Upwork vs USAJOBS

Upwork's public API is now a single GraphQL endpoint covering the freelance marketplace it once exposed as separate REST resources — job postings, proposals, contracts, time tracking, and messaging — authenticated via OAuth 2.0 (Authorization Code Grant with PKCE). A live probe confirmed the stored docs URL still redirects to the current GraphQL reference and that the gateway itself returns a genuine 401 challenge to unauthenticated calls, with no Access-Control-Allow-Origin header on either that request or a follow-up preflight. Registering an application is free, gated only by Upwork's own review and a 300-request-per-minute-per-IP rate limit.

USAJOBS is the official job board for the U.S. federal government, and its Search API returns current vacancy announcements plus dozens of reference code lists (agencies, pay plans, hiring paths). Every request needs a free registered email/API-key pair sent as custom headers, confirmed live by a genuine 401 challenge that also carried a wildcard CORS header.