Practical guides, roundups, and explainers on the tools and concepts that show up in day-to-day work — all written for use alongside the free tools on the rest of the site.
QR codes are everywhere now, but most people do not know how they work or when to use them over a regular barcode. This guide covers the structure, the error correction, the right size, and the practical design rules.
WCAG contrast ratios depend on lightness, not hue. Learn the math, the AA and AAA thresholds, the “color is not the only signal” rule, and a workflow for testing every pairing before you commit to a palette.
UUID v7 is the 2024 successor to v4 for database primary keys. Learn what changed, why it exists, when to keep v4, and how to migrate without breaking anything.
Apple’s HEIC format saves storage but breaks the moment you try to share a photo. Learn what HEIC is, why it exists, how to convert it to JPG locally without uploading, and the trade-offs of every approach.
Four encodings that all turn binary into text, but with different alphabets, sizes, and URL-safety. This guide explains the differences, the use cases, and the gotchas that trip people up.
Regex looks like noise but it is just a tiny pattern language. This guide teaches the mental model, the most useful metacharacters, the traps, and a workflow for testing patterns without copy-pasting into random websites.
A practical guide to creating passwords that are both uncrackable and memorable: passphrases, password managers, and the one rule that actually matters. Includes a free browser tool to check any password’s strength.
Learn what DNS records are, the most common record types (A, AAAA, MX, TXT, NS, CNAME, SOA, CAA), how to look them up from your browser, and how to use them to verify that a domain points where you think it does.
Standard deviation sounds intimidating but it is just a measure of how spread out your numbers are. Learn what it means, when to use it, and how to calculate it by hand and with a free browser tool.
A practical guide to writing meta descriptions that boost click-through rates, with length rules, examples, and a free browser tool to check yours against Google’s recommended range.
Learn what two-factor authentication really does, how time-based one-time passwords (TOTP) work, why codes change every 30 seconds, and how to inspect your own codes without an authenticator app.
Learn what JWTs are made of, how to decode and verify them, the most common mistakes developers make, and how to inspect a token in your browser without sending it anywhere.
A curated list of the best free online image tools that run in your browser, no upload, no signup. Convert between JPG, PNG, and WebP, compress, resize, crop, and more.
A practical comparison of JSON, YAML, and TOML: syntax, features, readability, tooling support, and when each format is the right choice for config files, data exchange, and APIs.
Learn 5 free ways to merge PDF files into a single document, including the fastest browser-based method. No upload, no signup, no watermarks.
Learn how to shrink a PDF file to 30-70% of its original size without visible quality loss. 5 free methods, including the fastest browser-based approach.
A practical guide to Base64 encoding: what it is, how it works, when to use it, and when to use something else. With examples and a free browser-based encoder.
Learn how to resize images for web, email, and social media without losing quality. 5 free methods including the fastest browser-based approach.
Learn how monthly mortgage payments are calculated, including the formula, an amortization example, and what the numbers mean for your loan. With a free mortgage calculator.
A practical comparison of HEX, RGB, and HSL color formats: when to use each, how to convert between them, and why one of them is the right choice for your next project.
A curated list of the best free online developer tools that run in your browser, no signup, no uploads, no tracking. 100 tools for formatting, encoding, testing, and more.
Learn what JSON formatting is, why it matters, and how to pretty-print, minify, and validate JSON. Includes common pitfalls, real examples, and a free browser-based JSON formatter.
A practical guide to UUID versions — what v1, v4, v5, and v7 are, how they differ, and why UUID v7 is the right default for new database primary keys in 2026.
A complete guide to cron expressions: what each field means, common patterns, special characters (* ? / , -), day-of-week gotchas, and how to test your cron before shipping it.
A practical comparison of JPEG, PNG, WebP, AVIF, and SVG: when to use each, how they handle transparency and animation, browser support in 2026, and how to pick the right format for the job.