A plain JSON API over HTTPS. No client library required — every operation is one request, and the response is the same shape the SDK and MCP server return.
curl -X POST https://api.enlist.dev/v1/waitlists/$WAITLIST_ID/signups \ -H "Authorization: Bearer $ENLIST_API_KEY" \ -H "Content-Type: application/json" \ -d '{"email":"ada@example.com","utm_source":"launch-tweet"}'# { "id": "sgn_9f2…", "position": 47, "total": 1203 }A signup call returns { id, position, total } immediately — no second request to render "you're #47".
The API allows cross-origin requests, but the bearer key must never ship to the browser — proxy through your own server route.
REST, the SDK, and the MCP server all return identical fields, so switching between them later is not a rewrite.
REST, SDK, MCP, webhooks, and email — same key across all of them.