diff --git a/argonaut/src/main/scala/io/finch/argonaut/Decoders.scala b/argonaut/src/main/scala/io/finch/argonaut/Decoders.scala
index 511f039e8..4e23d7194 100644
--- a/argonaut/src/main/scala/io/finch/argonaut/Decoders.scala
+++ b/argonaut/src/main/scala/io/finch/argonaut/Decoders.scala
@@ -1,6 +1,7 @@
 package io.finch.argonaut
 
 import argonaut.{CursorHistory, DecodeJson, Json}
+import com.twitter.io.{Buf, Charsets}
 import com.twitter.util.{Return, Throw, Try}
 import io.finch._
 import io.finch.internal.BufText
@@ -16,12 +17,11 @@ trait Decoders {
   implicit def decodeArgonaut[A](implicit d: DecodeJson[A]): Decode.Json[A] =
     Decode.json { (b, cs) =>
       val err: (String, CursorHistory) => Try[A] = { (str, hist) => Throw[A](Error(str)) }
-
-      // TODO: Eliminate toString conversion
-      // See https://github.com/finagle/finch/issues/511
-      // Jawn can parse from ByteBuffer's if they represent UTF-8 strings.
-      // We can check the charset here and do parsing w/o extra to-string conversion.
-      Parser.parseFromString[Json](BufText.extract(b, cs))(facade) match {
+      val attemptJson = cs match {
+        case Charsets.Utf8 => Parser.parseFromByteBuffer[Json](Buf.ByteBuffer.Shared.extract(b))(facade)
+        case _ => Parser.parseFromString[Json](BufText.extract(b, cs))(facade)
+      }
+      attemptJson match {
         case Success(value) => d.decodeJson(value).fold[Try[A]](err, Return(_))
         case Failure(error) => Throw[A](Error(error.getMessage))
       }
diff --git a/circe/src/main/scala/io/finch/circe/Decoders.scala b/circe/src/main/scala/io/finch/circe/Decoders.scala
index d720f92de..d4c744e5a 100644
--- a/circe/src/main/scala/io/finch/circe/Decoders.scala
+++ b/circe/src/main/scala/io/finch/circe/Decoders.scala
@@ -1,9 +1,10 @@
 package io.finch.circe
 
 import cats.syntax.show._
+import com.twitter.io.{Buf, Charsets}
 import com.twitter.util.{Return, Throw, Try}
 import io.circe.Decoder
-import io.circe.jawn.decode
+import io.circe.jawn._
 import io.finch.{Decode, Error}
 import io.finch.internal.BufText
 
@@ -12,15 +13,11 @@ trait Decoders {
   /**
    * Maps a Circe's [[Decoder]] to Finch's [[Decode]].
    */
-  implicit def decodeCirce[A: Decoder]: Decode.Json[A] = Decode.json((b, cs) =>
-
-    // TODO: Eliminate toString conversion
-    // See https://github.com/finagle/finch/issues/511
-    // Jawn can parse from ByteBuffer's if they represent UTF-8 strings.
-    // We can check the charset here and do parsing w/o extra to-string conversion.
-    decode[A](BufText.extract(b, cs)).fold[Try[A]](
-      error => Throw[A](Error(error.show)),
-      value => Return(value)
-    )
-  )
+  implicit def decodeCirce[A: Decoder]: Decode.Json[A] = Decode.json({ (b, cs) =>
+    val attemptJson = cs match {
+      case Charsets.Utf8 => parseByteBuffer(Buf.ByteBuffer.Shared.extract(b)).right.flatMap(_.as[A])
+      case _ => decode[A](BufText.extract(b, cs))
+    }
+    attemptJson.fold[Try[A]](error => Throw[A](Error(error.show)), value => Return(value))
+  })
 }
diff --git a/jackson/src/main/scala/io/finch/jackson/package.scala b/jackson/src/main/scala/io/finch/jackson/package.scala
index bfb8b97a9..059f84a7e 100644
--- a/jackson/src/main/scala/io/finch/jackson/package.scala
+++ b/jackson/src/main/scala/io/finch/jackson/package.scala
@@ -1,20 +1,17 @@
 package io.finch
 
