x402 payments

The x402 standard uses HTTP 402 to let agents pay for resources programmatically.

Category: Commerce
Standard: Emerging; Off by default, turn on in settings

0%Top 100 adoption0 of 90 sites implement it 0/9OverviewStalledNo meaningful support, or vendors have said no.

Who supports it

No agent or browser has announced support yet.

27 others: no evidence yet. See every agent and browser

What it checks

x402 revives the long-unused HTTP 402 Payment Required status. A paid endpoint answers an unpaid request with 402 and the payment terms; the agent pays and retries with proof of payment.

The extension requests /.well-known/x402 and /.well-known/x402.json, in that order, and passes on the first one that returns a non-empty JSON document. If neither is there, it checks whether the homepage response carries an X-402 or WWW-Authenticate header. Any WWW-Authenticate header counts, so a page behind HTTP authentication also passes.

Commerce protocols are new, and most sites have no reason to support them, so absence is N/A rather than a failure.

Results

Status	When
Pass	One of the paths returns a non-empty JSON document, or the homepage sends one of the headers
N/A	Nothing was found

How to fix

Implement the x402 flow on the endpoints you charge for, and publish a descriptor at /.well-known/x402 so agents can find out before they hit a 402. Serve it as JSON (Content-Type: application/json); the extension only confirms a JSON document is there and does not validate its contents.

These standards are still settling, so follow the protocol’s own documentation for what the descriptor should contain.

Support by agent and browser

Announced means the vendor’s own docs or announcement say so. Published is the date on the vendor’s own page, where it has one. Checked is the last time our weekly research found that page still saying so.

No agent or browser has announced anything about this yet.

No evidence yet27

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Names and marks belong to their owners and are used only to identify products. None of these vendors is affiliated with Sitebulb. Spotted something out of date? Send a correction.

Adoption on the top 100 sites

0 of 90 measured sites implement it

Scanned 23 Oct 2026 with the Sitebulb Labs extension, against the Tranco list (tranco-56Z8N). 10 sites couldn’t be measured (bot challenge or timeout) and are left out of the share.

9 Oct 2026 0% → 23 Oct 2026 0%

Overview

0/9

Stalled

No meaningful support, or vendors have said no.

How this rating is worked out0 of 9 points

Factor	Points	Why
Vendor support	0 / 3	0 vendors supporting, 0 partly or planned
Top-100 adoption	0 / 3	0% of measured sites
Spec maturity	0 / 3	Community proposal

8 or more points is Established, 5 to 7 is Gaining traction, 2 to 4 is Speculative and under 2 is Stalled. A feature is also Stalled when more vendors have said no than yes. Read the spec.

Community insights

No community insights for this feature yet.

Quotes are from public posts, checked against the original before they appear here. Suggest an insight, or ask for yours to be removed.