# x402

[7 · Pay](/category/pay/)

| x402 |
| --- |
| Category | [Pay](/category/pay/) |
| Governed by | x402 Foundation, a Series of LF Projects, LLC (Linux Foundation); operational launch announced 2026-07-14 |
| Status | Open, neutral standard for internet-native payments |
| Phase | living |
| Implementation | multi-implementation |
| Adoption | claimed — x402 Foundation (x402.org live dashboard) |
| Version | x402 protocol specification v2, transports-v2/http.md |
| Specification | [https://github.com/x402-foundation/x402/blob/main/specs/transports-v2/http.md](https://github.com/x402-foundation/x402/blob/main/specs/transports-v2/http.md) |
| Found at | none — signalled per-request via the 402 status code, not a fixed well-known path |
| Last checked | 2026-09-06 |

[Pay](/category/pay/) x402 is an open, HTTP-native payment protocol that activates the long-reserved (since 1999) HTTP 402 "Payment Required" status code: a server responds 402 with machine-readable payment requirements, the client pays (in practice, stablecoins over an EVM-compatible network) and retries the request with proof of payment attached [[1]](#ref-1). It solves instant, account-free, per-request monetization for APIs and agentic consumers — no signup, no KYC, no stored API keys, no prepaid credit balance — collapsing what the project calls a five-step "old way" of API onboarding into three HTTP round trips [own site, x402.org homepage].

## Overview
It does not itself define a payment network; it is a wire-format and challenge/response convention that networks and asset issuers plug into via a scheme and network field (the reference implementation targets EVM chains and USDC, per the transport spec's example payload) [[1]](#ref-1). Version 2 of the specification moved the payment-required and payment-signature payloads into dedicated PAYMENT-REQUIRED and PAYMENT-SIGNATURE HTTP headers rather than embedding them in earlier v1 conventions, and the specification separately defines non-HTTP transports (the repository lists transports-v1 and transports-v2 directories) [[1]](#ref-1).

As of this verification, x402 is governed by the x402 Foundation, described in its own site footer as "a Series of LF Projects, LLC" — i.e., a Linux Foundation-hosted project — with an operational launch announced by the Linux Foundation on 2026-07-14 [[2]](#ref-2). Coinbase originated the protocol; the Foundation now governs it independently of any single company, per the project's own framing [x402.org homepage]. The site's homepage displays a real-time usage dashboard claiming 75.41M transactions and $24.24M in volume over the trailing 30 days, with 94.06K buyers and 22K sellers, current as of this check [[3]](#ref-3) — but this figure is self-reported by the Foundation running the protocol, not measured by an independent index, so it is recorded here as claimed rather than observed or measured. What remains open: no independently operated adoption index (e.g. a third-party "402 index") was located and fetched during this verification to cross-check the Foundation's own dashboard number.

## Discovery and probe

HTTP 402 response carrying payment requirements in a header · none — signalled per-request via the 402 status code, not a fixed well-known path

```
GET {origin}/{paid-path}
parse:     HTTP 402 status with a base64-encoded PaymentRequired object in the PAYMENT-REQUIRED response header (x402 v2 HTTP transport)
on absent: A 200 or a 402 without a PAYMENT-REQUIRED header means this specific path is not (or no longer) gated by x402 v2 over HTTP; the same origin could still use x402 over the MCP or other transports, or the legacy v1 header shape, so the probe only rules out v2/HTTP on the probed path.
```

Not probed live: no-fixed-path. A 402 challenge appears only on a URL that charges; there is no fixed path to check.

## History
- 2026-09-05 — seeded from Exa Agent research run
- 2026-09-06 — verified against x402.org (homepage, /announcement), x402-foundation/x402 specs/transports-v2/http.md

## Instances

- [Stripe](https://docs.stripe.com/payments/machine/x402) · Recorded 2026-09-07 · business
- [Coinbase (originator)](https://x402.org) · Recorded 2026-09-06 · business
- [x402 Foundation (Linux Foundation, LF Projects LLC)](https://x402.org/announcement) · Observed 2026-07-14 · business
- [x402 Foundation (Linux Foundation)](https://www.linuxfoundation.org/press/linux-foundation-announces-operational-launch-of-x402-foundation-to-standardize-internet-native-payments-for-ai-agents-and-applications) · Observed 2026-07-14 · registry
- [Fireblocks](https://github.com/fireblocks/x402-facilitator) · Observed 2026-05-18 · service
- [Nevermined](https://facilitator.live.nevermined.app) · Observed 2026-05-09 · service
- [Coinbase](https://github.com/coinbase/x402) · Observed 2026-04-02 · business
- [Circle](https://www.circle.com/blog/a-deep-dive-into-circle-nanopayments-gas-free-usdc-transfers) · Observed 2026-03-20 · business

Every instance with its source is listed on the [instances page](/instances/).

## See also

- [L402](/protocols/l402/)
- [Machine Payments Protocol](/protocols/mpp/)
- [s402](/protocols/s402/)

- [Facilitator](/terms/facilitator/)

## References

- x402's HTTP transport spec defines the 402 challenge as HTTP 402 status with a PAYMENT-REQUIRED header carrying a base64-encoded PaymentRequired object, and the client retry as a PAYMENT-SIGNATURE header carrying a base64-encoded PaymentPayload. — [https://raw.githubusercontent.com/x402-foundation/x402/main/specs/transports-v2/http.md](https://raw.githubusercontent.com/x402-foundation/x402/main/specs/transports-v2/http.md) VERIFIED
- x402.org's footer identifies the project as 'x402 a Series of LF Projects, LLC', confirming Linux Foundation stewardship, and its Announcements page states the Linux Foundation announced the operational launch of the x402 Foundation on July 14, 2026. — [https://x402.org/announcement](https://x402.org/announcement) (2026-07-14) VERIFIED
- x402.org's homepage displays a live self-reported dashboard: 75.41M transactions and $24.24M volume in the last 30 days, 94.06K buyers and 22K sellers, at time of check. — [https://x402.org](https://x402.org) (2026-09-06) VERIFIED

[JSON](/data/protocols/x402.json) · [Markdown](/protocols/x402/index.md)