---
title: "About x402aff"
description: "x402aff is an open-source, MIT-licensed kit for builder-code affiliation on x402. Built by Aaron Elijah Mars for MiroShark."
canonical: https://www.x402aff.xyz/about
last-updated: 2026-09-30
---

# About x402aff

> x402aff is an open-source, MIT-licensed kit for builder-code affiliation on x402. Built by Aaron Elijah Mars for MiroShark.

## What it is

x402aff is builder-code affiliation for x402, the HTTP 402 payment protocol. When an app sends a paying user to your x402 API, the kit routes that payment into an ownerless 0xSplits contract whose recipients and ratio are fixed at its address: by default 10% to the builder whose app drove the payment and 90% to you. Nobody, including you, can redirect the builder's cut, which is what makes it a credible offer rather than a promise.

It is a library, not a service. It ships as the x402aff package on npm and PyPI, runs inside your own server, deploys no contracts of its own, and needs no private key. Settlement goes through the stock CDP facilitator on Base mainnet, and payouts are released by a permissionless distribute call that anyone can trigger.

## Who builds it

x402aff is built by Aaron Elijah Mars for MiroShark, which runs it in production on its own x402 endpoint and publishes a live claims dashboard for it. The code, tests, and issue tracker are public on GitHub under the MIT License.

- [Aaron Elijah Mars](https://aaronjmars.com)
- [MiroShark](https://www.miroshark.xyz)
- [Live claims dashboard](https://www.miroshark.xyz/x402aff)

## What it builds on

- x402: the open HTTP 402 payment standard for paid APIs.
- Base Builder Codes: the on-chain registry that tags a paid request with a (the API), s (the builder), and w (the facilitator).
- 0xSplits v2 PushSplit: the audited, immutable split contract that holds and pays out each builder's share.

- [x402](https://x402.org)
- [Base Builder Codes](https://docs.base.org/apps/builder-codes/builder-codes)
- [0xSplits](https://splits.org)