MIME Type Lookup
Look up a file extension or MIME type — with the standard value plus any legacy/nonstandard alternates actually seen in the wild, an explicit note where a widely-used server's default config disagrees with the current spec (like nginx still serving .js as application/javascript), and a fallback explanation for extensions that aren't registered at all.
How it works
- Search by extension (.js) or MIME type (text/javascript) — matches update instantly
- Alternate or legacy values are shown alongside the standard one where they genuinely exist
- An unmatched search explains the application/octet-stream fallback convention
Frequently asked questions
What's the correct MIME type for .js — application/javascript or text/javascript?
text/javascript is the current standard per RFC 9239 and the HTML spec. However, nginx's default mime.types file still serves .js as application/javascript, so you'll genuinely encounter both in practice.
Why does one extension show multiple MIME types?
Some extensions have a standard (canonical) value plus a legacy or nonstandard value that's still commonly seen — like .mp3 (audio/mpeg is standard, audio/mp3 shows up too) or .jpg (image/jpeg is standard, image/pjpeg was a legacy progressive-JPEG value).
What happens with an extension that isn't in the list?
Unregistered extensions conventionally fall back to application/octet-stream — generic binary data, which typically triggers a download instead of inline display.
Can I search by MIME type instead of extension?
Yes — search works in both directions.
Related tools
From the blog
Update history
- 2026-08-30 Added: a cover image (document/image/audio/video file icons each linked to a tag by a two-way arrow, one file linked to two tags to suggest an extension with more than one MIME type, with a magnifying glass over the connections) — used as the card thumbnail, social share image, and blog title image.
- 2026-08-30 Launched: live MIME type lookup (no button) — bidirectional extension/MIME search, standard values alongside genuine legacy/nonstandard alternates, an explicit note on nginx's outdated .js default, and an application/octet-stream fallback explanation for unmatched extensions. Entirely client-side.