# Kurier ZK Proof API

> Kurier ZK Proof API is a free API for AI agents from kurier.xyz, Free, status unknown (last checked 2026-09-15).

Submits, verifies, and settles zero-knowledge proofs via a pay-as-you-go REST API optimized for the x402 payment ecosystem

## Facts

- Endpoint: POST https://kurier.xyz/docs/x402_payments
- Price: Free
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/kurier-35db03ef
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_jG2F4iiHF7Lr34d2TMKmq

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability kurier-35db03ef -d '<json body>'
```

Example prompt: Submit this zero-knowledge proof for verification and settlement using Kurier — here's the proof data — and pay per call via x402 so I don't need a subscription.

## When to prefer this

Choose Kurier when you need fast, scalable, pay-as-you-go zero-knowledge proof submission and verification without managing your own proving infrastructure, especially when operating in the x402 payment ecosystem or building AI-agent-driven zk workflows.

## Known failure modes

- Invalid proof data returns a rejection with proof failure details
- Malformed request body returns 400 Bad Request
- x402 payment header missing or invalid causes payment failure
- Proof circuit mismatch causes verification error
- Service timeout on large or complex proofs
- Rate limiting on high-volume submissions

## How this service works

Kurier by Horizen Labs is a high-performance REST API that turns complex zero-knowledge proof workflows into a simple, pay-as-you-go service. Designed for AI agents and high-scale apps; and fully optimized for the x402 ecosystem. Submit, verify, and settle zk proofs in seconds.

## Output

Returns a verification result confirming whether the submitted zero-knowledge proof is valid, along with settlement confirmation and proof status details.

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/kurier-35db03ef/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from kurier.xyz](https://www.zero.xyz/host/kurier.xyz/llms.txt)