This topic is meant to show a general way to call the Twitch API without OAuth. You can call any APIs found in the Twitch REST API documentation using this pattern. You would simply change the URL to the correct endpoint.
A Client-ID is required for all calls to the Twitch API. In these examples, the Client-ID is added as a header to each call. You can also add it with the client_id query string parameter. If you use an OAuth token, the Twitch API will automatically resolve the Client-ID for you.
You can register a developer application at the new client page on Twitch.
Twitch Chat is a simple IRC chat. For any serious development, there are multiple documents for it, including the most comprehensive and general ressource: http://ircdocs.horse/
IRC is a basic, plaintext based TCP protocol. Connecting to Twitch works just like any regular IRC service with a difference in authenticating:
Connection Initiation > Handshake > Usage
The handshake is regularly the hardest part to get right:
After building up the connection to the server, you are required to provide PASS and then a NICK, where PASS is an OAuth-Token (which you can generate here) and USER being the username to this OAuth token.
The handshake is then as following (< being sent from client to server, > being sent from server to client):
< PASS oauth:your_oauth_token
< NICK your_username
> :tmi.twitch.tv 001 your_username :connected to TMI
> :tmi.twitch.tv 002 your_username :your host is TMI
> :tmi.twitch.tv 003 your_username :this server is pretty new
> :tmi.twitch.tv 004 your_username tmi.twitch.tv 0.0.1 w n
> :tmi.twitch.tv 375 your_username :- tmi.twitch.tv Message of the day -
> :tmi.twitch.tv 372 your_username :- not much to say here
> :tmi.twitch.tv 376 your_username :End of /MOTD command
Once you received either any of these MODE, 376 or 422, you're good to go and can send the twitch server any commands, like:
> JOIN :#gamesdonequick
> PRIVMSG #gamesdonequick :Hello world!
A more throughout guide to client-server commands can be found here.
While Twitch uses a standard IRC service, there are some events seen on the IRC service which correlate to activity in a channel on the Twitch website. Examples here are slowmode being enabled or disabled, subscriber-only mode being enabled/disabled on a streamer's chat, hosting activity, and bits/cheer activity, among others.
Details on these Twitch-specific capabilities are listed in the GitHub documentation for Twitch IRC, which can be found here.