MIME Type Lookup

Introduction

The MIME Type Lookup tool maps a file extension to its corresponding MIME type (Multipurpose Internet Mail Extensions). Enter one or more extensions such as jpg, pdf, or zip, and the tool returns the standard MIME identifier for each format. A MIME type is the standard way the internet describes the content type of a file, for example image/jpeg for images and application/pdf for PDF documents.

The tool ships with a built-in mapping table that covers common formats across development, office documents, multimedia, archives, and fonts. Developers, site operators, QA engineers, and everyday users can quickly confirm the correct MIME identifier to use in HTTP requests, API development, or file uploads, avoiding rendering or download issues caused by a wrong content type.

Technical Principles

MIME (Multipurpose Internet Mail Extensions) was first defined in RFC 2045 to describe the media type of email attachments. The HTTP protocol later adopted it widely, making it the standard for identifying resource content types on the web. A MIME type consists of a main type and a subtype, such as text/html, where text is the main type and html is the subtype. Parameters like charset or boundary may also be attached.

At its core, this tool is a static extension-to-MIME mapping table. During a query, the input is normalized to lowercase with any leading dot removed, then looked up in the table. Extensions not present in the table return an "unknown" notice. This approach needs no network access and responds instantly, and the results align with the media types officially registered with IANA, covering most formats used in everyday development.

Use Cases

• HTTP API development: confirm which Content-Type response header a file type should use so browsers render it correctly
• File upload validation: check that a file's MIME type matches the whitelist expected by the backend
• Static asset configuration: set up correct mime.types rules for a web server (Nginx/Apache)
• Email development: determine the proper media type for attachments in mail-sending code
• Data crawling and analysis: identify the real type of downloaded files or scraped resources to avoid confusion
• Learning reference: quickly look up the standard MIME identifier for common file formats

Frequently Asked Questions

Q: What is the relationship between a MIME type and a file extension?

A: A file extension is the characters after the "." in a filename and roughly indicates the file type, while a MIME type is a more formal, cross-platform media type identifier. The two usually map one to one, though the same extension can have different MIME values in different contexts. This tool returns the value most commonly used on the internet, consistent with the IANA registry.

Q: Why can't my extension be found?

A: The format may be uncommon or use a non-standard extension. In that case the tool returns an "unknown" notice. You can fall back to a more generic MIME type such as application/octet-stream.

Q: Can I query multiple extensions at once?

A: Yes. Separate extensions with commas, spaces, or semicolons, and the tool will return the corresponding MIME type for each one, which is convenient for batch comparisons.

Typical Usage

Look up a single extension:

Input: pdf
Output:
MIME type for .pdf: application/pdf

Look up multiple extensions:

Input: jpg, pdf, zip
Output:
MIME type for .jpg: image/jpeg
MIME type for .pdf: application/pdf
MIME type for .zip: application/zip

Related Tools

This tool pairs with HTTP Status Checker as a web development aid: MIME types identify resource content types, while HTTP status codes indicate the outcome of a request. When building APIs or processing resources, it is often used together with ASCII Code Lookup, Base64 Encode, and Base64 Decode.