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The MIME Type Lookup utility provides bidirectional lookup between file extensions and MIME types. You can quickly find the correct MIME type for a file extension or discover which extensions use a specific MIME type.

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Features

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Quick lookup

Instantly convert between file extensions and MIME types:
  • Enter a file extension (e.g., .jpg, .pdf) to get the MIME type
  • Enter a MIME type (e.g., image/jpeg, application/pdf) to get the extension
  • Results include the description for context
The lookup works with or without the leading dot for extensions.
Press Enter after typing in the lookup field to instantly get results without clicking the button.

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Browse all MIME types

Explore the complete database of MIME types:
  • View all extensions and their corresponding MIME types
  • See human-readable descriptions for each type
  • Filter by category for focused browsing
  • Search across extensions, MIME types, and descriptions

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Category filtering

Filter MIME types by category:
  • Text: Plain text, HTML, CSS, JSON, code files
  • Image: JPEG, PNG, GIF, SVG, and other image formats
  • Audio: MP3, WAV, OGG, FLAC audio formats
  • Video: MP4, AVI, WebM video formats
  • Document: PDF, Word, Excel, PowerPoint documents
  • Archive: ZIP, RAR, 7z, TAR archives
  • Font: TrueType, OpenType, WOFF fonts
  • Executable: EXE, DMG, DEB, RPM packages
The database includes over 100 common MIME types covering the most frequently used file formats in web development and applications.

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Use cases

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Setting HTTP headers

Set correct Content-Type headers when serving files: 
// Express.js example
app.get('/download/:filename', (req, res) => {
  const ext = path.extname(req.params.filename);
  // .pdf -> application/pdf
  res.setHeader('Content-Type', getMimeType(ext));
  res.sendFile(req.params.filename);
});

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File upload validation

Validate uploaded files by checking MIME types: 
const allowedTypes = [
  'image/jpeg',
  'image/png', 
  'image/gif',
  'application/pdf'
];

function validateUpload(file) {
  return allowedTypes.includes(file.mimetype);
}
Don’t rely solely on MIME type for security validation. Attackers can spoof MIME types. Always validate file contents and use additional security measures.

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Email attachments

Set correct MIME types for email attachments: 
const attachment = {
  filename: 'report.pdf',
  content: pdfBuffer,
  contentType: 'application/pdf' // From MIME type lookup
};

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API responses

Return appropriate Content-Type headers for API responses: 
// JSON response
res.setHeader('Content-Type', 'application/json');

// XML response  
res.setHeader('Content-Type', 'text/xml');

// CSV download
res.setHeader('Content-Type', 'text/csv');
Modern frameworks often set Content-Type automatically, but knowing the correct MIME type is still important for debugging and explicit configuration.

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Browser behavior

Understanding MIME types helps control browser behavior:
  • application/octet-stream: Forces download instead of display
  • text/plain: Displays as plain text
  • application/pdf: Opens in browser PDF viewer
  • image/***: Displays inline as image

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Common MIME types

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Web content

ExtensionMIME TypeUsage
.htmltext/htmlHTML pages
.csstext/cssStylesheets
.jsapplication/javascriptJavaScript
.jsonapplication/jsonJSON data
.xmltext/xmlXML documents

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Images

ExtensionMIME TypeUsage
.jpg, .jpegimage/jpegJPEG images
.pngimage/pngPNG images
.gifimage/gifGIF images
.svgimage/svg+xmlSVG vectors
.webpimage/webpWebP images
SVG files use image/svg+xml because they are XML-based vector graphics, not raster images.

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Documents

ExtensionMIME TypeUsage
.pdfapplication/pdfPDF documents
.docxapplication/vnd.openxmlformats-officedocument.wordprocessingml.documentWord documents
.xlsxapplication/vnd.openxmlformats-officedocument.spreadsheetml.sheetExcel spreadsheets
.pptxapplication/vnd.openxmlformats-officedocument.presentationml.presentationPowerPoint presentations

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Archives

ExtensionMIME TypeUsage
.zipapplication/zipZIP archives
.tarapplication/x-tarTAR archives
.gzapplication/gzipGZIP compressed
.7zapplication/x-7z-compressed7-Zip archives

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MIME type structure

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Format

MIME types follow the format: type/subtype Type (main category):
  • text: Textual content
  • image: Image content
  • audio: Audio content
  • video: Video content
  • application: Binary or mixed content
  • multipart: Multiple parts (used in email)
Subtype (specific format):
  • Identifies the exact format within the main category
  • Can include vendor prefixes (e.g., vnd.ms-excel)
  • Can include suffixes (e.g., image/svg+xml)
Vendor-specific subtypes use the vnd. prefix, while personal/experimental types use prs. or x- prefixes.

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Parameters

MIME types can include parameters: 
text/html; charset=utf-8
application/json; charset=utf-8
text/plain; charset=iso-8859-1
The charset parameter specifies the character encoding for text-based MIME types.

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Best practices

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Accurate MIME types

Always use accurate MIME types:
  • Don’t use text/plain for JSON or HTML content
  • Don’t use application/octet-stream when a specific type exists
  • Match the MIME type to the actual content format
Incorrect MIME types can cause browsers to misinterpret content, leading to security vulnerabilities (MIME sniffing attacks) or broken functionality.

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Content-Type headers

When serving files: 
// Good - specific MIME type
res.setHeader('Content-Type', 'application/json');

// Bad - generic fallback when specific type is known
res.setHeader('Content-Type', 'application/octet-stream');

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MIME type validation

Validate MIME types on both client and server: 
// Client-side (HTML5)
<input type="file" accept=".jpg,.jpeg,.png" />
<input type="file" accept="image/jpeg,image/png" />

// Server-side (Node.js)
if (!allowedMimeTypes.includes(file.mimetype)) {
  throw new Error('Invalid file type');
}
The accept attribute in HTML5 file inputs can take both MIME types and file extensions. Using MIME types is more precise.

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X-Content-Type-Options

Prevent MIME type sniffing: 
X-Content-Type-Options: nosniff
This header tells browsers to strictly follow the declared Content-Type and not try to guess the MIME type by examining the content.

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