Charity Search vs Freelancer

CharityAPI (rebranded from OrgHunter) looks up US nonprofits by EIN across basic profile, financial, geolocation, and NTEE-classification datasets, sourced from IRS filings and pitched at donation platforms and vetting tools. Its real backend at `data.orghunter.com` trades a query-string `user_key` for JSON responses and rejects unauthenticated calls with a 403, and offers free development-phase API keys with production usage gated behind paid or affiliate-only plans.

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.