diff --git a/commons-benchmark/jvm/src/main/scala/com/avsystem/commons/ser/GenCodecBenchmarks.scala b/commons-benchmark/jvm/src/main/scala/com/avsystem/commons/ser/GenCodecBenchmarks.scala
index e01f17402..b6067969f 100644
--- a/commons-benchmark/jvm/src/main/scala/com/avsystem/commons/ser/GenCodecBenchmarks.scala
+++ b/commons-benchmark/jvm/src/main/scala/com/avsystem/commons/ser/GenCodecBenchmarks.scala
@@ -39,5 +39,7 @@ object DummyInput extends Input {
   def readList() = ignored
   def readBoolean() = ignored
   def readDouble() = ignored
+  def readBigInt() = ignored
+  def readBigDecimal() = ignored
   def skip() = ()
 }
diff --git a/commons-benchmark/src/main/scala/com/avsystem/commons/ser/CirceJsonInputOutput.scala b/commons-benchmark/src/main/scala/com/avsystem/commons/ser/CirceJsonInputOutput.scala
index dc1617c9c..ca104edee 100644
--- a/commons-benchmark/src/main/scala/com/avsystem/commons/ser/CirceJsonInputOutput.scala
+++ b/commons-benchmark/src/main/scala/com/avsystem/commons/ser/CirceJsonInputOutput.scala
@@ -22,7 +22,9 @@ class CirceJsonOutput(consumer: Json => Any) extends Output {
   def writeInt(int: Int): Unit = consumer(Json.fromInt(int))
   def writeLong(long: Long): Unit = consumer(Json.fromLong(long))
   def writeDouble(double: Double): Unit = consumer(Json.fromDoubleOrString(double))
-  def writeBinary(binary: Array[Byte]): Unit = ???
+  def writeBigInt(bigInt: BigInt): Unit = consumer(Json.fromBigInt(bigInt))
+  def writeBigDecimal(bigDecimal: BigDecimal): Unit = consumer(Json.fromBigDecimal(bigDecimal))
+  def writeBinary(binary: Array[Byte]): Unit = consumer(Json.fromValues(binary.map(Json.fromInt(_))))
   def writeList(): ListOutput = new CirceJsonListOutput(consumer)
   def writeObject(): ObjectOutput = new CirceJsonObjectOutput(consumer)
   override def writeFloat(float: Float): Unit = consumer(Json.fromFloatOrString(float))
@@ -67,7 +69,10 @@ class CirceJsonInput(json: Json) extends Input {
   def readInt(): Int = asNumber.toInt.getOrElse(failNot("int"))
   def readLong(): Long = asNumber.toLong.getOrElse(failNot("long"))
   def readDouble(): Double = asNumber.toDouble
-  def readBinary(): Array[Byte] = ???
+  def readBigInt(): BigInt = asNumber.toBigInt.getOrElse(failNot("bigInteger"))
+  def readBigDecimal(): BigDecimal = asNumber.toBigDecimal.getOrElse(failNot("bigDecimal"))
+  def readBinary(): Array[Byte] = json.asArray.getOrElse(failNot("array")).iterator
+    .map(_.asNumber.flatMap(_.toByte).getOrElse(failNot("byte"))).toArray
   def readList(): ListInput = new CirceJsonListInput(json.asArray.getOrElse(failNot("array")))
   def readObject(): ObjectInput = new CirceJsonObjectInput(json.asObject.getOrElse(failNot("object")))
   def skip(): Unit = ()
diff --git a/commons-core/src/main/scala/com/avsystem/commons/serialization/GenCodec.scala b/commons-core/src/main/scala/com/avsystem/commons/serialization/GenCodec.scala
index d658b317b..8257ca0ab 100644
--- a/commons-core/src/main/scala/com/avsystem/commons/serialization/GenCodec.scala
+++ b/commons-core/src/main/scala/com/avsystem/commons/serialization/GenCodec.scala
@@ -287,8 +287,8 @@ object GenCodec extends RecursiveAutoCodecs with TupleGenCodecs {
   implicit lazy val LongCodec: GenCodec[Long] = create(_.readLong(), _ writeLong _)
   implicit lazy val FloatCodec: GenCodec[Float] = create(_.readFloat(), _ writeFloat _)
   implicit lazy val DoubleCodec: GenCodec[Double] = create(_.readDouble(), _ writeDouble _)
-  implicit lazy val BigIntCodec: GenCodec[BigInt] = createNullable(i => BigInt(i.readString()), (o, v) => o.writeString(v.toString))
-  implicit lazy val BigDecimalCodec: GenCodec[BigDecimal] = createNullable(i => BigDecimal(i.readString()), (o, v) => o.writeString(v.toString))
+  implicit lazy val BigIntCodec: GenCodec[BigInt] = createNullable(_.readBigInt(), _ writeBigInt _)
+  implicit lazy val BigDecimalCodec: GenCodec[BigDecimal] = createNullable(_.readBigDecimal(), _ writeBigDecimal _)
 
