Coinbase has introduced x402, an open payment standard leveraging the long-dormant HTTP 402 “Payment Required” code, to enable machine-to-machine and AI agent payments using stablecoins across the web. Launched in May 2025, x402 allows APIs, apps, and autonomous software to pay directly for digital services without traditional accounts, API keys, or intermediaries. Payments are mainly made in USDC, the dollar-pegged stablecoin from Circle, settled on Coinbase’s layer-2 Base network with facilitators handling blockchain interactions. The protocol supports multiple networks, including Solana, Polygon, and Arbitrum, as well as traditional payment cards.
Bringing Payment to the Web’s Core Protocols
HTTP 402 was included in early internet standards as a placeholder for online payment systems but remained unused for three decades. By building on this legacy, x402 creates a native payment layer for the web, making it easier for autonomous agents to access resources and data. x402’s design allows a typical payment in seconds at a fraction of a cent, suitable for microtransactions requested by AI and other automated systems.
The protocol is structured as a set of rules governing messaging, headers, and an interaction flow between clients and servers. When a client requests data or services, the server replies with a “402 Payment Required” code, including machine-readable payment terms. The agent authorizes the payment with its wallet and resends the request, attaching the signature as proof. Settlement is handled by facilitators, meaning merchants are not required to manage their own crypto infrastructure.
Most onchain interactions use EIP-3009, a standard that lets users authorize transfers via signatures rather than onchain transactions, removing the need for buyers to hold network gas tokens such as ETH.
Mini dictionary: EIP-3009 – An Ethereum technical standard allowing off-chain token transfers via cryptographic signatures, enabling account holders to authorize payments without creating or signing direct blockchain transactions.
Growth, Backers, and Recent Adoption
The x402 Foundation, launched by the Linux Foundation in April 2026, now oversees the protocol’s vendor-neutral governance. Membership includes major technology and payments firms such as Visa, Mastercard, American Express, Google, Stripe, PayPal, Shopify, AWS, and Circle, with 57 organizations as of late 2026. Michael Hursta took over as the foundation’s executive director in October 2026. Coinbase, Stripe, and Cloudflare co-developed major components, while entities like CoinGecko, Agentic.Market, and AWS have integrated x402 into their services for crypto data, agent payments, and marketplace access.
By November 2026, x402 had processed more than 196 million transactions across twelve blockchains, settling over $42 million. Data from Fireblocks, citing agenteconomy.to, shows more than 97% of onchain agent transactions in the second quarter of 2026 involved x402. However, more than half of these transactions were concentrated in a two-month period in late 2025, largely due to automated trading around PING, a token issued through x402. Activity slowed later, with $274,000 in transactions processed in October 2026.
| Period | Transactions | Value Settled |
|---|---|---|
| Late 2025 (2 months) | Over 50% of total | Majority due to PING minting |
| October 2026 | 5.1 million | $274,000 |
| Total (Nov 2026) | 196 million+ | $42 million+ |
“Imagine a future where crypto is the native payment layer of the web—x402 turns the old 402 code into that missing infrastructure, powering payments for everything from API calls to digital content,” the Coinbase Developer Platform commented.
How x402 Works and Competing Protocols
x402 is not a blockchain or a cryptocurrency and does not have an official token. Payments are made with existing assets such as USDC. Some speculative x402 tokens have appeared on public chains but are not endorsed by Coinbase or the x402 Foundation.
To use x402, users or agents must hold supported stablecoins, usually USDC, in a compatible wallet on supported networks like Base. Large exchanges—Coinbase, Kraken, and Binance—offer USDC access and developers may fund agents through the Coinbase Developer Platform or Circle Wallets.
Competing protocols include the Agentic Commerce Protocol, developed by Stripe and OpenAI, and Visa’s Trusted Agent Protocol. Stripe and Tempo also co-created the Machine Payments Protocol (MPP), which extends the 402 concept and offers session-based billing. However, x402 remains a leading standard among agent-driven web payments.
“AI agents have become indispensable in today’s digital economy, and an open payment standard like x402 is critical to scalable agent commerce,” Sellers Commerce, an e-commerce research firm, reported, projecting the AI agent market to soar from $7.38 billion in 2023 to $47 billion by 2030.
