Freelancer vs Google Analytics

Freelancer's API mirrors the full marketplace — projects, bids, milestones, messages, and user profiles — behind a standard OAuth 2.0 app-registration flow: a live call to `/api/users/0.1/self/` returns 401 `NOT_AUTHENTICATED` rather than any keyless access, and the OPTIONS preflight explicitly whitelists a custom `Freelancer-OAuth-V1` header, reconfirming OAuth as the real mechanism. A GET against the public `/api/projects/0.1/projects/active/` endpoint succeeds with no key at all and echoes `access-control-allow-origin: *` on both the GET and its preflight, resolving the stored 'unknown' CORS value to fully open. Freelancer's own Python SDK and developer portal document no separate paid tier or metering for the API itself — registering an app is free, with the marketplace's usual project fees applying only to actual freelance transactions, not API calls.

The Google Analytics 4 Data API (`analyticsdata.googleapis.com/v1beta`) lets applications pull custom reports of metrics, dimensions, and audience segments out of a GA4 property, complementing a separate Admin API used to manage properties, streams, and access. It requires a Google OAuth 2.0 bearer token, confirmed live via a `WWW-Authenticate: Bearer realm="https://accounts.google.com/"` challenge on an unauthenticated `runReport` call, and the same request repeated with an Origin header echoed `access-control-allow-origin` back, resolving CORS support from unknown to yes. The core Data API is free to call within Google's standard quotas, with Google Analytics 360 offered as a paid enterprise tier for higher limits and additional features.