x402 is an open payment standard that puts HTTP's long-unused "402 Payment Required" status code to work, so a website, API or AI agent can charge per request in a stablecoin such as USDC, with no account, API key or card. It runs on both Solana and Base, has no token of its own, and is now maintained by the x402 Foundation at the Linux Foundation rather than by Coinbase alone.

Last updated: October 9, 2026. Time-sensitive figures are dated where they appear, and sources are listed at the end.

Key takeaways

  • x402 is a protocol, not a coin. A server answers "402 Payment Required" with a price, the client signs a payment and retries, and the server delivers once the payment checks out.
  • Governance has moved to the x402 Foundation. The Linux Foundation announced it in early April 2026, and the Solana Foundation reports that it opened on July 14, 2026 with 40 member organizations. The code is Apache-2.0, and the Technical Steering Committee lists Coinbase, Cloudflare and Stripe.
  • Base and Solana are both supported on mainnet. As of October 2026, EVM chains such as Base have all four payment schemes; Solana has exact, upto and batch-settlement.
  • Batch settlement lets an agent deposit once and pay for many requests with off-chain vouchers. PayAI opened a public preview of facilitator support for it on Solana at the end of September 2026.
  • Be careful with market-share headlines. Trackers count different things, and one analysis estimated that 47% of x402 transactions up to late 2025 were not organic.

How x402 works

For decades, HTTP's 402 status code was "reserved for future use" and almost never used. x402 gives it a job. Here is the flow as the x402 repository describes it:

  1. A client (a browser, script or AI agent) requests something, such as an API endpoint.
  2. The server replies 402 Payment Required, with a PAYMENT-REQUIRED header listing what it accepts: price, token, network, payment scheme and where to send funds.
  3. The client picks one option, signs a payment and retries the request with a PAYMENT-SIGNATURE header.
  4. The server verifies the payment itself or through a facilitator, a service that verifies and settles payments on-chain.
  5. The server returns the resource with a PAYMENT-RESPONSE header reporting the settlement.

The standard has no built-in fee. You pay on-chain gas, and facilitators set their own fees; the x402 FAQ says many offer zero facilitator fees. Every payment is signed by the buyer, so a facilitator that tampers with it fails the signature check and cannot settle it. Prices are tiny: the FAQ uses $0.001 per request as an example, and one vendor report put the average x402 payment at $0.12 in December 2025.

Who runs x402 now

The x402 FAQ credits Coinbase Developer Platform with creating the standard. Control has since widened:

  • The main repository is now x402-foundation/x402. The old coinbase/x402 repository calls itself "a development fork", and the NOTICE file names the x402 Foundation as copyright holder.
  • In early April 2026, the Linux Foundation announced the x402 Foundation and the Solana Foundation said it was joining.
  • The Solana Foundation's July 2026 ecosystem roundup says the Linux Foundation opened the x402 Foundation on July 14, with Coinbase contributing the protocol, 40 member organizations, and the Solana Foundation as a premier member alongside Visa and Stripe.
  • A Technical Steering Committee file, added in May 2026, lists three participating organizations: Coinbase, Cloudflare and Stripe.
  • The FAQ is explicit that "you don't need any Coinbase products to use it."

Payment schemes and SDKs

A scheme is the rule for how money moves. The x402 SDK feature table lists four as of October 2026:

Scheme What it does Base (EVM) Solana (SVM)
exact Pays a fixed amount per request Yes Yes
upto Authorizes a maximum, then charges actual usage Yes Yes (TypeScript, Go)
batch-settlement Deposit once, pay with off-chain vouchers, settle later Yes Yes (TypeScript, Go)
auth-capture Holds funds, then captures, voids or refunds them Yes (TypeScript, Go) Not listed

Developers use the @x402/evm package for Base and @x402/svm for Solana, plus server middleware (Express, Hono, Next.js and Fastify), fetch and axios clients, and Python and Go SDKs. On Base, a USDC payment uses EIP-3009 and needs a single off-chain signature; Permit2 is the fallback that lets other ERC-20 tokens work. On Solana, any SPL or Token-2022 token can be used.