   implicit lazy val JBooleanCodec: GenCodec[JBoolean] = createNullable(_.readBoolean(), _ writeBoolean _)
   implicit lazy val JCharacterCodec: GenCodec[JCharacter] = createNullable(_.readChar(), _ writeChar _)
@@ -298,8 +298,10 @@ object GenCodec extends RecursiveAutoCodecs with TupleGenCodecs {
   implicit lazy val JLongCodec: GenCodec[JLong] = createNullable(_.readLong(), _ writeLong _)
   implicit lazy val JFloatCodec: GenCodec[JFloat] = createNullable(_.readFloat(), _ writeFloat _)
   implicit lazy val JDoubleCodec: GenCodec[JDouble] = createNullable(_.readDouble(), _ writeDouble _)
-  implicit lazy val JBigIntegerCodec: GenCodec[JBigInteger] = createNullable(i => new JBigInteger(i.readString()), (o, v) => o.writeString(v.toString))
-  implicit lazy val JBigDecimalCodec: GenCodec[JBigDecimal] = createNullable(i => new JBigDecimal(i.readString()), (o, v) => o.writeString(v.toString))
+  implicit lazy val JBigIntegerCodec: GenCodec[JBigInteger] =
+    createNullable(_.readBigInt().bigInteger, (o, v) => o.writeBigInt(BigInt(v)))
+  implicit lazy val JBigDecimalCodec: GenCodec[JBigDecimal] =
+    createNullable(_.readBigDecimal().bigDecimal, (o, v) => o.writeBigDecimal(BigDecimal(v)))
 
   implicit lazy val JDateCodec: GenCodec[JDate] = createNullable(i => new JDate(i.readTimestamp()), (o, d) => o.writeTimestamp(d.getTime))
   implicit lazy val StringCodec: GenCodec[String] = createNullable(_.readString(), _ writeString _)
diff --git a/commons-core/src/main/scala/com/avsystem/commons/serialization/InputOutput.scala b/commons-core/src/main/scala/com/avsystem/commons/serialization/InputOutput.scala
index 559da7085..5c1d83b1a 100644
--- a/commons-core/src/main/scala/com/avsystem/commons/serialization/InputOutput.scala
+++ b/commons-core/src/main/scala/com/avsystem/commons/serialization/InputOutput.scala
@@ -22,6 +22,8 @@ trait Output extends Any {
   def writeTimestamp(millis: Long): Unit = writeLong(millis)
   def writeFloat(float: Float): Unit = writeDouble(float)
   def writeDouble(double: Double): Unit
+  def writeBigInt(bigInt: BigInt): Unit
+  def writeBigDecimal(bigDecimal: BigDecimal): Unit
   def writeBinary(binary: Array[Byte]): Unit
   def writeList(): ListOutput
   def writeObject(): ObjectOutput
@@ -139,6 +141,8 @@ trait Input extends Any {
   def readTimestamp(): Long = readLong()
   def readFloat(): Float = readDouble().toFloat
   def readDouble(): Double
+  def readBigInt(): BigInt
+  def readBigDecimal(): BigDecimal
   def readBinary(): Array[Byte]
   def readList(): ListInput
   def readObject(): ObjectInput
diff --git a/commons-core/src/main/scala/com/avsystem/commons/serialization/SimpleValueInputOutput.scala b/commons-core/src/main/scala/com/avsystem/commons/serialization/SimpleValueInputOutput.scala
index ac7571160..3b0d48f84 100644
--- a/commons-core/src/main/scala/com/avsystem/commons/serialization/SimpleValueInputOutput.scala
+++ b/commons-core/src/main/scala/com/avsystem/commons/serialization/SimpleValueInputOutput.scala
@@ -28,6 +28,8 @@ object SimpleValueOutput {
   * - `Int`
   * - `Long`
   * - `Double`
+  * - `BigInt`
+  * - `BigDecimal`
   * - `Boolean`
   * - `String`
   * - `Array[Byte]`
@@ -49,27 +51,27 @@ class SimpleValueOutput(
   def this(consumer: Any => Unit) =
     this(consumer, new MHashMap[String, Any], new ListBuffer[Any])
 
