Checker Mime Types Extension

Fast, accurate and free online checker mime types extension tool running directly in your browser.

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1

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2

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3

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Checking MIME Types and File Extensions - A Complete Guide for Developers

Early operating systems and computer programs recognized file formats solely by their extensions (such as.txt, .jpgor.exe). However, in the era of the Internet, sending data via HTTP and e-mail, a more universal and platform-independent standard was needed. This is how theMIME Types(Multipurpose Internet Mail Extensions) system was born, now known in web standards asMedia Types. The MIME type determines the format and structure of the transferred data, telling the web browser how to process the file - whether to display it as an HTML page, run it as JavaScript, play it as a video, or download it to disk. Our free online MIME type finder is a handy tool for webmasters and developers to instantly check the MIME type of a selected file extension and vice versa.

Thanks to this, you will correctly configure the server headers (e.g. Nginx, Apache), avoid problems with downloading resources on the website and safely handle file uploads in applications.

MIME type structure and most common formats

The MIME type is written in a two-part format:type/subtype. The main type indicates a general category of data, while a subtype indicates a specific format. The table below shows the most common MIME types used in web technologies:

File extension	MIME type (Content-Type)	Main category	Description and purpose of the format
`.html / .htm`	`text/html`	text	Website document structure.
`.css`	`text/css`	text	Cascading style sheets that define the appearance of pages.
`.js / .mjs`	`text/javascript`	text	Scripts and executable code on the browser side.
`.json`	`application/json`	application	Lightweight data exchange format (API, configurations).
`.png`	`image/png`	image	A raster graphics format with lossless compression and transparency.
`.jpg / .jpeg`	`image/jpeg`	image	Lossy compression format for photographic images.
`.webp`	`image/webp`	image	A modern, highly optimized Google image format for the web.
`.pdf`	`application/pdf`	application	Adobe Acrobat Portable Documents.
`.zip`	`application/zip`	application	Compressed ZIP archive files.

How do browsers and servers use MIME types?

When transferring files over the Internet, the MIME type is passed in the HTTP response header as theContent-Typeparameter. Here's how the process works:

Client request:The browser sends a request to the server for a file (e.g. imagelogo.png).
Server response:The server reads the file from disk, determines its MIME type and sends the file with the header:
```
HTTP/1.1 200 OK
Content-Type: image/png
Content-Length: 12450
```
Browser interpretation:The browser reads the headerContent-Typeand knows that it must render the data as a PNG image rather than display it as text.

If the server sends a file with an incorrect header (e.g. sends a CSS file astext/plain), modern browsers with the protection mechanism enabled (headerX-Content-Type-Options: nosniff) will block the loading of styles, which will spoil the appearance of the page.

Frequently asked questions (FAQ)

What does the "application/octet-stream" MIME type mean?

Typeapplication/octet-streamis the default MIME type for unknown binaries. What it means to the browser is: "This is a raw byte stream of unknown format." As a result, browsers do not attempt to render such a file directly on the screen, but automatically download it to the user's hard drive.

How to associate file extension with MIME type in Nginx server?

In the Nginx server, these bindings are defined in a filemime.types, which is included in the main configuration with the commandinclude mime.types;. This file contains mappings, e.g.text/html html htm;. If Nginx serves a new file type (e.g. WOFF2 fonts), you need to make sure this file contains the entry:font/woff2 woff2;.

Are MIME types important when uploading files in PHP/Node.js?

Yes, MIME type verification is a key security element when users upload files to the server. You should never rely solely on the file extension (the user can rename the filemalicious_script.phponphoto.jpg). For verification, you should use libraries that read the so-called file signature (Magic Bytes) directly from its header (e.g. extensionfileinfoin PHP).

What is the difference between MIME and RFC?

MIME type standards are formally recorded and described in Request for Comments (RFC) documents published by the IETF. The register of official media types is maintained by IANA (Internet Assigned Numbers Authority). Any new global file format must undergo a certification process with IANA to receive an official MIME type.

What does the "x-" prefix mean in some MIME types?

Prefixx-in a subtype (e.g.application/x-tarorimage/x-icon) indicates custom types, experimental types, or legacy formats that have not yet been officially registered with IANA. Many of them become standard and prefix over timex-is removed or retained for backwards compatibility reasons.