Libraries:

discordcr

A minimalist Crystal library for Discord, focused on performance and control rather than ease-of-use.

discord.io

A Javascript library for Discord.

eris

A NodeJS library for Discord.

RestCord

A PHP REST library for Discord.

Discordia

Discord API library written in Lua for the Luvit environment

nyx

A Dart library for Discord.

serenity

An Rust library for the Discord API.

discordie

A Node.js module providing a set of interfaces to interact with Discord API.

DiscordPHP

A PHP REST and WebSocket library for Discord.

Sword

A Discord Library for Swift

DiscordUnity

A library for Discord within unity.

Discordgo

Go bindings for Discord.

litcord

Yet another unofficial Lua client API for Discord.

discord.js

A Javascript library for Discord.

discord-hs

A Haskell library for Discord.

discordrb

A Ruby library for Discord.

Discord.Net

A C# library for Discord.

Discord4J

A Java binding for the Discord API.

JDA

A Java wrapper for the Discord REST and Websocket API.

Javacord

A multithreaded but simple to use discord java api.

discord-rs

A Rust library for the Discord API.

DSharpPlus

A C# API for Discord based off DiscordSharp, but rewritten to fit the API standards

discord.py

A Python library for Discord.