API key authentication
Problem: Connect to an API that uses API key in the Authorization header. Solution:uhttp package handles retries and rate limiting automatically. WithBearerToken sets Authorization: Bearer <token>.
OAuth2 client credentials
Problem: Exchange client ID and secret for an access token. Solution:clientcredentials package handles token refresh automatically. You don’t need to manage token expiry.
JWT service account (Google-style)
Problem: Authenticate with a service account JSON key file. Solution:Subject field specifies which user to impersonate.