The API Rate Limit depends on the which type of token you use with your requests. If you make a request with just a client-id then you’re limited to 30/minute, if you use an App Access Token or a User Access Token then the rate limit is 800/minute.
Details can be found on the docs: https://dev.twitch.tv/docs/api/guide/#rate-limits
Some endpoints also have additional global rate limits, if these apply it will be mentioned in the reference section for that endpoint.
The deprecated v3 and v5 API don’t have a strict rate limit, but if you make excessive requests Twitch may take action, and the general guidance is to try not exceed 1 request a second.