Guides
Practical guides to working with PDFs and images — what actually affects file size and quality, which format to pick, and how to get the result you wanted.
Utilities
How to check a file's checksum, and what it actually proves
What a checksum is, how to compute and compare one on Windows, Mac, and in a browser, and the difference between what it proves and what people assume.
· 4 min read
PDF · Compress
How to reduce PDF file size without losing quality
Why PDFs get large, which compression actually works for your file, and how to shrink one without turning the text to mush.
· 4 min read
Image · Convert
JPG, PNG, or WebP: which image format should you use?
A practical guide to choosing between JPG, PNG, WebP and AVIF — what each is genuinely good at, and the mistakes that bloat your files.
· 4 min read
Image · Convert
HEIC photos from your iPhone, and how to stop the problem at the source
Why your iPhone photos will not open on Windows, the iPhone setting that fixes it permanently, and how to convert the HEIC files you already have.
· 4 min read
PDF · Organize
How to combine several PDFs into one file
How to merge PDFs in your browser, on Mac, and on Windows — plus how to control page order and what to do when the result is too large.
· 3 min read
PDF
Are online PDF tools safe? What actually happens to your file
What really happens when you upload a document to a free PDF site, how to tell whether a tool uploads at all, and how to check for yourself.
· 4 min read