# Delx Content Type Guess

> Delx Content Type Guess is a paid API for AI agents from api.delx.ai, paid per call via x402, $0.003/call, status unknown (last checked 2026-09-15).

Guesses the MIME type for a given filename, file path, or URL based solely on its extension

## Facts

- Endpoint: POST https://api.delx.ai/api/v1/x402/content-type-guess
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/delx-content-type-guess-5b1f2f28
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_lerjwC4UeKUQibO1rVbCr

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 delx-content-type-guess-5b1f2f28 -d '<json body>'
```

Example prompt: What MIME type should I use for a file called 'report.xlsx'? Just give me the content-type string based on the extension.

## When to prefer this

Use this endpoint when you already hold a filename, path, or URL and need a quick, deterministic, stateless MIME type guess purely from the extension — no file content is read and no network fetch is performed. Prefer it over manual lookup tables or regex when you need a consistent, machine-readable JSON result integrated into a workflow. Not suitable if you need to detect content type from actual file bytes or magic numbers.

## Known failure modes

- Unknown or uncommon extension returns a generic fallback MIME type such as 'application/octet-stream'
- Filename with no extension may return null or a default type
- Ambiguous extensions shared by multiple MIME types may return the most common mapping rather than the precise one
- Malformed input (empty string) may return an error or default

## How this service works

Guess a MIME type from a filename, path, or URL extension — call when guessing MIME type from an extension. Use on text/URLs the agent already holds—adjacent to high-volume extract demand, never advertised as general web or X search. Returns deterministic machine-readable JSON for $0.003 USDC via x402 on Base. Execution is first-party, local-only, stateless, and memory-only with no paid upstream, no input retention, and no claim of live chain tip, web search, or media generation. Results are ad…

## Output

A deterministic JSON object containing the guessed MIME type string (e.g. 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet') derived from the file extension in the provided filename, path, or URL. No network calls are made; the result is computed locally from extension-to-MIME mappings.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "filename": {
   "type": "string",
   "description": "Filename, path, or URL used only for extension/MIME guess."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "known": true,
  "schema": "delx/util-content-type-guess/v1",
  "filename": "report.PDF",
  "extension": "pdf",
  "content_type": "application/pdf"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/delx-content-type-guess-5b1f2f28/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.delx.ai](https://www.zero.xyz/host/api.delx.ai/llms.txt)