File Type Checker
Open any file to see its real type from the first bytes (magic numbers) for 60+ formats, and whether the extension matches. Nothing is uploaded.
Input
Stays in your browserShortcuts: Ctrl+Enter run · Ctrl+Shift+C copy result · / search (use ⌘ on Mac)
Next steps
Done here? Use the Send to… menu on the result to carry it on to Hex Dump.
Free Online File Type Checker
A file name can lie. This page reads the first bytes of the file, which tell what it really is, and compares the answer with the extension. It gives developers a quick browser-based way to solve a focused file type checker task before moving the result into a project.
How to use File Type Checker
Open a file, or paste its first bytes as hex or Base64. The file is read in your browser and never uploaded.
Common mistakes
- Trusting the extension: it can be changed by anyone.
- Pasting text instead of bytes: paste hex or Base64, or open the file.
Frequently asked questions
What are magic bytes?
Many file formats start with a fixed pattern of bytes. A PNG always starts with 89 50 4E 47 and a PDF with %PDF. Programs use it to know what a file really is.
Why can the extension be wrong?
Renaming a file only changes its name, not its content. A PNG renamed to .jpg is still a PNG. Mismatches can also hide dangerous files, so check files you did not make.
Why is a file called "Unknown"?
Plain text and some formats have no fixed start. The page shows the first bytes so you can look the pattern up.
Is the file uploaded?
No. Only the first bytes are read, in your browser.
How do I use this file type checker tool?
Use the interactive controls above; processing stays in your browser and the result is intended as a practical starting point for development work.
More Code & Conversion
Unix Timestamp ConverterTurn computer time into a real dateTimezone ConverterFind the time in other citiesNumber / Byte FormatterTurn bytes into KB, MB and GBCron ParserUnderstand a cron schedule in plain EnglishBase ConverterConvert binary, decimal and hex numbersCase ConverterChange text to UPPER, lower, Title caseSlug GeneratorMake clean web addresses from titlesSubnet CIDR CalculatorWork out IP ranges for networks