Free file format JSON API

Every one of the 289 formats in the database is available as plain JSON. The API is fully static, so it is fast, free and never goes down under load. Use it in your own apps, scripts or docs. A link back to WhatFileType is appreciated but not required.

Endpoints

Get one format

Returns the full record for a single extension.

GET https://whatfiletype.com/api/format/{ext}.json

Example:

curl https://whatfiletype.com/api/format/heic.json

List all formats

Returns an index of every format with links to each full record.

GET https://whatfiletype.com/api/formats

File signatures dataset

The complete magic-numbers reference as one JSON file: every signature with its hex bytes, offset, the formats that share it and a link to its page.

GET https://whatfiletype.com/api/signatures

Example response

{
  "ext": "heic",
  "name": "HEIC",
  "fullName": "High Efficiency Image Container",
  "category": { "key": "image", "label": "Image" },
  "mimeTypes": ["image/heic", "image/heif"],
  "binary": true,
  "signatures": [
    { "hex": "66 74 79 70 68 65 69", "offset": 4, "note": "ftyp box, brand starts with 'hei'" }
  ],
  "convertTo": ["JPG", "PNG", "WebP"],
  "safety": "Safe. HEIC is a plain image container ..."
}

Use it from JavaScript

const res = await fetch("https://whatfiletype.com/api/format/webp.json");
const data = await res.json();
console.log(data.mimeTypes); // ["image/webp"]

Use it from Python

import urllib.request, json

url = "https://whatfiletype.com/api/format/parquet.json"
with urllib.request.urlopen(url) as r:
    data = json.load(r)
print(data["signatures"])  # [{"hex": "50 41 52 31", "offset": 0, ...}]

Fields

Field	Type	Description
ext	string	Canonical extension, lowercase, no dot.
name	string	Short display name.
fullName	string	Full, expanded format name.
mimeTypes	string[]	One or more registered MIME types.
signatures	object[]	Magic-byte signatures with hex, offset and note.
openWith	object	Suggested apps per operating system.
convertTo	string[]	Sensible target formats for conversion.
safety	string	Plain-language note on whether the file is safe to open.

Terms

The data is compiled from public specifications and offered under a CC BY 4.0 licence. Attribute WhatFileType when you republish it.