About MIME Type Lookup
MIME Type Lookup answers the question in both directions: give it a file extension and it returns the media type you should send, or give it a media type and it returns the conventional extension. Both are useful, because server configuration, upload validation and file-serving rules tend to be written in one form while the thing you have in hand is in the other.
The query is forgiving about how it is written. A leading dot is stripped and case is ignored, so the same answer comes back whether the extension is typed as html or as .HTML, and a full media type such as an image type returns its usual extension for the reverse lookup.
Where an exact match is not found, the tool falls back to a partial match against both the extensions and the media types it knows, which often lands on something close enough to be useful. That fallback also reveals the boundary: this is a curated table of the types that turn up in ordinary web work, not the full registry. Obscure formats and vendor-specific types will not be present, and the honest answer in that case is to check the format specification or the registry directly.
How to use MIME Type Lookup
- 1 Type either a file extension or a full media type.
- 2 Read the matching entry returned for it.
- 3 If nothing matches exactly, read the partial matches to find the nearest type in the table.
Frequently asked questions
Does it cover every registered media type?
No. It holds a curated set of the types that appear in everyday web and API work. Niche formats and vendor-specific types are absent, and for those the authoritative registry or the format specification is the right source.
Why do some formats have more than one acceptable type?
Because competing registrations exist and brokers disagree about which is correct — the differences between the historically registered forms of some document and archive types are a well-known example. Whichever you choose, be consistent, since a mismatch between the declared type and the served bytes causes some clients to refuse the file.
Can I trust the type for upload validation?
Not on its own. The media type describes how to interpret bytes, not whether they are safe, and a client can declare any type it likes. Real upload validation inspects the content itself or converts it server-side.
What is the correct type for a JSON response?
The application form of JSON, usually with an explicit UTF-8 charset. Some browsers will still parse a wrongly typed payload, which is exactly why serving JSON as plain text survives testing and then breaks a strict client in production.
Free, online, and private
Free to use
MIME Type Lookup is completely free. There is no account to create, no login, and no hidden charge or usage limit.
Runs online in your browser
It is a free online tool that runs entirely in your browser. Nothing to download or install — open the page and start using it right away.
Your data stays private
All processing happens locally on your device. Your input is never uploaded, stored, or tracked, so it never leaves your browser.
How MIME Type Lookup behaves in detail
These are the specifics of this implementation — the exact ranges, defaults and fixed settings you are working with.
| Parameter | Value |
|---|---|
| Extension table | 32 hard-coded entries, from html and css through to woff2 and ttf |
| Reverse index | built by inverting that table, so only 30 distinct MIME strings resolve — jpeg and yml are the spellings kept |
| Query cleaning | the input is trimmed, lower-cased and stripped of one leading dot, so .PNG and png behave identically |
| Lookup stages | exact extension, then exact MIME string, then a substring scan across both the extension and the type |
| Fallback | every partial match is listed as ".ext → type" lines, or the single line "No match found" |
Compiled from the implementation of this tool and checked against it by itoolnet.
What MIME Type Lookup does not do
Knowing the edges of a tool saves more time than another list of its features. These are the cases where it will not do what you might expect.
- The table is a hand-written list of 32 extensions, so anything outside it lands on substring matching or the no-match line: .wasm, .avif, .heic, .7z, .rar, .mjs, .map and .otf are all absent from it.
- The reverse direction inherits the duplication. image/jpeg and text/yaml each have two extensions in the table and inverting keeps the last one seen, so image/jpeg answers .jpeg and text/yaml answers .yml, with no mention of .jpg or .yaml.
- The substring stage has no boundaries and no ranking. An empty query matches every entry and prints all 32 rows, an input like image prints every image type, and a full header value such as text/html; charset=utf-8 matches nothing at all.
Tested and documented by itoolnet, the team that builds and maintains this site.