-  def writeBinary(binary: Array[Byte]) = consumer(binary)
-  def writeString(str: String) = consumer(str)
-  def writeDouble(double: Double) = consumer(double)
-  def writeInt(int: Int) = consumer(int)
-
-  def writeList() = new ListOutput {
+  def writeNull(): Unit = consumer(null)
+  def writeBoolean(boolean: Boolean): Unit = consumer(boolean)
+  def writeString(str: String): Unit = consumer(str)
+  def writeInt(int: Int): Unit = consumer(int)
+  def writeLong(long: Long): Unit = consumer(long)
+  def writeDouble(double: Double): Unit = consumer(double)
+  def writeBigInt(bigInt: BigInt): Unit = consumer(bigInt)
+  def writeBigDecimal(bigDecimal: BigDecimal): Unit = consumer(bigDecimal)
+  def writeBinary(binary: Array[Byte]): Unit = consumer(binary)
+
+  def writeList(): ListOutput = new ListOutput {
     private val buffer = newListRepr
     def writeElement() = new SimpleValueOutput(buffer += _, newObjectRepr, newListRepr)
-    def finish() = consumer(buffer.result())
+    def finish(): Unit = consumer(buffer.result())
   }
 
-  def writeBoolean(boolean: Boolean) = consumer(boolean)
-
-  def writeObject() = new ObjectOutput {
+  def writeObject(): ObjectOutput = new ObjectOutput {
     private val result = newObjectRepr
     def writeField(key: String) = new SimpleValueOutput(v => result += ((key, v)), newObjectRepr, newListRepr)
-    def finish() = consumer(result)
+    def finish(): Unit = consumer(result)
   }
-
-  def writeLong(long: Long) = consumer(long)
-  def writeNull() = consumer(null)
 }
 
 object SimpleValueInput {
@@ -91,41 +93,42 @@ class SimpleValueInput(value: Any) extends Input {
     case _ => throw new ReadFailure(s"Expected ${classTag[B].runtimeClass} but got ${value.getClass}")
   }
 
-  def inputType = value match {
+  def inputType: InputType = value match {
     case null => InputType.Null
     case _: BSeq[Any] => InputType.List
     case _: BMap[_, Any] => InputType.Object
     case _ => InputType.Simple
   }
 
-  def readBinary() = doRead[Array[Byte]]
-  def readLong() = doReadUnboxed[Long, JLong]
-  def readNull() = if (value == null) null else throw new ReadFailure("not null")
-  def readObject() =
+  def readNull(): Null = if (value == null) null else throw new ReadFailure("not null")
+  def readBoolean(): Boolean = doReadUnboxed[Boolean, JBoolean]
+  def readString(): String = doRead[String]
+  def readInt(): Int = doReadUnboxed[Int, JInteger]
+  def readLong(): Long = doReadUnboxed[Long, JLong]
+  def readDouble(): Double = doReadUnboxed[Double, JDouble]
+  def readBigInt(): BigInt = doRead[JBigInteger]
+  def readBigDecimal(): BigDecimal = doRead[JBigDecimal]
+  def readBinary(): Array[Byte] = doRead[Array[Byte]]
+
+  def readObject(): ObjectInput =
     new ObjectInput {
       private val map = doRead[BMap[String, Any]]
       private val it = map.iterator.map {
         case (k, v) => new SimpleValueFieldInput(k, v)
       }
-      def nextField() = it.next()
-      override def peekField(name: String) = map.getOpt(name).map(new SimpleValueFieldInput(name, _))
-      def hasNext = it.hasNext
+      def nextField(): SimpleValueFieldInput = it.next()
+      override def peekField(name: String): Opt[SimpleValueFieldInput] = map.getOpt(name).map(new SimpleValueFieldInput(name, _))
+      def hasNext: Boolean = it.hasNext
     }
 
-  def readInt() = doReadUnboxed[Int, JInteger]
-  def readString() = doRead[String]
-
-  def readList() =
+  def readList(): ListInput =
     new ListInput {
       private val it = doRead[BSeq[Any]].iterator.map(new SimpleValueInput(_))
-      def nextElement() = it.next()
-      def hasNext = it.hasNext
+      def nextElement(): SimpleValueInput = it.next()
+      def hasNext: Boolean = it.hasNext
     }
 
