Every PDF problem, solved.
Clear, step-by-step answers for compressing, converting, unlocking and fixing PDF files — plus the basics of how PDFs actually work.
Popular PDF problems
The questions people ask most.
Can't Copy Text From a PDF? Here's Why and How to Fix It
Fix PDFs where text won't select, copies as gibberish, or copying is blocked by permissions.
How to Compress a PDF (Free, Any Device)
Make a PDF smaller for free on Windows, Mac, iPhone, Android or online — without ruining quality.
How to Convert a PDF to Word (Free)
Turn a PDF into an editable Word document for free using Word, Google Docs or online converters, and keep the layout intact.
How to Edit a PDF for Free
Change text, add notes, insert images or fix typos in a PDF using free tools on Windows, Mac and phones.
How to Merge PDF Files Into One
Combine multiple PDFs into a single file for free on Windows, Mac, iPhone, Android or online.
How to Remove a Password From a PDF
Unlock a PDF you have the password for, remove printing or copying restrictions, and what to do if you forgot the password.
How to Scan a Document to PDF With Your Phone
Use your iPhone or Android phone as a free document scanner that creates clean, cropped PDFs.
How to Sign a PDF (Free, No Printing)
Add your signature to a PDF on Mac, Windows, iPhone or Android — without printing and scanning.
PDF Won't Open? How to Fix It
Troubleshoot PDFs that won't open, show errors like 'file is damaged', open blank, or ask for a program.
PDF basics
Understand the format, and most problems make sense.
- 1. What Is a PDF File?What PDF stands for, why it was invented, and why a PDF looks the same on every device.
- 2. PDF Versions and PDF/A ExplainedPDF 1.4, 1.7, 2.0, PDF/A, PDF/X, PDF/UA — what the versions and sub-standards mean and when they matter.
- 3. Scanned PDF vs Text PDF: What's the Difference?Why some PDFs let you select and search text while others don't — and how to tell which kind you have.
- 4. Fonts in PDF Files: Embedding and SubsettingHow PDFs store fonts, what 'embedded' and 'subset' mean, and why missing fonts cause garbled or substituted text.
- 5. Vector vs Raster: How Images Work in PDFsWhy some PDF graphics stay sharp at any zoom while others get blurry, and how image resolution drives file size.
- 6. What Is OCR and How Does It Work With PDFs?OCR (optical character recognition) turns pictures of text into real, searchable text. Here's how it works and where to get it free.
Answer first
Every guide starts with the short answer. Details follow if you need them.
Works on any device
Steps for Windows, Mac, iPhone, Android and the browser.
Privacy-minded
We point out when a method keeps your files on your own device.