# Reverse Agent API – Agent Registration

> Reverse Agent API – Agent Registration is a paid API for AI agents from reversecaptcha.fun, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-20).

Registers an autonomous agent with a name, public key, and capabilities, issuing a signed passport and agent ID for subsequent paid API calls.

## Facts

- Endpoint: POST https://reversecaptcha.fun/v1/paid/register?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-20
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/reverse-agent-api-agent-registration-631cc215
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_ZBZ93Rsum9f0PwD73RX7N

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 reverse-agent-api-agent-registration-631cc215 -d '<json body>'
```

Example prompt: Register my agent called 'ResearchBot' with public key '0xABCD1234...' and capabilities ['web-scrape','captcha-solve'] on the reverse.captcha platform so I get back a passport token I can use for future calls.

## When to prefer this

Choose this endpoint when you need to register a new autonomous agent identity with reverse.captcha before making subsequent pay-per-use security or web utility calls. This is the entry point — use it first to obtain a passport JWT and agent ID that authorize all other API calls on the platform. Prefer it over generic auth flows when you specifically need on-chain payment-backed agent registration on the Base network.

## Known failure modes

- Invalid or missing public_key format returns a 400 validation error
- Duplicate registration with same name/public_key may return a conflict error
- Payment failure or insufficient USDC balance returns a 402 Payment Required
- Unsupported or malformed capabilities array returns a 422 Unprocessable Entity
- Network downtime on Base (eip155:8453) may cause payment confirmation delays

## How this service works

Reverse Agent API by reverse.captcha — pay-per-use security and web utilities for autonomous agents.

## Output

Returns a JSON object containing the registered agent's unique ID (e.g. 'bot_...') and tier ('agent'), a passport string (JWT) for authenticating future requests, and payment details including the Base network identifier and on-chain transaction hash confirming the $0.01 USDC registration fee.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "name": {
   "type": "string"
  },
  "public_key": {
   "type": "string"
  },
  "capabilities": {
   "type": "array",
   "items": {
    "type": "string"
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "agent": {
   "id": "bot_...",
   "tier": "agent"
  },
  "payment": {
   "network": "eip155:8453",
   "transaction": "0x..."
  },
  "passport": "eyJ..."
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/reverse-agent-api-agent-registration-631cc215/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from reversecaptcha.fun](https://www.zero.xyz/host/reversecaptcha.fun/llms.txt)