-  def readBoolean() = doReadUnboxed[Boolean, JBoolean]
-  def readDouble() = doReadUnboxed[Double, JDouble]
-
-  def skip() = ()
+  def skip(): Unit = ()
 }
 
 class SimpleValueFieldInput(val fieldName: String, value: Any)
diff --git a/commons-core/src/main/scala/com/avsystem/commons/serialization/StreamInputOutput.scala b/commons-core/src/main/scala/com/avsystem/commons/serialization/StreamInputOutput.scala
index 7cab613f9..86a2f5519 100644
--- a/commons-core/src/main/scala/com/avsystem/commons/serialization/StreamInputOutput.scala
+++ b/commons-core/src/main/scala/com/avsystem/commons/serialization/StreamInputOutput.scala
@@ -29,6 +29,8 @@ private object FormatConstants {
   final val ObjectStartMarker: Byte = 11
   final val ListEndMarker: Byte = 12
   final val ObjectEndMarker: Byte = 13
+  final val BitIntMarker: Byte = 14
+  final val BigDecimalMarker: Byte = 15
 }
 
 import com.avsystem.commons.serialization.FormatConstants._
@@ -47,53 +49,68 @@ class StreamInput(is: DataInputStream) extends Input {
       InputType.Simple
   }
 
-  def readNull(): Null = if (markerByte == NullMarker)
-    null
-  else
-    throw new ReadFailure(s"Expected null, but $markerByte found")
-
-  def readString(): String = if (markerByte == StringMarker)
-    is.readUTF()
-  else
-    throw new ReadFailure(s"Expected string, but $markerByte found")
-
-  def readBoolean(): Boolean = if (markerByte == BooleanMarker)
-    is.readBoolean()
-  else
-    throw new ReadFailure(s"Expected boolean, but $markerByte found")
-
-  def readInt(): Int = if (markerByte == IntMarker)
-    is.readInt()
-  else
-    throw new ReadFailure(s"Expected int, but $markerByte found")
-
-  def readLong(): Long = if (markerByte == LongMarker)
-    is.readLong()
-  else
-    throw new ReadFailure(s"Expected long, but $markerByte found")
-
-  def readDouble(): Double = if (markerByte == DoubleMarker)
-    is.readDouble()
-  else
-    throw new ReadFailure(s"Expected double, but $markerByte found")
-
-  def readBinary(): Array[Byte] = if (markerByte == ByteArrayMarker) {
-    val binary = Array.ofDim[Byte](is.readInt())
-    is.readFully(binary)
-    binary
-  } else {
-    throw new ReadFailure(s"Expected binary array, but $markerByte found")
-  }
+  def readNull(): Null =
+    if (markerByte == NullMarker) null
+    else throw new ReadFailure(s"Expected null but $markerByte found")
+
+  def readString(): String =
+    if (markerByte == StringMarker) is.readUTF()
+    else throw new ReadFailure(s"Expected string but $markerByte found")
+
+  def readBoolean(): Boolean =
+    if (markerByte == BooleanMarker) is.readBoolean()
+    else throw new ReadFailure(s"Expected boolean but $markerByte found")
+
+  def readInt(): Int =
+    if (markerByte == IntMarker) is.readInt()
+    else throw new ReadFailure(s"Expected int but $markerByte found")
+
+  def readLong(): Long =
+    if (markerByte == LongMarker) is.readLong()
+    else throw new ReadFailure(s"Expected long but $markerByte found")
+
+  def readDouble(): Double =
+    if (markerByte == DoubleMarker) is.readDouble()
+    else throw new ReadFailure(s"Expected double but $markerByte found")
+
+  def readBigInt(): BigInt =
+    if (markerByte == BitIntMarker) {
+      val len = is.readInt()
+      val bytes = new Array[Byte](len)
+      is.read(bytes)
+      BigInt(bytes)
+    } else {
+      throw new ReadFailure(s"Expected big integer but $markerByte found")
+    }
 
-  def readList(): ListInput = if (markerByte == ListStartMarker)
-    new StreamListInput(is)
-  else
-    throw new ReadFailure(s"Expected list, but $markerByte found")
+  def readBigDecimal(): BigDecimal =
+    if (markerByte == BigDecimalMarker) {
+      val len = is.readInt()
+      val bytes = new Array[Byte](len)
+      is.read(bytes)
+      val unscaled = BigInt(bytes)
+      val scale = is.readInt()
+      BigDecimal(unscaled, scale)
+    } else {
+      throw new ReadFailure(s"Expected big decimal but $markerByte found")
+    }
 
