Base Builder Codes have now launched for x402 apps, giving Base developers a new way to link payment activity to their projects. The Coinbase Layer-2 network said the tool adds on-chain attribution. It targets x402 usage across AI agent payments.
The Base team announced the rollout in an X post on Monday. It said the codes add the ERC-8021 schema 2 data to settlement transaction call data. That record can be used to determine which apps are causing or benefiting x402 payments in Base.
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Base Builder Codes Link x402 Payments to Apps
Base Builder Codes are used to identify developer projects. Each code is issued as an ERC-721 NFT and is claimable via the Base dashboard. The developer can specify a custom name or an alphanumeric code to a maximum of 32 characters.
Once integrated, the code is affixed to x402 payment settlements on Base. This provides teams a reliable history of activity associated with their apps. System to allow for app-level analytics and future rewards for builders.
Base Builder Codes apply to both legs of an x402 transaction as well. The buyer-side client can pass on the attribution with the payment. A seller-side resource server can receive credit upon completion of a paid resource request as well.
The feature comes as x402 is getting noticed by payment & web infrastructure companies. The protocol resurrects the old HTTP 402 “Payment Required” status code for Internet-native payments. Enables apps and AI agents for small, online payments, typically using USDC.
Developers might be able to use Base Builder Codes to monitor x402 traffic in more detail. Teams can view the level of activity generated through their apps’ services. They can also indicate which tools are finishing paid requests on the network.
Developers Get Faster x402 Setup Through Coinbase Platform
Base said the setup is designed to be quick for developers. Teams can request a code and then review documents provided by the Coinbase Developer Platform for x402 clients or servers. The company said AI coding tools can use the same instructions to help with implementation.
In April 2026, the x402 effort found support in the broader effort. The x402 Foundation is joined by Coinbase, Stripe, and Cloudflare that will help craft a common standard for online payment. Their participation shifted the attention to machine-to-machine payments and stablecoin settlement.
Base Builder Codes are also linked to possible rewards for builders. The x402 activity attributed to Base can be used for future incentive programs. For developers, that means that proper transaction labeling will be crucial if reward systems are extended to include usage data as part of Base’s broader app-level reporting.
Those codes now have a more defined layer of attribution thanks to Base Builder Codes. The tool is capable of measuring developer usage without off-chain reporting for x402 apps within Base. Its impact will depend on how many teams adopt x402 and register their codes.
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