Skip to main content
Every Link API request — admin and runtime — must carry a bearer JSON Web Token (JWT) in the Authorization header:
Authorization: Bearer <access_token>

Obtaining a token

Link runs on Hellgate-managed infrastructure and authenticates with the platform OAuth2 flow. Exchange your client credentials for an access token, then send it as a bearer token. Your instance’s audience is its instance name — the {instance} slug from your base URL — and you request it together with the scopes your client needs:
audience=my-link-instance
When Link is invoked transitively by another service — for example Specter composing with Link — the token must name every instance in the composition and carry the union of their scopes (for example, audience=my-specter-instance my-link-instance). See Composition for details. See Platform Authentication for the token endpoint, audiences, and the client-credentials request.

Scopes

Each endpoint requires a specific scope. Issue every token with the least privilege it needs — runtime clients should hold only invoke:execute, while configuration and operations belong to separate admin clients.
ScopeGrants
invoke:executeInvoke protocol actions (/api/invoke/{protocol}/{action})
admin:protocols:readRead protocols, requirements, and generated specs
admin:protocols:writeCreate, import, and delete protocols
admin:backends:readRead backends
admin:backends:writeCreate, update, delete, and rotate credentials on backends
admin:managed-backends:writeManage Hellgate-operated (managed) backends and their secrets
admin:keys:readRead message-level-encryption keys
admin:keys:writeCreate, update, delete, and rotate encryption keys
admin:executions:readRead execution audit logs
Runtime and admin scopes serve different audiences. Grant invoke:execute to your payment or decisioning integration; reserve the admin:* scopes for operator and back-office clients that configure protocols, backends, and keys.

Next steps

Quickstart

Use your token to import a protocol, register a backend, and invoke an action.