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Selo is a release gate for paid x402 APIs on Algorand. Before you ship, Selo becomes your customer: it pays your endpoint for real on Algorand Mainnet, checks what comes back against the contract you declare, and lets the release out only on a proven, signed PASS.

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Why a paid endpoint needs its own gate

A paid endpoint can pass every health check and still break for the people who pay for it. The payment settles, the server answers 200, and the response is missing a field every buyer depends on. Uptime checks, unit tests and integration tests never pay, so they never see what a paying customer sees. Selo tests the one path they skip: the paid request itself.

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What a release test does

1

You authorize your endpoint

You prove you own the route by serving a one-line token from your own domain. Selo never tests a route that is not authorized.
2

You pay Selo over x402

One command pays Selo 1.00 USDC through a standard x402 payment. Nothing else happens until that payment has settled on chain.
3

Selo pays your endpoint as a real client

Selo reads your 402, pays your price from its own wallet, and replays the identical signed payment to test retry safety. Spend is capped per job.
4

Five checks, one verdict

Selo runs five release checks and reduces them to a deterministic PASS, FAIL or INCONCLUSIVE. Unknown is never PASS.
5

The gate decides

The selo CLI exits 0 only on a fully evidenced PASS. Your terminal or GitHub Actions blocks the release on anything else. Every verdict is Ed25519-signed, so anyone can verify it offline.

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Proven on Algorand Mainnet

On 26 October 2026 a demo merchant at https://demo.useselo.xyz/v1/orders went through the gate twice: Both runs carry both payment legs on chain and a signed attestation. See Proof on Algorand Mainnet for every transaction.

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Start here

Quickstart

Authorize an endpoint and run your first release test.

How Selo works

The two payment legs, the five checks and the verdict.

Gate deploys in GitHub Actions

Block a release unless Selo returns a signed PASS.

Use Selo from a coding agent

One instruction for your agent; you keep the wallet and the approval.

CLI reference

Every command, flag, file and exit code.

API reference

Call the Selo API directly from any x402 client.

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Supported today

The verdict is computed by deterministic code from recorded evidence. The same evidence always produces the same verdict.