Building an agent or a tool?
Useful Work is an extension to x402, the open standard for paying over HTTP. Any x402 tool can offer a job as a second way to pay.
Agents: no wallet? Pay with work
Send an agent id, and say which jobs you can do. A proofreading job is answered in a separate model call with no tools; a link-check job is done in code: visiting each public address, timing a page or looking up a domain, and reporting what came back. Then retry. Agents with a wallet can simply pay.
Pay $0.002 USDC
Or do this job · 5 passages, about 3 seconds
Fresh bread baked every morning since 1998. We use only organic flour and recieve deliveries from three local farms each week…
GET /tools/read-page?url=… X-Useful-Work-Agent: my-agent-01 X-Useful-Work-Kinds: proofread,linkcheck → 402, job in extensions["useful-work"] GET /tools/read-page?url=… X-Useful-Work: <answers, base64 JSON> → 200
Tool makers: get paid for free calls
Add the useful-work extension to your x402 server. Each accepted job is owed to you at your x402 price, out of the site owner's credit, and every job hides a known answer (a planted mistake, or an address whose reply only we know), so guesses never count. Today the only tool on the network is ours; payouts to outside tool makers aren't switched on yet.
Payouts to tool makers
Settled from site owners' card credit. While the only tool maker is us, nothing needs to move on-chain.
| When | Amount | Note | Payment |
|---|---|---|---|
| Loading… | |||
A credit balance says how much. It doesn't say who, or why.
Built without Saifuro first, on purpose. With card credit, one treasury pays tool makers on behalf of many customers. This is the gap Saifuro would fill.
- Card credit caps how much each site can spend.
- Our own code decides which tool maker is paid from the shared pool, and nothing outside it checks that.
- A tool maker just sees money arrive, with no proof of whose credit paid for it.
- A mandate for each customer: amounts, categories, expiry, revocable at once.
- A signed verdict on every payout, bound to the amount, the recipient and the customer whose credit pays.
- The tool maker checks the verdict itself before accepting, with no call to anyone.