Where x402 is already used

  • AI traffic on AWS. In June 2026, AWS WAF, Amazon's web application firewall, added AI traffic monetization for CloudFront: a new Monetize rule action charges AI agents via x402. AWS's sample deployment takes USDC on Base or Solana, and the Solana Foundation's June roundup described it as letting publishers set per-request prices and receive USDC.
  • Pay-per-crawl on Cloudflare. The x402 specs define a cloudflare:402 network whose setup step points to Cloudflare's pay-per-crawl documentation. Crawlers sign their requests, and Cloudflare acts as merchant of record, billing each crawler's registered identity in batches. This version is credit-backed and settles in US dollars through traditional rails, not with per-request on-chain payments.
  • Agent wallets on Base. Base MCP connects assistants such as Claude, ChatGPT and Cursor to a user's Base Account. Its Base documentation describes paying x402 APIs in USDC on Base, with every write action needing the user's approval. In September 2026 the docs moved to Coinbase Developer Platform, where the product is now called Wallet MCP.
  • Agent wallets on Solana. The Solana Foundation's August 2026 roundup says Ramp began testing agent wallets in a limited alpha that lets businesses fund wallets, set spending controls and record x402 purchases made by AI agents on Solana.
  • Paid AI and data APIs. BlockRun sells AI model calls and market data per call in USDC via x402 on Solana or Base; its wallet billing needs no account or API key.

Solana vs Base: who is actually winning?

Headline numbers rarely measure the same thing. Before you repeat one, check four things:

  • Transactions or dollars? A flood of sub-cent API calls can put one chain ahead on count while another leads on dollar volume.
  • Which period? In a market this young, a four-week window and a full quarter can tell opposite stories.
  • Who is counting? Indexers usually watch known facilitator addresses, so they can miss payments a server settles itself, and batching rolls many payments into one transaction. Many published figures also come from a chain's own foundation or from companies that sell x402 services.
  • Is it organic? Teams have padded activity to climb public leaderboards.

Here is what some published figures actually measure:

Figure Published by What it measures
23.2M x402 transactions, 76% of tracked transactions Solana Foundation, September 2026 roundup (citing Coinness) Solana's share of transaction count, August 22 to September 19, 2026
More than 35M transactions and $10M in volume Solana Foundation, July 2026 roundup Cumulative x402 activity on Solana since launch
About 63M transactions and $7.5M in USDC BlockRun, "State of x402" (December 2025) USDC transfers through known facilitator addresses on Base and Solana over 30 days
Base 53.3%, Solana 36.6% BlockRun (December 2025) Share of registered endpoints, not payments or dollars
47% of transactions and 14% of dollar volume "non-organic" Artemis estimate, cited by BlockRun Cumulative activity up to late 2025

BlockRun, which sells x402 services on both chains, also cites about $298K in total transacted value in the same report without reconciling it with its $7.5M headline. That is not a knock on one firm; early market data often looks like this. Our read as of October 2026: both chains carry real x402 traffic, figures cited by the Solana Foundation put Solana ahead on transaction count in late summer 2026, and we have not found an independent, audited dollar-volume comparison of the two chains.

Batch settlement: why micropayments got cheaper

The batch-settlement spec exists for cases where "gas fees exceed the value of individual requests" or block confirmation time is too slow for an HTTP response. The escrow version works like this:

  1. The agent deposits funds once into an on-chain channel.
  2. Each request carries a signed voucher with a running total. The server checks it off-chain and responds right away.
  3. The seller later claims the latest voucher on-chain; on EVM chains, claims from several channels can share one transaction. Unused deposit goes back to the buyer through a cooperative refund or, as a fallback, a timed withdrawal.

