Open Collective vs Slack

Open Collective's GraphQL API (v2) queries collectives, expenses, transactions, and members for the platform's transparent nonprofit/open-source funding model, and public collective data is readable with no authentication at all. Its own docs flag the older REST API as still running but no longer developed, pointing new integrations at the GraphQL surface and a companion PDF service (for receipts and invoices) that accepts either a personal token or an OAuth bearer token. A personal access token, not a full OAuth app-review flow, is the documented way to authenticate for private or write access.

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.