# WebRef MIME Type Lookup

> WebRef MIME Type Lookup is a paid API for AI agents from webref.johnaio281.workers.dev, paid per call via x402, $0.003/call, status unknown (last checked 2026-10-22).

Looks up MIME type information for a file extension or content-type string, returning canonical type, subtypes, and content-type matching guidance for HTTP responses

## Facts

- Endpoint: GET https://webref.johnaio281.workers.dev/api/web/mime_type?utm_source=zero.xyz
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-22
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/webref-mime-type-lookup-03954013
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_kQo37cOpOge8x3wOSXo5F

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 webref-mime-type-lookup-03954013
```

Example prompt: What MIME type and content-type header value should I use when serving a .wasm file over HTTP GET?

## When to prefer this

Use this endpoint when an AI agent needs to programmatically determine the correct MIME type or Content-Type header for a given file extension or media type without relying on local libraries or hardcoded mappings. Particularly useful in serverless or sandboxed agent environments where file-type libraries are unavailable. Prefer over generic web search when you need a structured, authoritative answer with HTTP-specific context.

## Known failure modes

- Unknown or unrecognized file extension returns a 404 or empty result
- Passing an unsupported HTTP method (not GET, HEAD, or DELETE) results in a validation error
- Malformed or missing required fields return a schema validation error
- Ambiguous extensions with multiple MIME types may return the most common match only

## How this service works

Web standards and time reference for AI agents: HTTP status codes with what the client should do, retry semantics, MIME types and content-type matching, request-method safety and idempotency, plus deadline arithmetic - time until a moment, weekday and business-day checks, duration conversion and Unix timestamps. Pay per call in USDC on Base via x402 or USDC on Tempo via MPP. No signup, no API key, no KYC.

## Output

Returns the canonical MIME type string (e.g. 'application/wasm'), associated file extensions, content-type matching rules, and guidance on correct usage in HTTP headers for the queried extension or type.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": {
      "def": {
       "type": "optional",
       "innerType": {
        "def": {
         "type": "string"
        },
        "type": "string"
       }
      },
      "type": "optional"
     },
     "extension": {
      "def": {
       "type": "optional",
       "innerType": {
        "def": {
         "type": "string"
        },
        "type": "string"
       }
      },
      "type": "optional"
     }
    }
   },
   "additionalProperties": false
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/webref-mime-type-lookup-03954013/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from webref.johnaio281.workers.dev](https://www.zero.xyz/host/webref.johnaio281.workers.dev/llms.txt)