4chan vs Slack

4chan's API serves the same read-only board and thread data every page renders — board lists, catalogs, threads, and posts — as plain JSON from the dedicated a.4cdn.org host, with no registration, key, or authentication of any kind required. Media referenced by posts is served from the sibling i.4cdn.org host, and the project's own GitHub repository (4chan/4chan-API) hosts the reference client and doubles as the canonical documentation, including the rule to cap requests at one per second. Cross-origin use from a browser is limited in practice: both the docs and a live probe confirm the API's CORS policy only allows requests originating from 4chan's own board pages, so a third-party site must proxy requests server-side rather than call it directly from client-side JavaScript.

Slack's Web API lets registered apps read and post messages, manage channels, and react to workspace events, authenticated with OAuth 2.0 bot or user tokens scoped to a single Slack workspace. Methods are rate-limited across four tiers and most write actions cap out around one request per second per workspace, so high-throughput integrations typically move to the Events API or Socket Mode instead of polling.