# Proof Random API – drand Beacon Evidence Endpoint

> Proof Random API – drand Beacon Evidence Endpoint is a paid API for AI agents from proof-random-api.pn-26f.workers.dev, paid per call via x402, $0.15/call, status unknown (last checked 2026-10-22).

Relays a verifiable drand quicknet randomness beacon with nonce-bound reproducible sampling, returning cryptographic evidence for a given question

## Facts

- Endpoint: POST https://proof-random-api.pn-26f.workers.dev/v1/evidence?utm_source=zero.xyz
- Price: $0.15/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-22
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/proof-random-api-drand-beacon-evidence-endpoint-819252c5
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_LwdDJYtep-yQ83UhEXc9-

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 proof-random-api-drand-beacon-evidence-endpoint-819252c5 -d '<json body>'
```

Example prompt: I need a cryptographically verifiable, nonce-bound random evidence sample from the drand quicknet beacon for the question 'which winner gets the prize in round 42 of our lottery?' — I'll verify the BLS proof on my end.

## When to prefer this

Choose this endpoint when you need publicly verifiable, tamper-resistant randomness backed by the drand quicknet beacon and you are able to perform client-side BLS verification. It is ideal for provably fair draws, on-chain random seeds, and audit-grade random assignments where trust-minimized, reproducible randomness is required. Prefer this over centralized RNG APIs when cryptographic verifiability and nonce-binding to a specific question are essential requirements.

## Known failure modes

- Missing required 'question' field returns 400 Bad Request
- drand network unavailability causes relay failure or timeout
- Invalid sources array format may result in a 422 or ignored field
- BLS verification failure on client side if beacon data is malformed
- Payment not confirmed via x402 protocol results in 402 Payment Required

## How this service works

A free drand quicknet beacon relay with nonce-bound reproducible sampling. Client-side BLS verification required.

## Output

Returns a cryptographic evidence payload containing the drand quicknet beacon round data, a BLS-verifiable randomness value, and a nonce binding it to the submitted question. The client is expected to perform BLS signature verification independently to confirm authenticity.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "required": [
  "question"
 ],
 "properties": {
  "sources": {
   "type": "array"
  },
  "question": {
   "type": "string"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/proof-random-api-drand-beacon-evidence-endpoint-819252c5/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from proof-random-api.pn-26f.workers.dev](https://www.zero.xyz/host/proof-random-api.pn-26f.workers.dev/llms.txt)