diff --git a/CHANGELOG.md b/CHANGELOG.md
index b421cb4c..033341d9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,8 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
 ## [Unreleased]
+### Changed
+- Add a correct content type to POST requests and SearchFilters adjustments [#359](https://github.com/azavea/stac4s/pull/359)
 
 ## [0.6.0] - 2021-07-01
 ### Added
diff --git a/modules/client/js/src/main/scala/com/azavea/stac4s/api/client/SearchFilters.scala b/modules/client/js/src/main/scala/com/azavea/stac4s/api/client/SearchFilters.scala
index 0fde0605..7375aa8a 100644
--- a/modules/client/js/src/main/scala/com/azavea/stac4s/api/client/SearchFilters.scala
+++ b/modules/client/js/src/main/scala/com/azavea/stac4s/api/client/SearchFilters.scala
@@ -4,6 +4,7 @@ import com.azavea.stac4s.api.client.util.ClientCodecs
 import com.azavea.stac4s.geometry.Geometry
 import com.azavea.stac4s.{Bbox, TemporalExtent}
 
+import cats.syntax.option._
 import eu.timepit.refined.types.numeric.NonNegInt
 import io.circe._
 import io.circe.refined._
@@ -39,8 +40,8 @@ object SearchFilters extends ClientCodecs {
         bbox,
         datetime,
         intersects,
-        collectionsOption.getOrElse(Nil),
-        itemsOption.getOrElse(Nil),
+        collectionsOption getOrElse Nil,
+        itemsOption getOrElse Nil,
         limit,
         query getOrElse Map.empty,
         paginationToken
@@ -62,10 +63,10 @@ object SearchFilters extends ClientCodecs {
       filters.bbox,
       filters.datetime,
       filters.intersects,
-      filters.collections,
-      filters.items,
+      filters.collections.some.filter(_.nonEmpty),
+      filters.items.some.filter(_.nonEmpty),
       filters.limit,
-      filters.query,
+      filters.query.some.filter(_.nonEmpty),
       filters.next
     )
   )
diff --git a/modules/client/jvm/src/main/scala/com/azavea/stac4s/api/client/SearchFilters.scala b/modules/client/jvm/src/main/scala/com/azavea/stac4s/api/client/SearchFilters.scala
index f64088d6..ce65366d 100644
--- a/modules/client/jvm/src/main/scala/com/azavea/stac4s/api/client/SearchFilters.scala
+++ b/modules/client/jvm/src/main/scala/com/azavea/stac4s/api/client/SearchFilters.scala
@@ -3,6 +3,7 @@ package com.azavea.stac4s.api.client
 import com.azavea.stac4s.api.client.util.ClientCodecs
 import com.azavea.stac4s.{Bbox, TemporalExtent}
 
+import cats.syntax.option._
 import eu.timepit.refined.types.numeric.NonNegInt
 import geotrellis.vector.{io => _, _}
 import io.circe._
@@ -39,8 +40,8 @@ object SearchFilters extends ClientCodecs {
         bbox,
         datetime,
         intersects,
-        collectionsOption.getOrElse(Nil),
-        itemsOption.getOrElse(Nil),
+        collectionsOption getOrElse Nil,
+        itemsOption getOrElse Nil,
         limit,
         query getOrElse Map.empty,
         paginationToken
@@ -62,10 +63,10 @@ object SearchFilters extends ClientCodecs {
       filters.bbox,
       filters.datetime,
       filters.intersects,
-      filters.collections,
-      filters.items,
+      filters.collections.some.filter(_.nonEmpty),
+      filters.items.some.filter(_.nonEmpty),
       filters.limit,
-      filters.query,
+      filters.query.some.filter(_.nonEmpty),
       filters.next
     )
   )
diff --git a/modules/client/shared/src/main/scala/com/azavea/stac4s/api/client/SttpStacClientF.scala b/modules/client/shared/src/main/scala/com/azavea/stac4s/api/client/SttpStacClientF.scala
index c64feac9..8234fd63 100644
--- a/modules/client/shared/src/main/scala/com/azavea/stac4s/api/client/SttpStacClientF.scala
+++ b/modules/client/shared/src/main/scala/com/azavea/stac4s/api/client/SttpStacClientF.scala
@@ -17,7 +17,7 @@ import io.circe.{Encoder, Json, JsonObject}
 import monocle.Lens
 import sttp.client3.circe.asJson
 import sttp.client3.{Response, SttpBackend, UriContext, basicRequest}
-import sttp.model.Uri
+import sttp.model.{MediaType, Uri}
 
 case class SttpStacClientF[F[_]: MonadThrow, S: Lens[*, Option[PaginationToken]]: Encoder](
     client: SttpBackend[F, Any],
@@ -40,7 +40,13 @@ case class SttpStacClientF[F[_]: MonadThrow, S: Lens[*, Option[PaginationToken]]
     Stream
       .unfoldLoopEval((baseUri.addPath("search"), initialBody)) { case (link, request) =>
         client
-          .send(basicRequest.body(request.noSpaces).post(link).response(asJson[Json]))
+          .send(
+            basicRequest
+              .post(link)
+              .contentType(MediaType.ApplicationJson)
+              .body(request.deepDropNullValues.noSpaces)
+              .response(asJson[Json])
+          )
           .flatMap { response =>
             val items = response.stacItems
             val next  = response.nextLink.nested.map(_ -> noPaginationBody).value
@@ -77,6 +83,7 @@ case class SttpStacClientF[F[_]: MonadThrow, S: Lens[*, Option[PaginationToken]]
       .send(
         basicRequest
           .post(baseUri.addPath("collections"))
+          .contentType(MediaType.ApplicationJson)
           .body(collection.asJson.noSpaces)
           .response(asJson[StacCollection])
       )
@@ -109,6 +116,7 @@ case class SttpStacClientF[F[_]: MonadThrow, S: Lens[*, Option[PaginationToken]]
       .send(
         basicRequest
           .post(baseUri.addPath("collections", collectionId.value, "items"))
+          .contentType(MediaType.ApplicationJson)
           .body(item.asJson.noSpaces)
           .response(asJson[StacItem])
       )