Guides
The questions that come before the tool. Which format, what size, how to get under a limit — answered properly, then pointed at something that does the job.
Choosing an image format
A straight answer for each kind of image — photographs, logos, screenshots, transparency — and what each format costs you.
7 minSocial media image sizes
Current upload dimensions for Instagram, X, LinkedIn, Facebook, YouTube, TikTok and Pinterest — plus how to crop without losing the subject.
6 minMaking a file smaller
What actually makes a PDF or an image large, which lever to pull first, and how to lose the least quality doing it.
6 minAre online tools safe?
Most converters upload your file to a server you know nothing about. Some do not need to — here is how to tell the difference, and how to check for yourself.
7 minHashing, encoding and encryption
Base64 is not encryption, a hash is not reversible, and confusing them is how credentials end up in plain sight. What each one is actually for.
8 minWorking with PDFs
Why the text will not copy, why the file is 40MB, why editing one is awkward — and what to do about each.
6 minColour on the web
Four ways to write the same colour, and why the newest one finally makes lightness mean what you expect.
6 minMetric and imperial
Why two systems still exist, the conversions worth memorising, and the three that catch people out — including a gallon that is not a gallon.
7 minMeasuring a room
Which measurements each job actually needs, how much to add for waste, and the openings people forget to subtract.
7 minRegular expressions
The dozen or so pieces that cover almost every real use, why greedy matching surprises everyone, and when not to reach for a regex at all.
9 min