-import scala.reflect.ClassTag
-
 import com.fasterxml.jackson.databind.ObjectMapper
+import com.twitter.io.Buf
 import com.twitter.util.Try
 import io.finch.internal.BufText
+import scala.reflect.ClassTag
 
 package object jackson {
 
   implicit def decodeJackson[A](implicit
     mapper: ObjectMapper, ct: ClassTag[A]
   ): Decode.Json[A] = Decode.json((b, cs) =>
-    // TODO: Eliminate toString conversion
-    // See https://github.com/finagle/finch/issues/511
-    // Jackson can parse from byte[] automatically detecting the encoding.
-    Try(mapper.readValue(BufText.extract(b, cs), ct.runtimeClass.asInstanceOf[Class[A]]))
+    Try(mapper.readValue(Buf.ByteArray.Shared.extract(b), ct.runtimeClass.asInstanceOf[Class[A]]))
   )
 
   implicit def encodeJackson[A](implicit mapper: ObjectMapper): Encode.Json[A] =
diff --git a/playjson/src/main/scala/io/finch/playjson/package.scala b/playjson/src/main/scala/io/finch/playjson/package.scala
index 7ad906548..732d0d9ec 100644
--- a/playjson/src/main/scala/io/finch/playjson/package.scala
+++ b/playjson/src/main/scala/io/finch/playjson/package.scala
@@ -1,5 +1,6 @@
 package io.finch
 
+import com.twitter.io.Buf
 import com.twitter.util.Try
 import io.finch.internal.BufText
 import play.api.libs.json._
@@ -11,10 +12,7 @@ package object playjson {
    * @tparam A the type of the data to decode into
    */
   implicit def decodePlayJson[A](implicit reads: Reads[A]): Decode.Json[A] =
-    // TODO: Eliminate toString conversion
-    // See https://github.com/finagle/finch/issues/511
-    // PlayJson can parse from byte[] automatically detecting the charset.
-    Decode.json((b, cs) => Try(Json.parse(BufText.extract(b, cs)).as[A]))
+    Decode.json((b, cs) => Try(Json.parse(Buf.ByteArray.Shared.extract(b)).as[A]))
 
   /**
    * @param writes Play JSON `Writes` to use for encoding
diff --git a/sprayjson/src/main/scala/io/finch/sprayjson/package.scala b/sprayjson/src/main/scala/io/finch/sprayjson/package.scala
index de11a88a3..57db6efd0 100644
--- a/sprayjson/src/main/scala/io/finch/sprayjson/package.scala
+++ b/sprayjson/src/main/scala/io/finch/sprayjson/package.scala
@@ -1,5 +1,6 @@
 package io.finch
 
+import com.twitter.io.{Buf, Charsets}
 import com.twitter.util.Try
 import io.finch.internal.BufText
 import spray.json._
@@ -11,10 +12,12 @@ package object sprayjson{
     * @tparam A the type of the data to decode into
     */
   implicit def decodeSpray[A](implicit format: JsonFormat[A]): Decode.Json[A] =
-    // TODO: Eliminate toString conversion
-    // See https://github.com/finagle/finch/issues/511
-    // SprayJson can parse from byte[] if it represents a UTF-8 string.
-    Decode.json((b, cs) => Try(BufText.extract(b, cs).parseJson.convertTo[A]))
+    Decode.json({ (b, cs) =>
+      cs match {
+        case Charsets.Utf8 => Try(JsonParser(Buf.ByteArray.Shared.extract(b)).convertTo[A])
+        case _ => Try(BufText.extract(b, cs).parseJson.convertTo[A])
+      }
+    })
 
   /**
     * @param format spray-json support for convert JSON val to specific type object