-  def readObject(): ObjectInput = if (markerByte == ObjectStartMarker)
-    new StreamObjectInput(is)
-  else
-    throw new ReadFailure(s"Expected object, but $markerByte found")
+  def readBinary(): Array[Byte] =
+    if (markerByte == ByteArrayMarker) {
+      val binary = Array.ofDim[Byte](is.readInt())
+      is.readFully(binary)
+      binary
+    } else {
+      throw new ReadFailure(s"Expected binary array but $markerByte found")
+    }
+
+  def readList(): ListInput =
+    if (markerByte == ListStartMarker) new StreamListInput(is)
+    else throw new ReadFailure(s"Expected list but $markerByte found")
+
+  def readObject(): ObjectInput =
+    if (markerByte == ObjectStartMarker) new StreamObjectInput(is)
+    else throw new ReadFailure(s"Expected object but $markerByte found")
 
   def skip(): Unit = markerByte match {
     case NullMarker =>
@@ -121,6 +138,10 @@ class StreamInput(is: DataInputStream) extends Input {
       new StreamListInput(is).skipRemaining()
     case ObjectStartMarker =>
       new StreamObjectInput(is).skipRemaining()
+    case BitIntMarker =>
+      is.skipBytes(is.readInt())
+    case BigDecimalMarker =>
+      is.skipBytes(is.readInt() + Integer.BYTES)
     case unexpected =>
       throw new ReadFailure(s"Unexpected marker byte: $unexpected")
   }
@@ -182,14 +203,16 @@ private object StreamObjectInput {
   case class EmptyFieldInput(name: String) extends FieldInput {
     private def nope: Nothing = throw new ReadFailure(s"Something went horribly wrong ($name)")
 
-    def fieldName: String = nope
     def inputType: InputType = nope
+    def fieldName: String = nope
     def readNull(): Null = nope
     def readString(): String = nope
     def readBoolean(): Boolean = nope
     def readInt(): Int = nope
     def readLong(): Long = nope
     def readDouble(): Double = nope
+    def readBigInt(): BigInt = nope
+    def readBigDecimal(): BigDecimal = nope
     def readBinary(): Array[Byte] = nope
     def readList(): ListInput = nope
     def readObject(): ObjectInput = nope
@@ -232,6 +255,21 @@ class StreamOutput(os: DataOutputStream) extends Output {
     os.writeDouble(double)
   }
 
+  def writeBigInt(bigInt: BigInt): Unit = {
+    os.writeByte(BitIntMarker)
+    val bytes = bigInt.toByteArray
+    os.writeInt(bytes.length)
+    os.write(bytes)
+  }
+
+  def writeBigDecimal(bigDecimal: BigDecimal): Unit = {
+    os.writeByte(BigDecimalMarker)
+    val bytes = bigDecimal.bigDecimal.unscaledValue.toByteArray
+    os.writeInt(bytes.length)
+    os.write(bytes)
+    os.writeInt(bigDecimal.scale)
+  }
+
   def writeBinary(binary: Array[Byte]): Unit = {
     os.writeByte(ByteArrayMarker)
     os.writeInt(binary.length)
diff --git a/commons-core/src/main/scala/com/avsystem/commons/serialization/json/JsonStringInput.scala b/commons-core/src/main/scala/com/avsystem/commons/serialization/json/JsonStringInput.scala
index f065c0584..f6f813c6e 100644
--- a/commons-core/src/main/scala/com/avsystem/commons/serialization/json/JsonStringInput.scala
+++ b/commons-core/src/main/scala/com/avsystem/commons/serialization/json/JsonStringInput.scala
@@ -33,7 +33,8 @@ class JsonStringInput(reader: JsonReader, callback: AfterElement = AfterElementN
     case _ => afterElement()
   }
 
-  private def expectedError(tpe: JsonType) = throw new ReadFailure(s"Expected $tpe but got ${reader.jsonType}: ${reader.currentValue}")
+  private def expectedError(tpe: JsonType) =
+    throw new ReadFailure(s"Expected $tpe but got ${reader.jsonType}: ${reader.currentValue}")
 
   private def checkedValue[T](jsonType: JsonType): T = {
     if (reader.jsonType != jsonType) expectedError(jsonType)
@@ -64,6 +65,8 @@ class JsonStringInput(reader: JsonReader, callback: AfterElement = AfterElementN
   def readInt(): Int = matchNumericString(_.toInt)
   def readLong(): Long = matchNumericString(_.toLong)
   def readDouble(): Double = matchNumericString(_.toDouble)
+  def readBigInt(): BigInt = matchNumericString(BigInt(_))
+  def readBigDecimal(): BigDecimal = matchNumericString(BigDecimal(_))
   def readBinary(): Array[Byte] = {
     val hex = checkedValue[String](JsonType.string)
     val result = new Array[Byte](hex.length / 2)
@@ -213,7 +216,7 @@ final class JsonReader(val json: String) {
   private def readHex(): Int =
     fromHex(read())
 
