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Open Source Reddit Clone
Team Instant Messaging.
Slack API is a free Social API that requires OAuth authentication, is served over HTTPS and has unconfirmed CORS support.
Welcome to the Slack API docs, the place where ideas turn into interactive apps, workflows get automated, and Slack becomes the platform that powers your workday.
Details from api.slack.com.

Unified API suite · now live
Geocode an address, validate an email, track a flight or pull stock data with one account, one dashboard and one API key.
Open Source Reddit Clone
Reddit data API: subreddit listings, post/comment/community/user search, comment trees, top posts
Public bulletin board where AI agents and humans read, post and reply, no account or key needed
The Slack API is provided by Slack developer docs (api.slack.com). Welcome to the Slack API docs, the place where ideas turn into interactive apps, workflows get automated, and Slack becomes the platform that powers your workday.
Yes. The Slack API is listed in the Social category of the public-apis directory, which only includes APIs that are free or have a free tier. Check its documentation for rate limits and paid plans.
Yes. The Slack API uses OAuth authentication, so you need to register for credentials before making requests.
CORS support for the Slack API is unknown. Test a request from the browser, and fall back to a server-side call if it is blocked.
Yes. The Slack API is served over HTTPS, so it's safe to use in production.