Guides
Short, practical write-ups that explain how things work, with examples you can check.
How to make a PDF smaller, tested on real files
Why PDFs get heavy and which fixes really shrink them. We measured each method on the same files, including two popular tricks that make PDFs bigger.
ImagesIs WebP really smaller than JPG? A side-by-side test
We converted the same sample photos to JPG and WebP at the same quality setting and compared file sizes. Here are the numbers, and when WebP is worth it.
ImagesJPG, PNG or WebP: which format to use, and when
A plain-language guide to choosing between JPG, PNG and WebP for photos, screenshots, logos and transparent images, with the trade-offs explained.
PDFThe fastest way to turn phone photos into a PDF for paperwork
The quickest way to turn phone photos of documents into a single, tidy PDF on iPhone or Android: how to shoot, order, shrink and check the file before you send it.
PDFHow to put a job application into one tidy PDF
Put your cover letter, CV, certificates and portfolio into one PDF in the right order, with a clear file name and a size that uploads. A step-by-step checklist.
PDFHow to pull out only the pages you need from a PDF
Pull a few pages out of a long PDF and send just those: how to write page ranges, the mistakes people make most often, and what happens to links and signatures.
PrivacyPhoto location data (EXIF): why and how to remove it before you share
Phone photos can carry the exact GPS spot where they were taken. How to check a photo for location data, when it gets shared, and how to remove it.
QR codesHow big should a printed QR code be?
How to choose the printed size of a QR code from scanning distance and link length, with module sizes worked out for 2, 3 and 5 cm codes and print-ready settings.
QR codesMake a Wi-Fi QR code so guests can connect in one scan
Create a QR code that connects phones to your Wi-Fi in one scan: what goes inside it, which phones support it, and how to share it safely with guests.
Time zonesHow to schedule meetings across daylight saving time without mistakes
Why international meetings shift by an hour in March and autumn, the exact 2026–2027 clock-change dates for the US, Europe and Australia, and how to avoid the trap.
DatesHow exact age is calculated, including 29 February birthdays
How to work out someone’s exact age in years, months and days, why the day before a birthday is the tricky case, and what happens to people born on 29 February.
MathsFour percentage mistakes almost everyone makes
Percentage change, stacked discounts, working back to the original price and percentage points: four calculations that trip people up, explained with worked examples.
TypingHow typing speed is measured, and how to test yours fairly
What words per minute really counts, why accuracy matters more than raw speed, how Korean and Japanese typing speed is measured differently, and how to test fairly.
SecurityHow long should a password be? The maths behind the advice
How length and character types change the number of possible passwords, how long each would survive a fast offline attack, and what length to choose today.
DevelopersHow to read JSON errors, and fix the seven most common ones
Trailing commas, single quotes, comments, missing brackets and more: the seven JSON syntax errors we see most often, what the error means and how to fix each one.
TextHow to find every change between two versions of a contract
Spot every edit between two drafts of a contract, lease or policy: how to get clean text out of Word and PDF, compare it line by line, and avoid missing changes.
DesignColour contrast: how much does text need to be readable?
What a contrast ratio like 4.5:1 means, the WCAG thresholds for normal text, large text and buttons, and real colour pairs that pass or fail, with the numbers worked out.
ImagesResizing vs compressing an image: what’s the difference?
Resizing changes the pixel dimensions, compressing changes how the pixels are stored. We tried both on the same photos to show when to use each, and when to use both.
NetworkingHow to find your router’s login address and sign in
How to find your router’s admin address on Windows, Mac, iPhone and Android, the usual default addresses by brand, and what to do if the page won’t open.
PrivacyIs it safe to put files into online tools? How no-upload tools work
What happens to your file when you use an online PDF or image tool, how tools that work without uploading differ, and how to check for yourself in two minutes.