diff --git a/strutil/random.go b/strutil/random.go
index fe404a017..4b578d3fe 100644
--- a/strutil/random.go
+++ b/strutil/random.go
@@ -1,8 +1,7 @@
 package strutil
 
 import (
-	"encoding/base64"
-	mathRand "math/rand"
+	mRand "math/rand"
 	"time"
 
 	"github.com/gookit/goutil/byteutil"
@@ -11,7 +10,7 @@ import (
 // some consts string chars
 const (
 	Numbers  = "0123456789"
-	HexChars = "0123456789abcdef"
+	HexChars = "0123456789abcdef" // base16
 
 	AlphaBet  = "abcdefghijklmnopqrstuvwxyz"
 	AlphaBet1 = "AaBbCcDdEeFfGgHhIiJjKkLlMmNnOoPpQqRrSsTtUuVvWwXxYyZz"
@@ -19,70 +18,47 @@ const (
 	AlphaNum  = "abcdefghijklmnopqrstuvwxyz0123456789"
 	AlphaNum2 = "abcdefghijklmnopqrstuvwxyz0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"
 	AlphaNum3 = "0123456789AaBbCcDdEeFfGgHhIiJjKkLlMmNnOoPpQqRrSsTtUuVvWwXxYyZz"
-
-	Base62Chars = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
-	Base64Chars = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ+/"
 )
 
 // RandomChars generate give length random chars at `a-z`
 func RandomChars(ln int) string {
 	cs := make([]byte, ln)
+	// UnixNano: 1607400451937462000
+	rn := mRand.New(mRand.NewSource(time.Now().UnixNano()))
+
 	for i := 0; i < ln; i++ {
-		// 1607400451937462000
-		mathRand.Seed(time.Now().UnixNano())
-		idx := mathRand.Intn(25) // 0 - 25
-		cs[i] = AlphaBet[idx]
+		// rand in 0 - 25
+		cs[i] = AlphaBet[rn.Intn(25)]
 	}
-
 	return string(cs)
 }
 
 // RandomCharsV2 generate give length random chars in `0-9a-z`
 func RandomCharsV2(ln int) string {
 	cs := make([]byte, ln)
+	// UnixNano: 1607400451937462000
+	rn := mRand.New(mRand.NewSource(time.Now().UnixNano()))
+
 	for i := 0; i < ln; i++ {
-		// 1607400451937462000
-		mathRand.Seed(time.Now().UnixNano())
-		idx := mathRand.Intn(35) // 0 - 35
-		cs[i] = AlphaNum[idx]
+		// rand in 0 - 35
+		cs[i] = AlphaNum[rn.Intn(35)]
 	}
-
 	return string(cs)
 }
 
 // RandomCharsV3 generate give length random chars in `0-9a-zA-Z`
 func RandomCharsV3(ln int) string {
 	cs := make([]byte, ln)
+	// UnixNano: 1607400451937462000
+	rn := mRand.New(mRand.NewSource(time.Now().UnixNano()))
+
 	for i := 0; i < ln; i++ {
-		// 1607400451937462000
-		mathRand.Seed(time.Now().UnixNano())
-		idx := mathRand.Intn(61) // 0 - 61
-		cs[i] = AlphaNum2[idx]
+		// rand in 0 - 61
+		cs[i] = AlphaNum2[rn.Intn(61)]
 	}
-
 	return string(cs)
 }
 
-// RandomBytes generate
-func RandomBytes(length int) ([]byte, error) {
-	return byteutil.Random(length)
-}
-
-// RandomString generate.
-//
-// Example:
-//
-//		// this will give us a 44 byte, base64 encoded output
-//		token, err := RandomString(32)
-//		if err != nil {
-//	    // Serve an appropriately vague error to the
-//	    // user, but log the details internally.
-//		}
-func RandomString(length int) (string, error) {
-	b, err := RandomBytes(length)
-	return base64.URLEncoding.EncodeToString(b), err
-}
-
 // RandWithTpl generate random string with give template
 func RandWithTpl(n int, letters string) string {
 	if len(letters) == 0 {
@@ -92,10 +68,26 @@ func RandWithTpl(n int, letters string) string {
 	ln := len(letters)
 	cs := make([]byte, n)
 	for i := 0; i < n; i++ {
-		mathRand.Seed(int64(time.Now().Nanosecond()))
-		idx := mathRand.Intn(ln)
-		cs[i] = letters[idx]
+		rn := mRand.New(mRand.NewSource(time.Now().UnixNano()))
+		// rand in 0 - ln
+		cs[i] = letters[rn.Intn(ln)]
 	}
 