-  private def parseNumber(): Any = {
+  private def parseNumber(): String = {
     val start = i
 
     if (isNext('-')) {
diff --git a/commons-core/src/main/scala/com/avsystem/commons/serialization/json/JsonStringOutput.scala b/commons-core/src/main/scala/com/avsystem/commons/serialization/json/JsonStringOutput.scala
index 4213c1a2c..32c2470eb 100644
--- a/commons-core/src/main/scala/com/avsystem/commons/serialization/json/JsonStringOutput.scala
+++ b/commons-core/src/main/scala/com/avsystem/commons/serialization/json/JsonStringOutput.scala
@@ -50,6 +50,8 @@ final class JsonStringOutput(builder: JStringBuilder) extends BaseJsonOutput wit
       writeString(double.toString)
     else builder.append(double.toString)
   }
+  def writeBigInt(bigInt: BigInt): Unit = builder.append(bigInt.toString)
+  def writeBigDecimal(bigDecimal: BigDecimal): Unit = builder.append(bigDecimal.toString)
   def writeBinary(binary: Array[Byte]): Unit = {
     builder.append('"')
     var i = 0
diff --git a/commons-core/src/test/scala/com/avsystem/commons/serialization/StreamInputOutputTest.scala b/commons-core/src/test/scala/com/avsystem/commons/serialization/StreamInputOutputTest.scala
index 63a8f4502..4432838f1 100644
--- a/commons-core/src/test/scala/com/avsystem/commons/serialization/StreamInputOutputTest.scala
+++ b/commons-core/src/test/scala/com/avsystem/commons/serialization/StreamInputOutputTest.scala
@@ -22,9 +22,11 @@ case class FieldTypes(
   i: Int,
   j: Long,
   k: Double,
-  l: Array[Byte],
-  m: Obj,
-  n: List[List[Obj]]
+  l: BigInt,
+  m: BigDecimal,
+  n: Array[Byte],
+  o: Obj,
+  p: List[List[Obj]]
 )
 
 class StreamInputOutputTest extends FunSuite {
@@ -42,6 +44,8 @@ class StreamInputOutputTest extends FunSuite {
     -5,
     -6,
     -7.3,
+    BigInt("5345224654563123434325343"),
+    BigDecimal(BigInt("2356342454564522135435"), 150),
     Array[Byte](1, 2, 4, 2),
     Obj(10, "x"),
     List(
@@ -90,8 +94,8 @@ class StreamInputOutputTest extends FunSuite {
 
   test("encode and decode all field types in a complicated structure") {
     val encoded = encDec(fieldTypesInstance)
-    assert(fieldTypesInstance.l sameElements encoded.l)
-    assert(fieldTypesInstance == encoded.copy(l = fieldTypesInstance.l))
+    assert(fieldTypesInstance.n sameElements encoded.n)
+    assert(fieldTypesInstance == encoded.copy(n = fieldTypesInstance.n))
   }
 
   test("raw API usage") {
diff --git a/commons-core/src/test/scala/com/avsystem/commons/serialization/json/JsonStringInputOutputTest.scala b/commons-core/src/test/scala/com/avsystem/commons/serialization/json/JsonStringInputOutputTest.scala
index de1f499bf..fca6b1ff2 100644
--- a/commons-core/src/test/scala/com/avsystem/commons/serialization/json/JsonStringInputOutputTest.scala
+++ b/commons-core/src/test/scala/com/avsystem/commons/serialization/json/JsonStringInputOutputTest.scala
@@ -199,6 +199,8 @@ class JsonStringInputOutputTest extends FunSuite with SerializationTestUtils wit
       deserialized.i2.long shouldBe item.i2.long
       deserialized.i2.float shouldBe item.i2.float
       deserialized.i2.double shouldBe item.i2.double
+      deserialized.i2.bigInt shouldBe item.i2.bigInt
+      deserialized.i2.bigDecimal shouldBe item.i2.bigDecimal
       deserialized.i2.binary shouldBe item.i2.binary
       deserialized.i2.list shouldBe item.i2.list
       deserialized.i2.set shouldBe item.i2.set
@@ -207,7 +209,6 @@ class JsonStringInputOutputTest extends FunSuite with SerializationTestUtils wit
     }
   }
 
