I Built a Pay-Per-Call API Where the First Call Costs Nothing

A developer built Hermes Micro-Agent, a single HTTP endpoint that accepts USDC payments on the Base network and returns task results such as summarization, translation, code review and image description without requiring an account, API key or subscription. The service verifies each USDC transfer on-chain before running any work, returning HTTP 402 with the receiver address and price for unpaid requests, and offers four permanently free utility endpoints (hashing, base64, unit conversion, JSON minification) to break the discovery-versus-usage loop that hides paid-only endpoints. Prices range from $0.10 to $0.25 per task, with an OpenAPI spec, an x402 well-known document and a JSON-RPC interface for pricing and payment verification.

AI agents that need a task done should not need an account, an API key, or an invoice. They should be able to pay cents and get the result. That is what Hermes Micro-Agent does. It is a single HTTP endpoint that accepts USDC on Base and returns real work — no sign-up, no subscription, no human in the loop. Four services are free forever. Call them directly: SHA-256 hash of any text curl -X POST https://92.5.95.177.sslip.io/free/hash \ -H "Content-Type: application/json" -d '{"prompt":"hello world"}' Base64 encode/decode curl -X POST https://92.5.95.177.sslip.io/free/base64 \ -H "Content-Type: application/json" -d '{"prompt":"hello"}' Unit conversion length, weight, temperature, data size curl -X POST https://92.5.95.177.sslip.io/free/convert \ -H "Content-Type: application/json" -d '{"prompt":"10 km to miles"}' Minify a JSON document curl -X POST https://92.5.95.177.sslip.io/free/json minify \ -H "Content-Type: application/json" -d '{"prompt":"{ \"a\": 1 }"}' Each returns {"status":"success","task":"...","result":"...","free":true} . 1. See the price list curl https://92.5.95.177.sslip.io/tasks 2. Try a task — you get 402 with the address and the price curl -X POST https://92.5.95.177.sslip.io/task \ -H "Content-Type: application/json" \ -d '{"task":"summarize","prompt":"your text here"}' 3. Pay USDC on Base to the address in the 402, then retry with the tx hash curl -X POST https://92.5.95.177.sslip.io/task \ -H "Content-Type: application/json" \ -H "X-Payment: 0x<tx hash " \ -d '{"task":"summarize","prompt":"your text here"}' Or call a service by name — one route per task, so a search for the service finds the route: | Route | Service | Price | |---|---|---| | /summarize | Summarise text | $0.10 | | /extract | Extract key points | $0.10 | | /keywords | Find keywords | $0.10 | | /sentiment | Detect sentiment | $0.10 | | /translate | Translate | $0.15 | | /rewrite | Rewrite text | $0.15 | | /proofread | Proofread | $0.15 | | /code lint | Lint Python | $0.15 | | /code explain | Explain code | $0.15 | | /code refactor | Refactor code | $0.25 | | /code review | Review code | $0.25 | | /python debug | Debug Python | $0.25 | | /json query | Query JSON | $0.15 | | /csv to json | CSV to JSON | $0.15 | | /describe image | Describe an image | $0.15 | | /probe media | Probe a media URL | $0.15 | Receiver : 0x078fE079A9440631Bc6AD722D7143dC382b4ea4f Network : base eip155:8453 Asset : USDC 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 The USDC Transfer is verified on-chain before any work runs. Unpaid or unverifiable requests get 402 and nothing executes. https://92.5.95.177.sslip.io/openapi.json https://92.5.95.177.sslip.io/.well-known/x402 Price one task curl -X POST https://92.5.95.177.sslip.io/rpc \ -H "Content-Type: application/json" \ -d '{"jsonrpc":"2.0","id":1,"method":"price","params":{"task":"summarize"}}' Verify a payment curl -X POST https://92.5.95.177.sslip.io/rpc \ -H "Content-Type: application/json" \ -d '{"jsonrpc":"2.0","id":1,"method":"verify","params":{"tx hash":"0x...","min cents":1000}}' describe image and probe media fetch URLs — a failed fetch is reported as fetch failed: HTTP xxx , never invented. A paid-only endpoint is invisible: discovery directories rank by usage, and usage requires payment, and payment requires being discovered. The four free services break that loop — an agent can call them with no money and no account, which is what makes the paid services reachable in the first place. curl -X POST https://92.5.95.177.sslip.io/free/hash \ -H "Content-Type: application/json" -d '{"prompt":"hello world"}' If you are building an agent and want a deterministic, pay-per-call endpoint with no account and no subscription — this is it.