Why does one extension map to several MIME types?

Formats accumulate aliases over time (.mp3 maps to audio/mpeg while older stacks expect audio/mp3). Servers expect the canonical one; this tool shows the common mappings so you can pick what your stack accepts.

What happens if I send the wrong Content-Type?

Browsers may refuse to execute scripts (strict MIME checking), render text as plain text, or trigger a download. API clients also pick their parser from the Content-Type, so wrong types cause silent parse failures.

What is the difference between text/plain and application/octet-stream?

text/plain tells the client the bytes are human-readable text; octet-stream means "opaque binary, save it". Sending octet-stream for something renderable is the classic cause of forced downloads.

MIME types — Guide

Convert MIME types to file extensions and vice-versa.

What it is and when to use it

Look up which MIME type matches a file extension and vice versa. Searchable in both directions, so you can resolve "what Content-Type do I send for .woff2" as easily as "which files does audio/mpeg cover". The mapping matters every time you configure a web server, write an upload handler or debug a file that downloads instead of rendering.

Looks up MIME types and file extensions from one another — useful when configuring a server or writing upload validation.

How to use it

Enter a MIME type or an extension
Read the corresponding form
Copy and use it

Things that trip people up

The mapping is the curated mime-types dataset, not the full IANA registry — brand-new or proprietary types may be missing, so confirm official types against the IANA Media Types registry
Rows stay hidden until you type a query or turn on "show all": the full table is hundreds of entries, so the default view is empty by design

Questions people ask

Why does one extension map to several MIME types?: Formats accumulate aliases over time (.mp3 maps to audio/mpeg while older stacks expect audio/mp3). Servers expect the canonical one; this tool shows the common mappings so you can pick what your stack accepts.
What happens if I send the wrong Content-Type?: Browsers may refuse to execute scripts (strict MIME checking), render text as plain text, or trigger a download. API clients also pick their parser from the Content-Type, so wrong types cause silent parse failures.
What is the difference between text/plain and application/octet-stream?: text/plain tells the client the bytes are human-readable text; octet-stream means "opaque binary, save it". Sending octet-stream for something renderable is the classic cause of forced downloads.

Next steps

Open the MIME types tool

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