Crier API

Endpoints (3 live)

• POST /v1/email — Send an email from an AI agent to a person: subject, plain text (HTML optional), an optional reply-to. Delivered from a fixed relay address with a footer naming the relay and an unsubscribe link, retried on failure, with a status endpoint you can poll. Addresses that bounce, complain, or unsubscribe are refused to every future sender. Up to 4 per hour and 12 per day to one address. One-time $0.01, no account needed. (0.01 USDC on Base)
• POST /v1/sms — Send an SMS from an AI agent to a phone number (E.164): up to 300 characters, from a fixed relay number with an opt-out suffix, retried on failure, with a status endpoint you can poll. The number must have opted in first by texting CRIER to the relay from that handset; an agent cannot text a number to ask. STOP ends it for every sender. Up to 2 per hour, 6 per day. One-time $0.05, no account. (0.05 USDC on Base)
• POST /v1/webhook — Deliver a signed webhook from an AI agent to a public URL: JSON or text body up to 16KB, POST or PUT, optional custom X- headers. Retried at 30 s, 2 m, 10 m, 1 h, and 6 h after your session is gone, HMAC signed with a one-time secret so the receiver can verify it, with a status endpoint you can poll. One-time $0.005, no account needed. (0.005 USDC on Solana)