402cron — cron for AI agents, paid per delivery

402cron calls your https endpoint on a cron schedule, signs every request, and retries what fails. An agent can set it up on its own: no account, no card, no human in the loop. Payment is x402 — USDC on Base — and the only identity is the wallet that paid.

This repository holds documentation and runnable examples. The service runs at https://402cron.com; its source code is not published.

Links

• https://402cron.com — the service
• https://402cron.com/docs — machine-readable documentation (JSON; try ?section=quickstart)
• https://402cron.com/openapi.json — OpenAPI 3.1
• https://402cron.com/llms.txt — the service, explained for a model
• https://402cron.com/mcp — remote MCP server (streamable HTTP), listed in the official MCP Registry as com.402cron/402cron
• https://402cron.com/.well-known/agent-card.json — A2A agent card
• https://402cron.com/api/pricing — the tariff, machine-readable
• https://402cron.com/terms — terms · abuse@402cron.com

Further reading

• Nobody complains: 28 silent failures of a paid API for AI agents: x402 payment headers, agent catalogs, A2A cards and calling out from Cloudflare Workers, each with the cause, the fix and the check that catches it. Useful if you are building your own paid API for agents.

Pricing

The balance counts deliveries, not money, and never expires. Each delivery attempt uses one credit, so a failing delivery costs at most three. Current prices: https://402cron.com/api/pricing.

How it works

1. Buy. GET https://402cron.com/buy/trial answers 402 with the price in the PAYMENT-REQUIRED header. Pay with any x402 client. The receipt carries your management token, shown once.
2. Register. POST /api/destinations with {"url": "https://your.host/hook"} returns the destination id and its signing secret, shown once.
3. Verify. Call POST /api/destinations/{id}/verify. We POST a challenge to your URL and your endpoint echoes it back. The permission then covers that path and everything below it.
4. Schedule. POST /api/tasks with {"name", "url", "cron", "body"}. The response shows the next three runs.

Management calls take Authorization: Bearer <token>. Lost the token? Buy again from the same wallet with ?rotate=1; the old token stops working.

What your endpoint receives

Three kinds of requests arrive at the same URL. X-402cron-Event tells them apart:

The signature is X-402cron-Signature: sha256=<hex>, an HMAC-SHA256 keyed with your signing secret over the bytes of:

{X-402cron-Timestamp}\n{X-402cron-Delivery-Id}\n{X-402cron-Attempt}\n{METHOD}\n{path+query}\n{raw body}

The event label is not signed: branch on it, but trust what the signature covers. Delivery is at least once — the same X-402cron-Delivery-Id can arrive twice, so treat a repeat as already handled. Deliveries also carry X-402cron-Task-Id and X-402cron-Deliveries-Left.

Retries and pausing

• A timeout or an unreachable host is retried: up to 3 attempts, 60 s and 120 s apart.
• A 4xx or 5xx is your server's answer, so it is not retried.
• 3 failed attempts, 20 refusals in a row, or 10 server errors in a row pause the task. You get one task_paused notice; resuming is one call.

Limits

• cron: 5 fields, always UTC, one minute at the finest. Names (MON-FRI, JAN) and macros (@daily, @hourly, …) work; anything unsupported is refused with a code that says why.
• Destinations must be https://.
• Body up to 64 KB, custom headers up to 8 KB.

All limits: https://402cron.com/docs?section=limits

Examples

Both receivers answer the challenge, verify signatures, drop duplicate deliveries and log pause notices. The client reads the price from the PAYMENT-REQUIRED header like any standard x402 client, caps what it may spend (MAX_USD, default $0.05), and with DRY_RUN=1 signs without paying anything. On Windows PowerShell, set variables with $env:SECRET_402CRON="…" first.

Use it from an MCP client

Claude Code:

claude mcp add --transport http 402cron https://402cron.com/mcp --header "Authorization: Bearer <token>"

Other clients: add a remote (streamable HTTP) server at https://402cron.com/mcp with the same header. get_pricing, get_docs and get_service_status work without a token. There is no purchase tool on purpose: pay over plain HTTP, because a signed payment should not travel through a model's context.

Guarantee

We guarantee that we tried to deliver your task — not what someone else's server does with it. Full terms: https://402cron.com/terms

License

The examples in this repository are MIT-licensed — see LICENSE.