scodec/scodec-bits

Provides immutable datatypes for working with bits and bytes

softwaremill/magnolia

Easy, fast, transparent generic derivation of typeclass instances

twitter/finagle

A fault tolerant, protocol-agnostic RPC system

com-lihaoyi/sourcecode

Scala library providing "source" metadata to your program, similar to Python's __name__, C++'s __LINE__ or Ruby's __FILE__.

apache/kafka

Mirror of Apache Kafka

com-lihaoyi/scalatags

ScalaTags is a small XML/HTML construction library for Scala.

typelevel/spire

Powerful new number types and numeric abstractions for Scala.

circe/circe-generic-extras

Configurable generic derivation for Circe

typelevel/simulacrum

First class syntax support for type classes in Scala

com-lihaoyi/os-lib

OS-Lib is a simple, flexible, high-performance Scala interface to common OS filesystem and subprocess APIs

scala/scala-parallel-collections

Parallel collections standard library module for Scala 2.13+

alexarchambault/scalacheck-shapeless

Generation of arbitrary case classes / ADTs instances with scalacheck and shapeless

twitter/util

Wonderful reusable code from Twitter

scodec/scodec

Scala combinator library for working with binary data

playframework/scalatestplus-play

ScalaTest + Play

scalatest/scalatestplus-mockito

ScalaTest + JMock provides integration support between ScalaTest and Mockito.

tpolecat/doobie

Functional JDBC layer for Scala.

scalamacros/paradise

(No longer actively maintained.)

typelevel/discipline

Flexible law checking for Scala

typelevel/jawn

Jawn is for parsing jay-sawn (JSON)