# File Type Checker: Find a File's Real Format Free - [Home](/) - - - [Tools](/tools/) - - - File Type Checker # File Type Checker: What Is This File Really? A file's extension is just part of its name, and anyone can change it. Drop in any file to see its real format, read from the bytes inside, and get a clear warning when the name doesn't match. Drop files to check their real type Any file type, any size - only the first bytes are read Choose files Free to UseNo hidden chargesNo Software InstallationRuns in your browserNo Sign UpStart instantly ## Work privately, then store privately with DragBin Processing a file in your browser keeps it private in the moment. The files you keep and share need that same guarantee for the long run. DragBin protects files with [client side](/client-side-encryption/), [quantum resistant encryption](/post-quantum-encryption/) (ML-KEM + AES-256) keeping sensitive data private with a [zero knowledge](/zero-knowledge-encryption/) security architecture. - Get 5GB quantum resistant storage forever - Unlimited sharing, unlimited bandwidth and unlimited file size uploads - Integrated Global CDN and preview media in 4k/8k [Try DragBin Today](https://dragbin.com) ## How to Check a File's Real Type Three steps, no install and no account: Step 1 Drop, paste or choose one or more files of any type or size. Step 2 The checker reads the first bytes of each file and matches them against known format signatures. Step 3 See the detected format, its MIME type and usual extensions, and any mismatch with the file's name. ## Why Check a File's Type? Extensions are easy to fake or get wrong. Checking the contents tells you what will actually happen when you open the file, and helps when a download or attachment won't open. ### Reads the Bytes Detection uses the file's signature, not its name, so a renamed file can't hide its format. ### Spots Mismatches A .jpg that is really a web page or a program gets flagged right away. ### Any File, Many at Once Check a whole batch of files in one go, from images and documents to archives and apps. ## Private and Fast by Design The checker runs entirely in your browser. It reads only a small slice of each file, so nothing is uploaded and multi-gigabyte files are checked as quickly as small ones. ### Nothing Uploaded Files are read locally in your tab and never sent to a server. ### Header-Only Reading Only the first 64 KB (plus the end of ZIP files) is read, never the whole file. ### Honest Results It tells you what a file is. It doesn't claim to scan for malware or judge safety. ## Try DragBin Today Pair private, in-browser file tools with zero-knowledge, quantum-resistant cloud storage. 5GB free, forever. [Claim 5GB free storage (opens in new tab)](https://app.dragbin.com/signup) ## Frequently Asked Questions ### How does the file type checker work? Most formats begin with a fixed byte pattern, often called a magic number or signature. The checker reads the first 64 KB of each file (and, for ZIP-based files, the last 64 KB where the list of contents is stored) and compares those bytes against a table of known signatures. The file name plays no part in the result. ### Are my files uploaded? No. Files are read by JavaScript in your browser tab and nothing is sent to a server. Only a small slice of each file is read, so even very large files are checked in a moment. ### Does this tell me whether a file is safe or contains malware? No. It only identifies what kind of file something is. It doesn't scan for viruses or judge whether a file is harmful. If it says a file is a program or script, only open it if you trust where it came from. ### What does an extension mismatch mean? It means the file's contents don't match its name, for example a photo.jpg that is actually a web page or a Windows program. Sometimes that's harmless, such as a PNG saved with a .jpg name, but renamed programs are a common trick, so treat them with care. ### Which file types can it recognise? Around 70 formats, including JPEG, PNG, WebP, HEIC, AVIF and JPEG XL images, MP4, MOV, MKV and other video and audio containers, PDF, Word, Excel and PowerPoint (both modern and legacy), ZIP, 7z, RAR, gzip and TAR archives, EPUB, APK and JAR files, Windows, Linux and macOS programs, and text formats such as HTML, SVG, XML and JSON. Formats without a fixed signature, like CSV or source code, show up as plain text. More free tools ## Keep going with the DragBin toolbox [ ### EXIF Remover Strip location and camera metadata from photos before you share them. ](/tools/exif-remover-tool/)[ ### Image Converter Turn an image into JPG, PNG, WebP or another format in your browser. ](/tools/image-converter/)[ ### Send Large Files Share big files with end-to-end encryption once you know what they are. ](/send/) --- Canonical: https://www.dragbin.com/tools/file-type-checker