Guides
Practical, sourced guides to working with PDFs, images, data formats, passwords and web pages — each linked to a free tool.
- developers
Base64 and Data URLs: When to Inline Images (and When Not)
What Base64 is, why it makes data about 33% bigger, how data URLs work in HTML and CSS, and when inlining an image speeds a page up or slows it down.
- privacy
How to Check if an Online Tool Uploads Your Files
A 2-minute test with your browser’s developer tools shows whether a PDF or image tool sends your file to a server. Step by step, for Chrome, Edge, Firefox and Safari.
- design
Colour Contrast Ratios Explained: WCAG 4.5:1 and 3:1
What a contrast ratio is, which ratios WCAG 2.2 requires for text, large text and interface elements, and how to fix colours that fail without changing your brand.
- developers
Common JSON Errors and How to Fix Them
Trailing commas, single quotes, comments, NaN and unescaped line breaks: the JSON mistakes that break parsers, why they are invalid, and how to fix each one.
- images
How to Compress an Image to 100 KB, 1 MB or Any Size
Upload forms often demand images under 100 KB or 2 MB. How JPEG quality and pixel size affect file size, and the fastest way to hit a limit without ruining the photo.
- developers
How to Decode a JWT Safely: Decoding Isn’t Verifying
What is inside a JSON Web Token, how to read its header and claims, what “exp” and “iat” mean, and why pasting production tokens into random websites is a risk.
- security
How Long Should a Password Be? NIST’s 2025 Rules Explained
NIST’s 2025 guidance says length beats complexity: 15 characters for password-only logins, no forced resets, no composition rules. What it means for you.
- images
JPG vs PNG vs WebP vs AVIF: Which Image Format to Use
A practical guide to choosing image formats for photos, screenshots, logos and websites, with the trade-offs in size, quality, transparency and compatibility.
- pdf
Merge, Split and Reorder PDF Pages Without Uploading
How to combine PDFs, extract pages, delete or reorder pages and add page numbers in your browser, with tips for big files and scanned documents.
- qr codes
Static vs Dynamic QR Codes: Which Ones Never Expire
Why some “free” QR codes stop working after a trial, how to make a QR code that works forever, and how size and error correction affect scanning.
- seo
Title Tag and Meta Description Length: What Google Says
Google sets no fixed limit for titles or meta descriptions but truncates them to fit the screen. How to write both so they survive truncation and earn the click.
- developers
Unix Timestamps Explained: Seconds, Milliseconds and 2038
What a Unix timestamp is, how to tell seconds from milliseconds, time zones and leap seconds, and what the year 2038 problem means for 32-bit systems.
- privacy
What Your Photos’ EXIF Data Reveals and How to Remove It
Photos from phones can carry GPS coordinates, the device model and the exact time. What EXIF metadata is, who can see it, and how to strip it without losing quality.
- pdf
Why Your PDF Won’t Compress (and What Actually Works)
Some PDFs shrink by 90%, others by 2%. What makes a PDF large — images, fonts, scans — and how to reduce it without making text blurry.