Line's public APIs let you build your own front end on top of a Line inbox. Every API below is described by an OpenAPI 3.1 document and listed in a machine-readable catalog, so an agent can discover and call them without reading this page.

Start a visitor chat session from an authorised domain, send messages, and stream the assistant's replies.

Submit a hosted lead form. Line creates the contact, opens a conversation, and fires the form's workflow trigger.

Line publishes an API catalog at the well-known URI defined by RFC 9727. It is an RFC 9264 linkset listing each API with its OpenAPI description, its documentation, and a health endpoint.

Both APIs are addressed by a widget public key. Find yours in the Line dashboard under Settings → Webchat, and add the domains you will call from to the widget's allowed-domain list. Requests from any other origin are rejected.