalError is False markes error flagto true and appends a log
+  !! If fatalError is False marks error flag to true and appends the log
   !!
   !! Args:
   !!  name [in] -> Name that has been reused
@@ -403,7 +423,7 @@ end function getErrorLog
   !!
   !! Errors:
   !!   Calls logError if:
-  !!     -Called when writting an array
+  !!     -Called when writing an array
   !!   Calls logNameReuse if name is not unique
   !!
   subroutine startBlock(self, name)
@@ -422,7 +442,7 @@ subroutine startBlock(self, name)
     if ( self % arrayType /= NOT_ARRAY) then
       call self % logError(Here,'In block: '// self % current_block_name // &
                                 ' Cannot begin new block: '//name//          &
-                                ' Becouse is writing array: '// self % current_array_name)
+                                ' Because is writing array: '// self % current_array_name)
     end if
 
     ! Update state
@@ -443,7 +463,7 @@ end subroutine startBlock
   !!
   !! Errors:
   !!   Calls logError if:
-  !!     -Called when writting an array
+  !!     -Called when writing an array
   !!     -Tries to end the root block.
   !!
   subroutine endBlock(self)
@@ -454,7 +474,7 @@ subroutine endBlock(self)
     if ( self % arrayType /= NOT_ARRAY) then
       call self % logError(Here,'In block: '// self % current_block_name // &
                                 ' Cannot exit from block: '//                &
-                                ' Becouse is writing array: '// self % current_array_name)
+                                ' Because is writing array: '// self % current_array_name)
     end if
 
     ! Check that is not in root block
@@ -485,7 +505,7 @@ end subroutine endBlock
   !!
   !! Errors:
   !!   Calls logError if:
-  !!     -Called when writting another array
+  !!     -Called when writing another array
   !!     -Shape is invalid
   !!   Calls logNameReuse if name is not unique
   !!
@@ -505,14 +525,14 @@ subroutine startArray(self, name, shape)
     if ( self % arrayType /= NOT_ARRAY) then
       call self % logError(Here,'In block: '// self % current_block_name // &
                                 ' Cannot start new array: '//name//          &
-                                ' Becouse is writing array: '// self % current_array_name)
+                                ' Because is writing array: '// self % current_array_name)
     end if
 
     ! Check whether shape is degenerate
     if (size(shape) == 0 .or. product(shape) == 0) then
       call self % logError(Here,'In block: '// self % current_block_name // &
                                 ' Cannot start new array: '//name//          &
-                                ' Becouse the shape is degenerate')
+                                ' Because the shape is degenerate')
     end if
 
     ! Load shape information into buffer
@@ -524,8 +544,8 @@ subroutine startArray(self, name, shape)
     ! Update State -> Array is present but has undefined type
     self % arrayType = UNDEF_ARRAY
 
-    ! Print begining of new entry
-    ! We don't know the shape of array becouse if has results its rank will increase
+    ! Print beginning of new entry
+    ! We don't know the shape of array because if has results its rank will increase
     call self % output % startEntry(name)
 
   end subroutine startArray
@@ -548,7 +568,7 @@ subroutine endArray(self)
     if(self % arrayTop /= self % arrayLimit) then
       call self % logError(Here, 'Cannot close array: ' // trim(self % current_array_name) // &
                                  ' in block: ' // trim(self % current_block_name)         //  &
-                                 ' Becouse only: '// numToChar(self % arrayTop)          //   &
+                                 ' Because only: '// numToChar(self % arrayTop)          //   &
                                  ' of '// numToChar(self % arrayLimit)//' were provided')
     end if
 
@@ -615,10 +635,10 @@ end subroutine addResult_scalar
   !! Add results to the array
   !!
   !! Args:
-  !!   val [in] -> Array of mean valuse
+  !!   val [in] -> Array of mean values
   !!   std [in] -> Associated standard deviations
   !!
-  !! Erorrs:
+  !! Errors:
   !!   Calls logError if:
   !!     -Called before an array is opened
   !!     -Currently opened array has different type
@@ -632,7 +652,7 @@ subroutine addResult_rank1(self, val, std)
     character(100),parameter :: Here ='addResult_rank1 (outputFile_class.f90)'
 
     N = size(val)
-    if (N /= size(std)) call self % logError(Here,'val and std have diffrent size.')
+    if (N /= size(std)) call self % logError(Here, 'val and std have different size.')
 
     ! Add all individual entries
     do i = 1, N
@@ -1203,7 +1223,7 @@ end subroutine push_charMapStack
   !!   None
   !!
   !! Errors:
-  !!   Poping empty stack does nothing!
+  !!   Popping empty stack does nothing!
   !!
   subroutine pop_charMapStack(self)
     class(charMapStack), intent(inout) :: self
@@ -1218,7 +1238,7 @@ subroutine pop_charMapStack(self)
   end subroutine pop_charMapStack
 
   !!
-  !! Add new entery at the given block level
+  !! Add new entry at the given block level
   !!
   !! Args:
   !!   name [in]  -> Entry name
@@ -1246,7 +1266,7 @@ end subroutine add_charMapStack
   !!   b_lvl [in] -> Block level (idx = b_lvl + 1)
   !!
   !! Result:
-  !!  True if it is. False otherwsie
+  !!  True if it is. False otherwise
   !!
   !! Errors:
   !!   Returns FALSE is b_lvl is out of range
diff --git a/docs/Output.rst b/docs/Output.rst
index 7349deb8d..9d3108e3b 100644
--- a/docs/Output.rst
+++ b/docs/Output.rst
@@ -38,8 +38,9 @@ Writing to an output file in SCONE is done through a series of calls to appropri
   character(nameLen) :: name
   type(outputFile)   :: out
 
-  !! Initialise output by choosing the format
-  call out % init('asciiMatlab')
+  !! Initialise output by choosing the format and output file
+  !! If no file name is provided, the output will not be printed
+  call out % init('asciiMatlab', filename="./path/to/output/without_any_extension")
 
   !! Write an integer of 7
   name = 'int'
@@ -76,9 +77,10 @@ Writing to an output file in SCONE is done through a series of calls to appropri
   !! Same goes for blocks
   call out % endBlock()
 
-  !! When done, we can write output to a file
-  !! Extension will be determined by the format printer
-  call out % writeToFile("./path/to/output/without_any_extension")
+  !! We need to make sure that output file is properly finalised. We can skip
+  !! this line if we are not in a `program` block e.g. in `subroutine` or `function`
+  call out % finalise()
+
 
 The need to write name to a `character(nameLen)` variable before calling the procedure is a quirk
 caused by the fact that the output file expects character of `nameLen` as a variable. If one were to