---
title: "x402 Header Decoder, Payload Linter & 402 Flow Simulator"
method: POST
path: "/v1/tools/simulate_x402_flow"
tags: ["TODO_TAGS_REVIEW", "TODO_AP2_EXPORT_REVIEW"]
---

# x402 Header Decoder, Payload Linter & 402 Flow Simulator

`POST /v1/tools/simulate_x402_flow`

## Request

- Base URL: `https://ainumbers.co`
- URL: `https://ainumbers.co/v1/tools/simulate_x402_flow`
- Auth: none declared

Decodes base64 PAYMENT-REQUIRED / PAYMENT-SIGNATURE / PAYMENT-RESPONSE headers, lints exact-scheme PaymentPayload (EIP-3009 style authorization fields), walks the HTTP-402 request/verify/settle flow, shows scheme×network matrix. Branch B, node 2 of the Agentic Rail Chain. Promoted from T277.

**Tool URL:** https://ainumbers.co/chaingraph/art-26-x402-payload-decoder-flow-simulator.html

## Request body

- object
  - `header_or_payload` unknown, required
  - `payload` string: type not evidenced by kernel source

## Response `200`

Successful tool execution result

- object
  - `decoded_type` string
  - `errors` integer
  - `findings` object[]
    - `level` string
    - `msg` string
  - `has_accepts` boolean
  - `is_json` boolean
  - `mode` string
  - `network` string
  - `passes` integer
  - `scheme` string
  - `score` integer
  - `warnings` integer

---

[API](https://skmtc.dev/ainumbers/apis/ainumbers-co-fintech-intelligence-suite.md) · [All operations](https://skmtc.dev/ainumbers/apis/ainumbers-co-fintech-intelligence-suite/llms.txt) · [OpenAPI document](https://skmtc.dev/ainumbers/apis/ainumbers-co-fintech-intelligence-suite/revisions/b462e4f5bb28?raw)