The file uploads but the type is wrong

A server rejects your file because the Content-Type header says application/octet-stream when it should say image/webp. Getting the MIME type right is what lets browsers render, download, or preview correctly.

Look it up both ways

The MIME Type Lookup maps a file extension to its MIME type and back. Type .webp to get its type, or paste application/json to see which extensions carry it. No guessing, no digging through a reference table.

Pair it with URL handling

When the file travels in a URL, the URL Parser helps you confirm the path and extension are what you expect before the request goes out. Set the right type, then verify the link that carries the file.

Where it matters

Setting the correct header for an API file upload.
Serving a static file with the right content type.
Debugging why a browser downloads instead of displays.

Frequently Asked Questions

Why does my file download instead of opening?

Because the response carried a content type that tells the browser to treat it as an attachment, or a type the browser does not know how to render. The fix is the header the server sends, not the file itself.

Does the extension alone always decide the type?

It is the usual signal, which is why a lookup table is useful, but a server can send any type it likes and a client can sniff content. Treat the extension as the expectation the server should be meeting.

Why are there two types for the same thing?

Older types predate the modern ones and survive for compatibility, so a single format may have a legacy name and a current one. Sending the modern type is correct, and knowing both helps when you read old configuration.

Look up MIME types by file extension