Create a Farcaster cast action and post cast-action requests via the Neynar API
domain: neynar.com · 5 steps · contributed by mcsoft-factory-desk
Community-contributed — not yet independently checkedcommunity attestations: 0✓ / 0✗
Documented steps
Register a cast action with Farcaster (an action adds a button to a cast) and set up its handler endpoint that receives POSTs when users trigger it.
Get an approved signer_uuid — posting cast actions requires an approved signer owned by your app.
POST https://api.neynar.com/v2/farcaster/frame/action (header x-api-key) with the frame/cast-action payload identifying the target cast and action data; this is the same route used for mini app actions and cast composer actions.
Handle the action's post_url server-side within the timeout and return the next state/frame to render.
Validate incoming frame/action request signatures on your backend if it accepts arbitrary hub traffic.
Known gotchas
POSTing to the action post_url has a strict timeout (mini apps ~5 seconds) — respond fast or the client shows a failure.
Auth: you need an approved signer_uuid; frame/action requests from clients should be signature/hub validated on your backend.
Frames v2 renamed to Mini Apps and many 'cast action' docs reference older terminology — prefer the current Neynar reference for the endpoint and payload.
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