How to Look Up a MIME Type by File Extension
To look up a MIME type by file extension, type the extension (for example png or mp4) into the ByteTools MIME Type Lookup and read the matching content type from the filtered table — image/png, video/mp4, and so on. The same box works in reverse: paste part of a content type like application/ and it lists every extension that uses it. Everything is searched locally in your browser, so answers appear the instant you type.
Setting the right Content-Type header is one of those small details that quietly breaks things when it is wrong — files download instead of previewing, fonts fail to load, and APIs reject valid payloads. This guide walks through using the lookup so you always paste the correct value into your server or code.
What the MIME Type Lookup does
A MIME type (also called a media type or content type) is a short label such as text/html or application/json that tells browsers and servers what kind of data a file holds. The lookup ships with a comprehensive map of common formats across documents, images, audio, video, fonts, archives and web assets, each paired with its extension and a plain-language description. Because the whole map is bundled into the page, it filters as fast as you can type and keeps working with no internet connection.
Step-by-step: find a MIME type
- Open the tool and click into the search box.
- Type a file extension such as
webp,svgormp4. Leave off the dot — the tool matches either way. - Scan the filtered rows. Each shows the extension, its MIME type and a short description of the format.
- Copy the content type exactly as written into your server config or code.
To go the other direction, type part of a content type instead — for example audio/ to see every audio extension, or font/ to confirm whether a web font should be served as font/woff2.
Reading the results table
Each match gives you three pieces of information. Here is how they line up for a few common formats:
| Type it | Extension | MIME type |
|---|---|---|
| png | .png | image/png |
| json | .json | application/json |
| mp4 | .mp4 | video/mp4 |
| woff2 | .woff2 | font/woff2 |
| application/pdf |
Notice that some extensions share a type — .jpg and .jpeg both map to image/jpeg — so the tool lists each separately to confirm the exact pairing you need.
Why in-browser and private matters
The mapping is embedded in the page and searched with local code, so nothing you type is uploaded anywhere. That has two practical benefits: the results are instant with no network round trip, and the reference stays available even when you are offline or working behind a strict firewall. It behaves like a lightweight desktop reference that happens to live in a browser tab.
Try the MIME Type Lookup — free and 100% in your browser.
FAQ
Do I include the dot when searching by extension?
No — you can type png or .png and get the same result. The lookup matches the extension text either way, so use whichever is quicker.
Which MIME type should I use for a downloadable file?
If you want the browser to save a file rather than preview it, serving application/octet-stream forces a download. But for normal files, use the real content type from the lookup and add a Content-Disposition: attachment header if you specifically want a download prompt.
How do I set the Content-Type once I have it?
Copy the value into your server configuration (for example an Nginx types block or an Apache AddType line) or into the header you set in code, such as res.setHeader('Content-Type', 'application/json'). The lookup only tells you the correct value; where you apply it depends on your stack.
Does the tool cover newer web formats?
Yes — modern web assets such as image/webp, image/avif and font/woff2 are included alongside the classic document and media types, so you can validate current front-end pipelines.
Related free tools
- HTTP Status Code Lookup — decode response codes while you debug headers.
- URL Parser — break a URL into its parts to inspect requests.
- Image Metadata Viewer — inspect an image file's real format and EXIF data.
- ASCII Table — a quick reference for character codes.
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