# PennyRail MIME Lookup — Extension to MIME Type

> PennyRail MIME Lookup — Extension to MIME Type is a paid API for AI agents from pennyrail.vercel.app, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-14).

Looks up the MIME type(s) associated with a given file extension using the mime-extensions mapping

## Facts

- Endpoint: POST https://pennyrail.vercel.app/api/p/nano/mime.lookup--mime-extensions
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/pennyrail-mime-lookup-extension-to-mime-type-d8b8d69e
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_58PDC_-__OQcluCDHyzm5

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 pennyrail-mime-lookup-extension-to-mime-type-d8b8d69e -d '<json body>'
```

Example prompt: What's the MIME type for .mp4 files? I need to know the correct content-type header value to serve them from my server.

## When to prefer this

Use this endpoint when you need a quick, programmatic lookup of the MIME type for a given file extension, especially in micropayment-native (x402) agent workflows where per-call billing is acceptable. Prefer over bundling a full mime library when operating in serverless or constrained environments.

## Known failure modes

- Unknown or unsupported file extension returns empty or null result
- Malformed input object causes validation error
- Payment failure via x402 prevents request from being processed
- Vercel cold start may add latency on first call

## How this service works

Machine-readable settlement service

## Output

Returns an object containing the MIME type string(s) associated with the provided file extension, suitable for use in HTTP Content-Type headers or file handling logic.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "object",
 "additionalProperties": true
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/pennyrail-mime-lookup-extension-to-mime-type-d8b8d69e/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from pennyrail.vercel.app](https://www.zero.xyz/host/pennyrail.vercel.app/llms.txt)