On Solana, this runs on the Solana Foundation's payment-channels program. The foundation launched Payment Channels in September 2026 with support for x402's upto and batch-settlement schemes, named Alibaba Cloud as a launch partner, and reported more than 1 million off-chain payments per second in its own benchmark. The official @x402/svm package includes batch settlement from version 2.28.0.

PayAI opened a public preview of facilitator support at the end of September 2026. As of early October, it is limited to USDC on Solana mainnet, deposits of 0.01 to 100 USDC per new channel, and 1,000 sponsored channels in total, and PayAI says admission can pause when capacity runs out. On Base, batch settlement ships in the EVM SDKs, and Base's docs include a guide to batching high-frequency payments.

PayAI's docs add two warnings: a successful claim "is not merchant payment" until a separate distribution reaches your USDC account, and a customer's reusable channel authorization is a bearer credential that must be protected like a secret.

What builders and token projects can do with x402

If you run a service, x402 lets you charge per API call, article, dataset or bot action, on whichever chain your users hold USDC. Use upto for metered work such as AI inference, and auth-capture on Base when buyers need refunds.

x402 needs no token of its own. The protocol accepts any ERC-20 on Base and any SPL or Token-2022 token on Solana, but the tools covered here, such as AWS WAF's monetization, Base MCP and PayAI's batch preview, use USDC. For background on those dollars, see our guide to stablecoins on Solana and Base.

Where a community token fits: next to the paid service, not inside it. A creator with a token on Solana could run a research bot priced at $0.02 per query in USDC on the same chain. The token stays a community asset, and the service earns stablecoins.

Where it does not fit: pricing the service in your own token makes prices swing with the market, and agents are unlikely to hold it. Be wary, too, of claims that x402 revenue automatically makes a token worth more. It does not.

If you are still at the token stage, our guide to creating a token on Solana or Base walks through it, and you can swap into USDC on either chain through the third-party widgets on our swap page. Solbase is non-custodial and handles the token launch only; it does not run x402 services, provide liquidity, or list, market or endorse tokens.

Caveats

  • Inflated traffic and interested sources. Leaderboard gaming and test traffic padded early numbers, and much of the published data comes from chain foundations or companies tied to x402 services.
  • No undo button. An exact payment is irreversible once executed. Refunds need the seller to send money back, or a scheme with refunds built in, such as auth-capture.
  • Agent wallet safety. Keep a human approving every write, cap channel deposits, and never give an agent a wallet holding your main funds.
  • Production setup. The x402 docs present the public x402.org facilitator as a testnet and quickstart tool. For mainnet, use a production facilitator, run your own or settle payments yourself.
  • Previews are previews. Solana batch settlement is new, and PayAI's facilitator support is a capped public preview whose limits can change.

FAQ

Is x402 a cryptocurrency or token?

No. x402 is an open payment protocol under the Apache-2.0 license. Payments move in existing tokens, usually USDC, and there is no x402 coin, so treat anything sold as an "x402 token" with suspicion.

Does x402 work on Solana and Base?

Yes. The x402 docs list both as mainnet networks, with @x402/evm covering Base and @x402/svm covering Solana. As of October 2026, Solana supports the exact, upto and batch-settlement schemes; auth-capture is listed for EVM chains only.

Which stablecoin does x402 use?

USDC is the usual choice: AWS WAF's monetization feature, Base MCP and PayAI's Solana preview all use it. But the protocol accepts any ERC-20 on Base and any SPL or Token-2022 token on Solana, and each seller decides what it takes.

Is x402 only for AI agents?

No. The docs name both human developers and AI agents as buyers, and list paywalls for digital content among the use cases. Agents get most of the attention because x402 lets them pay without creating accounts or entering card details.

Who controls the x402 standard?

The x402 Foundation at the Linux Foundation, announced in April 2026 and opened on July 14, 2026, according to the Solana Foundation. Its Technical Steering Committee lists Coinbase, Cloudflare and Stripe, and Coinbase's own repository is now a development fork of the foundation's.

Sources