MIME types & file extensions

Nearby workflows on Toolcore

• HTTP headers — when Content-Type sits beside cache or CORS headers.
• Data URL — when inlining small assets with a correct MIME prefix.
• Image convert — when output format should match the declared media type.
• HTTP fetch — to read the Content-Type a live response actually returns.

Common use cases

• Pick a Content-Type for static hosting or CDN rules before uploading assets.
• Decode a browser file input’s empty type field by cross-checking the extension here.
• Pair with the Data URL tool when building inline data: URLs with a correct MIME prefix.

Common mistakes to avoid

• Treating this table as the only valid mapping

  Servers and operating systems may use application/octet-stream or text/plain for unknown files; APIs sometimes deviate from common conventions.

• Confusing charset parameters with the MIME type

  Headers often look like text/html; charset=utf-8—the charset is a parameter on the same type, not a separate MIME.

• Assuming file extension always equals Content-Type

  Trust response headers and magic bytes for security; extensions are hints only.

FAQ