📁 MIME Type Lookup
Runs entirely in your browser - no data sent to server
Output appears here...
📊 Key Data Points
application/wasm
Required for WebAssembly streaming compilation — wrong MIME type forces buffered mode
application/json
Correct MIME type for JSON APIs — not text/json which is non-standard
IANA registry
MIME types sourced from the IANA media type registry — the authoritative source
MIME Type Lookup — File Extension to Content-Type -- Complete USA Guide 2026
MIME types (Content-Type values) tell browsers and API clients what format a response contains. Using the wrong MIME type causes browsers to display downloads instead of rendering pages, API clients to fail parsing, and WebAssembly to disable streaming compilation.
This lookup covers 900+ file extensions with their correct MIME types, usage notes, and HTTP header syntax. Runs in your browser with instant search.
**Long-tail searches answered here:** what is the MIME type for .wasm files, correct Content-Type for JSON API response, MIME type for MP4 video HTTP header.
Pair with HTTP Headers Analyzer to check your server actual Content-Type output.
🔬 How This Calculator Works
The lookup database maps file extensions to their IANA-registered MIME types. Each entry includes: the primary MIME type, any common alternatives, whether the type requires a charset parameter (text/* types should include ; charset=utf-8), and whether the browser renders it inline or downloads it.
The search works both directions: enter a file extension (.mp4) to get the MIME type, or enter a MIME type (video/mp4) to see which extensions use it.
✅ What You Can Calculate
900+ extensions covered
Covers common and obscure formats: video, audio, documents, code, data, and specialized formats like WebAssembly and HLS manifests.
Bidirectional search
Search by file extension to get the MIME type, or search by MIME type to see which extensions use it. Useful when an API returns a Content-Type you do not recognize.
Charset requirement flags
Text MIME types should include ; charset=utf-8. Missing charset causes encoding issues in some browsers. This lookup flags which types require it.
Server config snippets
Shows the Nginx and Apache config syntax to set the MIME type — types { application/wasm wasm; } for Nginx, AddType for Apache.
🎯 Real Scenarios & Use Cases
WebAssembly streaming compilation
WebAssembly.instantiateStreaming requires application/wasm Content-Type. Using application/octet-stream falls back to buffered compilation which is significantly slower.
Video streaming setup
Setting up HLS streaming requires .m3u8 as application/x-mpegURL and .ts segments as video/MP2T. Wrong MIME types prevent Safari and iOS from loading HLS streams.
Font serving
WOFF2 fonts must be served as font/woff2. Some old servers serve them as application/octet-stream, causing font loading failures in strict browsers.
htaccess configuration
After looking up the correct MIME type, use htaccess Generator to add the AddType directive to your Apache config.
💡 Pro Tips for Accurate Results
application/json, never text/json. text/json is non-standard and not in the IANA registry. Always use application/json; charset=utf-8 for JSON API responses.
X-Content-Type-Options: nosniff everywhere. Browsers will MIME-sniff responses that lack Content-Type headers. Set X-Content-Type-Options: nosniff on every response.
WebAssembly needs application/wasm. This is the single most important non-obvious MIME type for modern web apps. Without it, WebAssembly.instantiateStreaming fails.
charset only for text types. Adding ; charset=utf-8 to application/json is technically valid but unusual — required for text/html and text/css.
🔗 Use These Together
🏁 Bottom Line
MIME types are invisible when correct and infuriating when wrong. A missing application/wasm Content-Type degrades WebAssembly performance. A wrong font MIME type silently falls back to a system font.
For server configuration: look up MIME types here, generate Apache rules with htaccess Generator, and verify output with HTTP Headers Analyzer.
What is a MIME type and where is it used?
MIME (Multipurpose Internet Mail Extensions) types identify file or data stream formats: text/html, application/json, image/png, video/mp4. They appear in: HTTP Content-Type headers (server tells browser what format the response is), Accept headers (browser tells server what it can handle), HTML type attributes, and email attachment headers. Using the wrong Content-Type causes browsers to mishandle content — a text/plain JSON response is displayed as text rather than parsed as JSON.
What MIME type should I use for JSON API responses?
application/json is correct. Content-Type: application/json; charset=UTF-8. Avoid: text/json (non-standard), text/plain (incorrect — displays raw in browser). For JSON:API spec: application/vnd.api+json. For GeoJSON: application/geo+json. For JSON-LD: application/ld+json. The application/ type indicates structured binary/non-human data; text/ indicates human-readable content.
What is application/octet-stream and when do I use it?
application/octet-stream is the generic binary type — use when you do not know the specific format, or when forcing a download. When a browser receives application/octet-stream, it prompts for download rather than displaying inline. Set Content-Disposition: attachment; filename='file.ext' alongside it to provide a filename. Specific types allow inline display: image/png shows inline, application/pdf opens in PDF viewer. Use octet-stream for generic file download endpoints.
What MIME type does WebAssembly (.wasm) use?
WebAssembly uses application/wasm. This matters: browsers require application/wasm to enable streaming compilation (WebAssembly.instantiateStreaming), which is significantly faster than buffered compilation from application/octet-stream. Configure in Nginx: types { application/wasm wasm; }. In Apache .htaccess: AddType application/wasm .wasm. Without the correct MIME type, WebAssembly loads and compiles but more slowly.
Should I trust the MIME type for file upload security validation?
Never trust MIME type alone. The browser sends the type it detects from the file extension — a malicious user can rename a PHP script to image.png and the browser sends image/png. Server-side: check file extension AND verify actual file format by reading magic bytes (first bytes unique to each format). Python: python-magic library. Node.js: file-type package. For image uploads: always re-process through an image library (Sharp, Pillow) which rejects invalid images automatically.
What MIME types do video and audio formats use?
Video: video/mp4 (.mp4), video/webm (.webm), video/ogg (.ogv), video/quicktime (.mov). Audio: audio/mpeg (.mp3), audio/ogg (.ogg), audio/wav (.wav), audio/aac (.aac), audio/flac (.flac). Streaming: application/x-mpegURL (.m3u8 HLS playlists), application/dash+xml (.mpd DASH manifests). For media source extensions, the codec string matters: video/mp4; codecs='avc1.42E01E, mp4a.40.2' specifies H.264 video and AAC audio.
What other HTTP tools are on this site?
The HTTP Headers Analyzer decodes Content-Type and Accept headers in HTTP responses. The .htaccess Generator creates Apache AddType directives for correct MIME type serving. The HTTP Status Codes reference covers 415 Unsupported Media Type. The curl Builder generates requests with specific Content-Type headers. All are in the Dev Tools section.