Guides
Short explainers about the file formats and workflows that bring people here. They're written for the person who already half-knows what's going on and wants a straight answer, not a thousand-word preamble about how "in today's digital world" files exist.
Each one is independent. Read whichever matches the problem you're staring at. The converters on this site are mentioned where they're relevant, but every guide is meant to stand on its own — you can leave with what you came for and never touch the tools.
What is an EPUB?
The zipped XHTML container behind every modern ebook, and what changes between EPUB 2, 3, and 3.2.
HEIC explained
Why iPhone photos won't open on Windows, and the licensing reason it stayed that way for years.
How OCR actually works
Binarization, deskew, line detection, and the LSTM that finally made Tesseract usable.
JPG vs PNG vs WEBP vs HEIC
What each format compresses well, real file-size numbers, and a decision tree for picking one.
Sideload ebooks to your e-reader
Step-by-step for Kindle, Kobo, Boox, and reMarkable, including the Scribe.
Why convert in your browser
The privacy case for not uploading files to a stranger's server, and how WebAssembly made it possible.