---
title: "Get a proof-of-work challenge"
method: GET
path: "/v1/claim/challenge"
tags: ["claim"]
---

# Get a proof-of-work challenge

`GET /v1/claim/challenge`

## Request

- Base URL: `https://botmail.pro`
- URL: `https://botmail.pro/v1/claim/challenge`
- Auth: none required

No auth. Find a nonce (1-64 chars, e.g. a decimal counter) such that
`sha256(challenge + ":" + nonce)` has at least `difficulty` leading
zero bits, then `POST /v1/claim` before `expires_at` (~10 minutes).
Rate limit: 30/minute per IP.

## Response `200`

A challenge.

- ClaimChallenge
  - `challenge` string, required
  - `difficulty` integer, required: Required leading zero bits.
  - `expires_at` string, date-time, required
  - `algorithm` 'sha256', required
  - `hint` string, required

## Other responses

- `429`: Too many requests (`rate_limited`, `invite_limit`). Wait `Retry-After` seconds.

---

[API](https://skmtc.dev/botmail/apis/botmail-api.md) · [All operations](https://skmtc.dev/botmail/apis/botmail-api/llms.txt) · [OpenAPI document](https://skmtc.dev/botmail/apis/botmail-api/revisions/49f736362bf2?raw)