Blog
Practical guides that go with the tools. Short, factual and written by a person.
How to compare two texts or files and read a unified diff
Paste two texts or open two files to see what changed, ignore whitespace or case, and learn to read a unified diff, line by line, with a worked example.
How to compress images without losing quality (and what EXIF data you share)
What actually makes an image file big, which format and quality to choose, and what a photo quietly tells people about where and when you took it.
Convert CSV to JSON without breaking quotes or zeros
How to convert CSV to JSON and back without losing leading zeros, long numbers, quoted commas or accents, and why spreadsheets quietly damage the data.
EAN-13, UPC-A and Code 128: how the check digit works
Which barcode type to use, how the EAN-13 and UPC-A check digit is calculated step by step, and how Code 128 checks itself, with worked examples.
JPG vs PNG vs WebP: which to use and how to convert
When to pick JPG, PNG or WebP, why renaming a file does not convert it, and how to convert between them in your browser without uploading.
Merge PDF files without uploading them anywhere
Why most online PDF tools send your files to a server, how a browser can merge, split and rotate PDFs on your own device instead, and how to check that nothing leaves it.
Turn photos and scans into one PDF: order, size, margins
How to combine phone photos or scans into a single PDF in your browser, with the right page order, A4 or Letter size, margins and file size.
How to remove accents from text in Word, Excel and Google Sheets
Practical ways to strip accents and diacritics from names and text in Word, Excel and Google Sheets, what each method cannot do, and when it is safe to remove them.
How to remove GPS location from photos before sharing
What location data a photo carries, how to see it, and how to strip it from one photo or fifty in your browser, without uploading anything.
How to split a PDF into pages or ranges, without uploading
Split a PDF into single pages, page ranges or equal chunks in your browser. How the range syntax works, what is lost, and how to stay under a size limit.
Static vs dynamic QR codes: why a static QR code never expires
A plain explanation of what a QR code really stores, how static and dynamic codes differ, and why a static code keeps working forever.
How to verify a download with SHA-256 (and why not MD5)
Check a download against its published SHA-256 with sha256sum, shasum, Get-FileHash or your browser, and why MD5 and SHA-1 are not for security.
WCAG contrast ratio explained: AA, AAA and large text
What the 4.5:1 and 3:1 contrast ratios mean, how WCAG calculates them with a worked example, and how to check and fix a colour pair in your browser.
What makes a strong password: length, symbols, passphrases
Why length beats symbols, how to measure password strength in bits, when a passphrase is better, and why a browser-generated password is safe to use.