MIME Type Checker

The MIME Type Checker is a client-side reference tool that performs bidirectional lookups between file extensions and MIME types. Enter a file extension (e.g., .pdf, .json, .woff2) and the tool returns the corresponding MIME type. Enter a MIME type (e.g., application/json, image/png) and the tool returns the matching file extension. The tool contains a built-in lookup table covering 35+ common web MIME types across categories: text (html, css, js, json, csv, markdown), image (png, jpg, gif, svg, webp, ico), video (mp4, webm), audio (mp3, wav), font (woff, woff2, ttf, otf), application (pdf, zip, gzip, wasm, xml), and Microsoft Office formats (doc, docx, xls, xlsx). This is essential for configuring Content-Type headers in servers, defining Accept headers in API requests, and setting up file upload handling in web applications.

MIME types are required for correct HTTP Content-Type headers, but their exact strings are difficult to remember — is it text/javascript or application/javascript? Is it application/x-protobuf or application/protobuf? The MIME Type Checker provides instant, reliable lookups that eliminate guessing and prevent the subtle bugs caused by incorrect MIME types (browsers refusing to execute scripts, fonts failing to load, or API responses being misinterpreted).

This tool runs entirely in your browser — no data ever leaves your device. There is no server round-trip, no upload, no logging, and no account required. Your input is processed locally using client-side JavaScript and is never stored, transmitted, or accessible to anyone else. When you close the tab, everything disappears.

Why is text/javascript sometimes application/javascript?

<p>The MIME type for JavaScript has evolved: early browsers used text/javascript, while the IANA standard was application/javascript. Modern browsers accept both, but the recommendation varies by context (HTML script tags vs API responses).</p>

Does it include all possible MIME types?

<p>No. The tool covers the most common web MIME types. For a comprehensive list, refer to IANA's MIME media types registry at iana.org/assignments/media-types.</p>

Can I look up MIME types for font files?

<p>Yes. The tool includes font/woff, font/woff2, font/ttf, and font/otf. These are essential for configuring correct Content-Type headers for web font files.</p>

Why is the correct MIME type important?

<p>Browsers use MIME types to decide how to handle content. Wrong types cause security blocks (scripts not executing), rendering failures (fonts not loading), and download instead of display behavior. Servers must send accurate Content-Type headers.</p>

What about charset parameters?

<p>The tool returns the base MIME type without parameters. For text types, you would append ;charset=utf-8 as needed. The base type is what matters for Content-Type header configuration.</p>

Does it cover all font formats?

<p>The tool includes woff, woff2, ttf, and otf. For less common formats like eot or svg fonts, check the IANA registry directly.</p>

What MIME type should I use for Wasm files?

<p>Use application/wasm for WebAssembly files. This is the official IANA-registered type and ensures browsers execute the module correctly rather than downloading it as a binary blob.</p>

What is the difference between image/jpeg and image/jpg?

<p>The official MIME type is image/jpeg (with the three-letter extension .jpg being a DOS-era abbreviation). Both work in practice, but image/jpeg is the standard.</p>