Introducing the Public x402 Playground: test paid API flows in minutes

web3luka
Feb 22, 2026 · 2 min read

We just launched a public x402 Playground at relai.fi/playground.

The goal is simple: help developers validate paid API flows fast, without going through full dashboard setup every time.

The problem we wanted to solve


Before this, quick testing still had friction:

  • You often had to enter authenticated dashboard flow just to run a payment test

  • Sharing reproducible test setups across team members was slower than it should be

  • Debugging wallet-specific issues (signing, network mismatch, token selection) took too many steps

For teams building paid APIs, this slowed down the shortest and most important loop:

change config → test payment → inspect result → fix → retest

What this solves in practice

1) Faster first success

New users can run a realistic payment test immediately, instead of doing account + dashboard navigation first.

2) Better debugging workflow

You can quickly isolate issues in signing and settlement flow, verify network/token combinations, and iterate faster.

3) Easier collaboration

A public route makes it easier for product, support, and engineering to reproduce the same payment scenario.

Why this matters now

As payment support expands across chains and tokens, integration complexity naturally grows. A dedicated playground keeps that complexity manageable by giving developers one place to:
  • validate payment behavior
  • compare transport and signing paths
  • confirm expected UX before shipping to end users
In short: fewer surprises in production, faster shipping in development.

Available now

Open the playground and run your own test flow:
  • https://relai.fi/playground
If you’re building paid APIs on RelAI, this is now the fastest way to verify your x402 integration end to end.
Build faster, debug earlier, and ship paid API flows with confidence.

Understand x402 before you implement

This guide uses payment primitives from the x402 standard. Read the protocol overview for a complete flow, terminology, and integration FAQ.