MIME Type Interactive Lookup
指导
MIME Type Interactive Lookup
Look up the correct MIME type for any file extension — or find the file extensions associated with a MIME type. Built on the IANA media type registry, this interactive lookup gives you instant, accurate results with category labels and one-click copying so you can drop the right Content-Type into your code without second-guessing.
如何使用
- Type a file extension (such as
.pdf,mp4， 或者json) into the search box, or paste a MIME type likeimage/png. - The result card shows the matching MIME type(s), associated extensions, the top-level category (image, video, audio, text, application, font, model, multipart, message), and the default charset where applicable.
- Click the copy icon next to any MIME string to drop it into your clipboard.
- Use the Common Types chips below the search box to jump straight to popular file formats.
特征
- Bidirectional lookup – search by file extension or by MIME type and get the matching counterpart.
- Multiple MIME types – when an extension maps to more than one media type (for example
.jsmatches bothapplication/javascript且text/javascript), every entry is shown. - Category badges – each result is labeled with its top-level type so you can tell media, document, and font types apart at a glance.
- Charset hint – text-based types include the recommended default charset to use in
Content-Type标头。 - ——点击复制按钮，粘贴到你的 CSS 中。两秒钟搞定。 – grab the MIME string with a single click, ready to paste into HTTP headers or upload validators.
- Common types shortcut – clickable chips for the file formats developers reach for most often.
- 完全客户端 – every lookup runs in your browser; no upload, no tracking, nothing leaves the page.
何时使用此工具
- Setting the correct
Content-Typeheader for an HTTP response or file upload. - Configuring a server allow-list of acceptable upload formats.
- Writing a parser that needs to branch on the MIME category of an incoming file.
- Filling in
acceptattributes on HTML<input type="file">elements. - Debugging why a file is being served with the wrong type by checking what its extension should map to.
常问问题
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What is a MIME type?
A MIME type (Multipurpose Internet Mail Extensions type), also called a media type or Content-Type, is a standardized label that tells software what kind of data a file contains. It has two parts separated by a slash: a top-level category (image, text, application, etc.) and a subtype (png, html, json, etc.). Browsers, mail servers, and APIs use the MIME type to decide how to handle a payload — whether to render it inline, prompt a download, or refuse it.
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Why does the same extension sometimes have more than one MIME type?
Historical drift. Many media types were registered with one official identifier but became known by an unofficial alias that browsers and servers had to keep accepting for compatibility. JavaScript is the canonical example: the IANA-registered type is text/javascript, but application/javascript was widely used for years and is still considered valid in HTTP. RFC 9239 now makes text/javascript the recommended choice, but both forms continue to appear in the wild.
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Where do MIME type registrations come from?
The Internet Assigned Numbers Authority (IANA) maintains the official registry. Anyone can submit a new media type through one of three processes — standards tree (requires an RFC), vendor tree (vendor-specific, prefixed with vnd.), or personal/experimental tree (prefixed with prs. or x.). The registry is the source of truth, but in practice tools also rely on community-maintained databases like mime-db that consolidate IANA, Apache, and nginx mappings into a single dataset.
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Why should I trust extension-based detection at all?
You should not — for security-sensitive flows. File extensions are user-controlled metadata and trivially spoofed. For uploads, validate by reading the file's magic bytes (the first few bytes that identify the real format) rather than trusting the name. Extension-to-MIME lookup is the right tool for setting outbound Content-Type headers and for hinting allow-lists, but it is the wrong tool for deciding whether an uploaded file is safe to process.
