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Open source payment rails
Open source payment rails lists 6 Payment rails entries in alphabetical order. Payment rails marked open source, listed alphabetically by name. Nothing on the page is scored. The names are AP2, L402, Machine Payments Protocol, Polygon Agent CLI, Stripe link-cli, x402.
Last verified 2026-10-16 to 2026-10-19
Sources
- AP2 protocol documentation
- Google Cloud announcement of AP2
- AP2 v0.2.0 release on GitHub
- Lightning Labs L402 documentation
- MPP protocol site
- Stripe documentation for MPP
- Polygon Agent CLI reference
- Polygon Agent CLI package
- stripe/link-cli README
- Enable agents to spend
- x402 site
- Coinbase documentation for how x402 works
6 listingsPayment rails
| Name | Status | Open source | Mechanism |
|---|---|---|---|
| AP2 | Beta | Yes | Open payment extension for A2A and UCP that records checkout and payment authorization as signed mandates. Public samples exist while FIDO continues the standards work. mandates, cards, stablecoins |
| L402 | Live | Yes | HTTP 402 flow that pairs a macaroon with a Lightning invoice. The client pays, then presents the preimage so the server can check payment without a lookup. http-402, lightning, macaroons |
| Machine Payments Protocol | Live | Yes | Open HTTP 402 protocol, co-authored by Stripe and Tempo, so an agent can authorize payment for an API with a card or a stablecoin and receive a receipt. http-402, cards, stablecoins |
| Polygon Agent CLI | Live | Yes | Agent CLI with an embedded smart wallet. Session mode spends only inside an allowance the owner approves, x402 payments can be capped per call, and session logout revokes that install. wallets, spend-limits, http-402 |
| Stripe link-cli | Live | Yes | CLI for an agent to request a card purchase or a Machine Payments Protocol charge. Link asks the customer to approve the spend request, then returns a one time payment credential. cards, spend-limits, http-402 |
| x402 | Live | Yes | Open HTTP payment standard. A server answers with status 402, the client pays and retries, and a facilitator can verify and settle the payment. http-402, stablecoins, pay-per-call |
Questions
- How many listings match Open source payment rails?
- 6 listings match. The list is alphabetical.
- Which listings are on Open source payment rails?
- AP2, L402, Machine Payments Protocol, Polygon Agent CLI, Stripe link-cli, x402.
Comparisons
Pairs in this filter where both listings have source URLs.