-
   test("serialize and deserialize huge case classes") {
     implicit val arbTree: Arbitrary[DeepNestedTestCC] =
       Arbitrary {
diff --git a/commons-core/src/test/scala/com/avsystem/commons/serialization/json/SerializationTestUtils.scala b/commons-core/src/test/scala/com/avsystem/commons/serialization/json/SerializationTestUtils.scala
index 9ba346748..00a65f2f8 100644
--- a/commons-core/src/test/scala/com/avsystem/commons/serialization/json/SerializationTestUtils.scala
+++ b/commons-core/src/test/scala/com/avsystem/commons/serialization/json/SerializationTestUtils.scala
@@ -26,8 +26,8 @@ trait SerializationTestUtils {
   case class CompleteItem(
     unit: Unit, string: String, char: Char,
     boolean: Boolean, byte: Byte, short: Short, int: Int,
-    long: Long, float: Float, double: Double, binary: Array[Byte], list: List[String],
-    set: Set[String], obj: TestCC, map: Map[String, Int]
+    long: Long, float: Float, double: Double, bigInt: BigInt, bigDecimal: BigDecimal,
+    binary: Array[Byte], list: List[String], set: Set[String], obj: TestCC, map: Map[String, Int]
   )
   object CompleteItem extends HasGenCodec[CompleteItem] {
     implicit val arb: Arbitrary[CompleteItem] = Arbitrary(for {
@@ -41,11 +41,13 @@ trait SerializationTestUtils {
       l <- arbitrary[Long]
       f <- arbitrary[Float]
       d <- arbitrary[Double]
+      bi <- arbitrary[BigInt]
+      bd <- arbitrary[BigDecimal]
       binary <- arbitrary[Array[Byte]]
       list <- arbitrary[List[String]]
       set <- arbitrary[Set[String]]
       obj <- arbitrary[TestCC]
       map <- arbitrary[Map[String, Int]]
-    } yield CompleteItem(u, str, c, bool, b, s, i, l, f, d, binary, list, set, obj, map))
+    } yield CompleteItem(u, str, c, bool, b, s, i, l, f, d, bi, bd, binary, list, set, obj, map))
   }
 }
diff --git a/commons-mongo/src/main/scala/com/avsystem/commons/mongo/BsonInputOutput.scala b/commons-mongo/src/main/scala/com/avsystem/commons/mongo/BsonInputOutput.scala
index dd8f34e8e..ed9c41768 100644
--- a/commons-mongo/src/main/scala/com/avsystem/commons/mongo/BsonInputOutput.scala
+++ b/commons-mongo/src/main/scala/com/avsystem/commons/mongo/BsonInputOutput.scala
@@ -1,6 +1,8 @@
 package com.avsystem.commons
 package mongo
 
+import java.nio.ByteBuffer
+
 import com.avsystem.commons.serialization.{Input, Output}
 import org.bson.types.ObjectId
 
@@ -8,6 +10,24 @@ trait BsonInput extends Any with Input {
   def readObjectId(): ObjectId
 }
 
