# Blinded Macaroon Signer MCP

> Blinded Macaroon Signer MCP is a paid API for AI agents from api.m2mcent.com, paid per call via x402, $0.25/call, status unknown (last checked 2026-09-15).

Signs a blinded macaroon token, enabling privacy-preserving authentication and authorization workflows.

## Facts

- Endpoint: POST https://api.m2mcent.com/blinded-macaroon-signer-mcp/api/process
- Price: $0.25/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/blinded-macaroon-signer-mcp-c477587d
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_kGsByAUMbF3TbQwfo70yY

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 blinded-macaroon-signer-mcp-c477587d -d '<json body>'
```

Example prompt: Can you blind-sign this macaroon token data for me so I can use it in a privacy-preserving authentication flow? Here's the blinded data string to process.

## When to prefer this

Choose this endpoint when you need a cryptographic blind-signing service for macaroon tokens — specifically when implementing privacy-preserving authentication flows where the signer must not learn the content of the token being signed. Prefer this over standard macaroon signing when anonymity or unlinkability between the signing and usage phases is a requirement.

## Known failure modes

- Invalid or malformed blinded macaroon data returns an error response
- Empty or missing 'data' field causes a validation failure
- Malformed base64 or encoding issues in the input string may cause processing errors
- Payment failure or insufficient funds results in a 402 response before processing
- Oversized input data may be rejected with a payload-too-large error

## How this service works

The premier global index of 1,069 monetized MCP nodes across 205 specialized subdomains. Gasless USDC runtime settlements via x402 V2 Spec on Base L2. Save 95% token context.

## Output

Returns a signed version of the submitted blinded macaroon data, which the requesting party can then unblind to obtain a valid, issuer-signed macaroon credential usable for authentication or authorization.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "payload": {
   "type": "string"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "success": true
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/blinded-macaroon-signer-mcp-c477587d/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.m2mcent.com](https://www.zero.xyz/host/api.m2mcent.com/llms.txt)