Choose the provider-specific guide
Each provider has its own endpoint, response format, and access requirements. CORSPROXY returns the provider response; it does not normalize prices into a common finance API.
Separate CORS from an upstream denial
If the provider already allows your browser origin, direct access may be sufficient. If it returns 401, 403, 429, or a region-restriction response, resolve that upstream issue before treating it as CORS. A proxy subscription does not grant provider access.
Choose freshness for your widget
A slowly updated watchlist and a live chart need different freshness windows. Production caching controls can reduce repeated upstream reads, but cached data can be stale. Display timestamps and choose the cache lifetime for your actual application.
Keep authenticated trading separate
The provider guides here focus on public, read-only market data. Keep private account and trading credentials on your backend. Use the provider’s supported authentication and error handling for those operations.