+object BsonInput {
+  def bigDecimalFromBytes(bytes: Array[Byte]): BigDecimal = {
+    val buf = ByteBuffer.wrap(bytes)
+    val unscaledBytes = new Array[Byte](bytes.length - Integer.BYTES)
+    buf.get(unscaledBytes)
+    val unscaled = BigInt(unscaledBytes)
+    val scale = buf.getInt
+    BigDecimal(unscaled, scale)
+  }
+}
+
 trait BsonOutput extends Any with Output {
   def writeObjectId(objectId: ObjectId): Unit
 }
+
+object BsonOutput {
+  def bigDecimalBytes(bigDecimal: BigDecimal): Array[Byte] = {
+    val unscaledBytes = bigDecimal.bigDecimal.unscaledValue.toByteArray
+    ByteBuffer.allocate(unscaledBytes.length + Integer.BYTES).put(unscaledBytes).putInt(bigDecimal.scale).array
+  }
+}
diff --git a/commons-mongo/src/main/scala/com/avsystem/commons/mongo/BsonReaderInput.scala b/commons-mongo/src/main/scala/com/avsystem/commons/mongo/BsonReaderInput.scala
index 4c36887e6..77b256014 100644
--- a/commons-mongo/src/main/scala/com/avsystem/commons/mongo/BsonReaderInput.scala
+++ b/commons-mongo/src/main/scala/com/avsystem/commons/mongo/BsonReaderInput.scala
@@ -24,6 +24,8 @@ class BsonReaderInput(br: BsonReader) extends BsonInput {
   override def readLong(): Long = br.readInt64()
   override def readTimestamp(): Long = br.readDateTime()
   override def readDouble(): Double = br.readDouble()
+  override def readBigInt(): BigInt = BigInt(br.readBinaryData().getData)
+  override def readBigDecimal(): BigDecimal = BsonInput.bigDecimalFromBytes(br.readBinaryData().getData)
   override def readBinary(): Array[Byte] = br.readBinaryData().getData
   override def readList(): BsonReaderListInput = {
     br.readStartArray()
diff --git a/commons-mongo/src/main/scala/com/avsystem/commons/mongo/BsonValueOutput.scala b/commons-mongo/src/main/scala/com/avsystem/commons/mongo/BsonValueOutput.scala
index c3ed12341..c9f59531f 100644
--- a/commons-mongo/src/main/scala/com/avsystem/commons/mongo/BsonValueOutput.scala
+++ b/commons-mongo/src/main/scala/com/avsystem/commons/mongo/BsonValueOutput.scala
@@ -33,6 +33,8 @@ final class BsonValueOutput(receiver: BsonValue => Unit = _ => ()) extends BsonO
   override def writeLong(long: Long): Unit = setValue(new BsonInt64(long))
   override def writeTimestamp(millis: Long): Unit = setValue(new BsonDateTime(millis))
   override def writeDouble(double: Double): Unit = setValue(new BsonDouble(double))
+  override def writeBigInt(bigInt: BigInt): Unit = setValue(new BsonBinary(bigInt.toByteArray))
+  override def writeBigDecimal(bigDecimal: BigDecimal): Unit = setValue(new BsonBinary(BsonOutput.bigDecimalBytes(bigDecimal)))
   override def writeBinary(binary: Array[Byte]): Unit = setValue(new BsonBinary(binary))
   override def writeList(): ListOutput = new BsonValueListOutput(setValue)
   override def writeObject(): ObjectOutput = new BsonValueObjectOutput(setValue)
diff --git a/commons-mongo/src/main/scala/com/avsystem/commons/mongo/BsonWriterOutput.scala b/commons-mongo/src/main/scala/com/avsystem/commons/mongo/BsonWriterOutput.scala
index 12e373d57..5490c9e05 100644
--- a/commons-mongo/src/main/scala/com/avsystem/commons/mongo/BsonWriterOutput.scala
+++ b/commons-mongo/src/main/scala/com/avsystem/commons/mongo/BsonWriterOutput.scala
@@ -13,6 +13,10 @@ final class BsonWriterOutput(bw: BsonWriter) extends BsonOutput {
   override def writeLong(long: Long): Unit = bw.writeInt64(long)
   override def writeTimestamp(millis: Long): Unit = bw.writeDateTime(millis)
   override def writeDouble(double: Double): Unit = bw.writeDouble(double)
+  override def writeBigInt(bigInt: BigInt): Unit =
+    bw.writeBinaryData(new BsonBinary(bigInt.toByteArray))
+  override def writeBigDecimal(bigDecimal: BigDecimal): Unit =
+    bw.writeBinaryData(new BsonBinary(BsonOutput.bigDecimalBytes(bigDecimal)))
   override def writeBinary(binary: Array[Byte]): Unit = bw.writeBinaryData(new BsonBinary(binary))
   override def writeList(): BsonWriterListOutput = {
     bw.writeStartArray()
@@ -33,6 +37,10 @@ final class BsonWriterNamedOutput(escapedName: String, bw: BsonWriter) extends B
   override def writeLong(long: Long): Unit = bw.writeInt64(escapedName, long)
   override def writeTimestamp(millis: Long): Unit = bw.writeDateTime(escapedName, millis)
   override def writeDouble(double: Double): Unit = bw.writeDouble(escapedName, double)
+  override def writeBigInt(bigInt: BigInt): Unit =
+    bw.writeBinaryData(escapedName, new BsonBinary(bigInt.toByteArray))
+  override def writeBigDecimal(bigDecimal: BigDecimal): Unit =
+    bw.writeBinaryData(escapedName, new BsonBinary(BsonOutput.bigDecimalBytes(bigDecimal)))
   override def writeBinary(binary: Array[Byte]): Unit = bw.writeBinaryData(escapedName, new BsonBinary(binary))
   override def writeList(): BsonWriterListOutput = {
     bw.writeStartArray(escapedName)
diff --git a/commons-mongo/src/test/scala/com/avsystem/commons/mongo/BigDecimalEncodingTest.scala b/commons-mongo/src/test/scala/com/avsystem/commons/mongo/BigDecimalEncodingTest.scala
new file mode 100644
index 000000000..a77014a1e
--- /dev/null
+++ b/commons-mongo/src/test/scala/com/avsystem/commons/mongo/BigDecimalEncodingTest.scala
@@ -0,0 +1,13 @@
+package com.avsystem.commons
+package mongo
+
+import org.scalatest.FunSuite
+import org.scalatest.prop.PropertyChecks
+
+class BigDecimalEncodingTest extends FunSuite with PropertyChecks {
+  test("BigDecimal BSON encoding") {
+    forAll { value: BigDecimal =>
+      assert(value == BsonInput.bigDecimalFromBytes(BsonOutput.bigDecimalBytes(value)))
+    }
+  }
+}