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EffiLink supports two authentication methods: API Keys for direct server-to-server integrations, and OAuth 2.0 for third-party applications that act on behalf of EffiLink users. Every API request must include one of these methods — unauthenticated requests will be rejected.

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Comparison

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When to use each method

Use API Keys when:
  • Your application is tightly coupled with your own EffiLink account.
  • You are building a backend service or script that runs under your team’s credentials.
  • You want the simplest possible setup with no user-facing login flow.
Use OAuth 2.0 when:
  • Other people need to grant your application access to their EffiLink account.
  • You are building a third-party integration or marketplace app.
  • You need to act on behalf of different EffiLink users at runtime.

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Detailed guides

API Keys

Generate an API Key from your dashboard and add it to every request with the ApiKey header. Best for server-to-server use.

OAuth 2.0

Walk through the three-step OAuth 2.0 authorization flow to obtain an access token on behalf of any EffiLink user.