File extension lookup

Find the media type for a filename.

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Privacy details

File extension lookup processes your input in this browser. Inputs and results are excluded from analytics. Recent tools save tool names, visit counts and last-visit times. Saved tools store only their names. Draft saving is optional and stays on this device; delete saved text with the draft controls. Loading text from a URL is optional and contacts that server; its URL and your IP address are visible to the server. An optional “Use in” action keeps a handoff in this tab. The next tool removes it on arrival and ignores it if more than a minute has passed.

Copy link includes the inputs you choose to share in the address. Anyone with that link can reopen them. Files and generated results are excluded. Password and key tools share settings only.

Your input

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Your result

Reset reloads the tool with its starting values and releases open files and device controls. Saved drafts stay on this device until you delete them.

Links include your inputs and settings. Anyone with the link can see them, so leave out private text. Files and generated results are left out; random draws run again.

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Updated 2026-09-20

File extension lookup explained

Enter one filename or extension per line to look up its registered media-type association. Uppercase and lowercase extensions match. Unknown extensions stay unknown; no file is opened or uploaded.

A worked example

picture.png maps to image/png. Changing its name does not change the bytes inside the file.

Before you use the result

Uses the bundled mrmime mapping. Extensions can be misleading, and several formats share containers or extensions. This is not a malware, signature or file-integrity check.

Next: File checksum calculator

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ToolOctopus. “File extension lookup.” Updated 2026-09-20. https://tooloctopus.com/file-extension-lookup.

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