Check your document file format online instantly. Identify PDF, DOCX, XLSX, PPTX, RTF, TXT, and more using our secure, browser-based Document File Format Checker — fast, private, and accurate.
Document File Format Checker
Drop or choose a document to detect extension, MIME type, magic bytes, and likely format (PDF, DOCX, DOC, ODT, RTF, TXT, XLSX, PPTX, EPUB).
(text preview will appear here for TXT/RTF/PDF first pages)
You can check any file format here: File Format Checker
How to Check Document File Format
Checking your document file format online is simple and quick.
Follow these easy steps:
1. Upload your document.
Drag and drop or browse to select your file (PDF, DOCX, XLSX, PPTX, TXT, etc.).
2. Click “Check.”
The tool will instantly analyze the file and display:
Filename
Extension (e.g., .pdf, .docx)
MIME type
File signature (internal structure)
Detected format
3. Review the results.
You’ll know exactly what kind of file it is and whether it matches its extension.
Why Use a Document File Format Checker
Knowing your document’s actual format is essential, especially when working across different systems and devices.
Benefits include:
- Avoid compatibility issues — Some files won’t open properly unless the format is correct.
- Enhance security — Detect potentially harmful files disguised as safe formats.
- Ensure accuracy — Confirm if a file labeled “.docx” is genuinely a Word document.
- Save time — No need to download or install software; analysis happens instantly.
- Cross-format validation — Identify PDFs, text documents, spreadsheets, eBooks, and more.
This is especially helpful for professionals who handle files daily — editors, students, corporate teams, and IT specialists.
How to Check Document File Format on iPhone or Android
You can also check document file formats directly on your iPhone or Android device — no app required.
Here’s how:
- Open your mobile browser (Safari, Chrome, or Edge).
- Go to the Document File Format Checker tool online.
- Tap to upload your file (from iCloud Drive, Google Drive, or local storage).
- Click “Check.”
The tool will instantly show your file’s type, MIME, and internal signature.
This method works perfectly for PDFs, Word files, and spreadsheets without needing to open them in an app.
Offline Alternative Methods
If you want to check the file type without uploading or using a browser tool, here are device-based methods:
On Windows:
- Right-click the file → Properties → General tab → Type of file.
On macOS:
- Control-click the file → Get Info → Kind.
On Android:
- Long press the file → Details or Properties.
On iPhone:
- Use the Files app → Tap file → Info (ⓘ) to view details like file type and size.
However, these methods only show the extension, not the real format signature. That’s where the Document File Format Checker stands out — it digs deeper into the actual data structure.
Security & Privacy
Your privacy is fully protected.
The Document File Format Checker runs entirely in your browser. No files are uploaded or stored online. This ensures complete confidentiality for sensitive documents such as legal contracts, resumes, financial reports, or academic papers.
You can safely analyze PDF, DOCX, and XLSX files without worrying about data leaks.
FAQs
1. How can I check what format a document is in?
Upload your document to the online Document File Format Checker, and it will instantly show the extension, MIME type, and detected format.
2. How do I check the file type of a PDF?
A valid PDF starts with the signature “%PDF” in its header. The checker tool identifies this automatically.
3. Can I check file formats on my phone?
Yes. The tool works seamlessly on both Android and iPhone browsers.
4. How do I know if a DOCX file is really a Word document?
The checker verifies DOCX files by detecting the “PK” ZIP signature and internal structure specific to Microsoft Word.
5. Is it safe to use an online format checker?
Yes — as long as it runs locally in your browser and doesn’t upload files, your privacy is completely secure.
Conclusion
Checking your document file format online helps ensure your files are genuine, readable, and safe to share. The Document File Format Checker offers instant detection for common formats like PDF, DOCX, PPTX, XLSX, TXT, RTF, and more — all from your web browser.
It’s fast, accurate, and secure, giving you peace of mind that your documents are exactly what they claim to be.
Whether you’re on desktop, Android, or iPhone, this tool makes file verification effortless and reliable.