 	return byteutil.String(cs)
 }
+
+// RandomString generate.
+//
+// Example:
+//
+//	// this will give us a 44 byte, base64 encoded output
+//	token, err := RandomString(16) // eg: "I7S4yFZddRMxQoudLZZ-eg"
+func RandomString(length int) (string, error) {
+	b, err := RandomBytes(length)
+	return B64URL.EncodeToString(b), err
+}
+
+// RandomBytes generate
+func RandomBytes(length int) ([]byte, error) {
+	return byteutil.Random(length)
+}
diff --git a/strutil/random_test.go b/strutil/random_test.go
index 85c108f75..862b1cfbc 100644
--- a/strutil/random_test.go
+++ b/strutil/random_test.go
@@ -1,7 +1,6 @@
 package strutil_test
 
 import (
-	"encoding/base64"
 	"encoding/hex"
 	"fmt"
 	"math/rand"
@@ -16,27 +15,62 @@ func TestRandomChars(t *testing.T) {
 	for i := 0; i < 10; i++ {
 		str := strutil.RandomChars(4)
 		fmt.Println(str)
-
 		assert.Len(t, str, 4)
 	}
 }
 
 func TestRandomCharsV2(t *testing.T) {
+	keyMp := make(map[string]bool)
 	for i := 0; i < 10; i++ {
-		str := strutil.RandomCharsV2(4)
+		str := strutil.RandomCharsV2(6)
 		fmt.Println(str)
+		assert.Len(t, str, 6)
+		keyMp[str] = true
+	}
+	assert.Len(t, keyMp, 10)
+}
 
-		assert.Len(t, str, 4)
+// https://github.com/gookit/goutil/issues/121
+func TestRandomCharsV2_issues121(t *testing.T) {
+	keyMp := make(map[string]bool)
+
+	for i := 0; i < 10; i++ {
+		str := strutil.RandomCharsV2(32)
+		fmt.Println(str)
+		assert.Len(t, str, 32)
+		keyMp[str] = true
 	}
+
+	assert.Len(t, keyMp, 10)
 }
 
 func TestRandomCharsV3(t *testing.T) {
-	for i := 0; i < 10; i++ {
+	size := 10
+	keyMp := make(map[string]bool)
+
+	for i := 0; i < size; i++ {
 		str := strutil.RandomCharsV3(4)
 		fmt.Println(str)
+		assert.Len(t, str, 4)
+		keyMp[str] = true
+	}
+	assert.Len(t, keyMp, size)
+}
 
+func TestRandWithTpl(t *testing.T) {
+	size := 10
+	keyMp := make(map[string]bool)
+
+	for i := 0; i < size; i++ {
+		str := strutil.RandWithTpl(4, strutil.AlphaBet1)
+		fmt.Println(str)
 		assert.Len(t, str, 4)
+		keyMp[str] = true
 	}
+	assert.Len(t, keyMp, size)
+
+	assert.NotEmpty(t, strutil.RandWithTpl(8, ""))
+	assert.NotEmpty(t, strutil.RandWithTpl(8, strutil.AlphaBet1))
 }
 
 func TestRandomBytes(t *testing.T) {
@@ -44,26 +78,22 @@ func TestRandomBytes(t *testing.T) {
 
 	// 1607400451937462000
 	tsn := time.Now().UnixNano()
-	rand.Seed(tsn)
+	rn := rand.New(rand.NewSource(tsn))
 
 	fmt.Println(tsn)
-	fmt.Println(rand.Intn(12))
-	fmt.Println(rand.Intn(12))
+	fmt.Println(rn.Intn(12), rn.Intn(12))
 
 	fmt.Println(string(b))
-	fmt.Println(base64.URLEncoding.EncodeToString(b))
-	fmt.Println(base64.StdEncoding.EncodeToString(b))
+	fmt.Println(strutil.B64Std.EncodeToString(b))
+	fmt.Println(strutil.B64URL.EncodeToString(b))
 	fmt.Println(hex.EncodeToString(b))
 	assert.NoErr(t, err)
 }
 
 func TestRandomString(t *testing.T) {
-	s, err := strutil.RandomString(3)
+	s, err := strutil.RandomString(16)
 
 	fmt.Println(s)
 	assert.NoErr(t, err)
 	assert.True(t, len(s) > 3)
-
-	assert.NotEmpty(t, strutil.RandWithTpl(8, ""))
-	assert.NotEmpty(t, strutil.RandWithTpl(8, strutil.AlphaBet))
 }