pay402

Buy anything behind an HTTP 402. No account, no API key, no browser.

Both rails are proven on mainnet, with this code, verified against the chain rather than against anyone's database:

	buyer	seller	fee wallet	splitter
Base	−$0.02005	+$0.01	+$0.01005	kept nothing
Solana	−$0.02005	+$0.01	+$0.01005	n/a — no splitter

On both, the buyer held no native gas token: on Base the relayer submits the EIP-3009 authorization, on Solana it signs as fee payer. The interface may still move before 1.0.

pip install "pay402[evm]"
pay402 https://api.checkout402.com/c/chk_abc123 --quote
pay402 https://api.checkout402.com/c/chk_abc123 --key $PAY402_KEY --max-usd 1.00

from pay402 import pay
goods = pay(url, private_key=os.environ["AGENT_KEY"], max_usd="1.00")

Reads the 402 challenge, picks a chain it can sign for, signs, retries with X-PAYMENT, and hands back the goods plus a receipt. Base (EIP-3009) and Solana (SPL) today.

Guardrails

max_usd is required for a live payment. An agent looping on a paid endpoint with no ceiling is the failure mode that matters, so the default is refusal rather than a permissive setting someone forgets to override. Nothing is signed until the quoted total has passed the cap.

On Solana the payee builds the transaction and you sign it, so pay402 decodes it and refuses unless it does exactly what the 402 advertised: two transfers, to the quoted wallets, for the quoted amounts, out of your token account and no other, with no third program involved. Non-custodial should mean more than "they cannot hold your funds".

If you paid and the goods did not arrive, the error carries the receipt id — the one thing you need to get it resolved.

Rehearse first

Every checkout has a test face — the same URL plus /test — where settlement is simulated: no chain, no funds, synthetic tx hash. Same call, two swaps:

pay(url + "/test", test_payer="0xAnyAddress")   # instead of a private key

The shapes are identical to a live payment, so code proven on the test face runs unchanged against the bare URL.

Extras

pay402[evm] for Base, pay402[solana] for Solana, pay402[all] for both. The base install is httpx only, so an agent sandbox will accept it.

MIT. Source: https://github.com/bitfent/checkout402