Guides & articles
Short, practical engineering guides. Every tool mentioned runs 100% in your browser — nothing to install, nothing uploaded.
Base64 vs Hex Encoding: When to Use Each (Developer Guide)
Base64 vs hex encoding compared: size overhead, readability, common use cases in JWTs, data URLs and git diffs — with a quick decision table for engineers.
Read guide → 2026-10-11How to Decode a JWT: Reading Header, Payload and Signature
Decode any JWT by hand or with a browser tool: how the three parts are encoded, which claims matter (sub, exp, iss, aud) and why decoding is not verification.
Read guide → 2026-10-10UTF-8 Explained: Why One Chinese Character Counts as 3 Bytes
How UTF-8 encodes ASCII, Latin accents, CJK and emoji: byte lengths per code point, why string length disagrees across systems and how to inspect any character.
Read guide → 2026-10-09Cron Expressions: A Field-by-Field Guide with Real Examples
Read and write cron like a native: what the 5 fields mean, steps and ranges, the day-of-month vs day-of-week rule, @daily shorthands and timezone pitfalls.
Read guide → 2026-10-07UUID v4 and v7: The Complete Guide for Databases and APIs
What a UUID actually encodes, v4 vs v7 trade-offs for database indexes, how unique is truly unique, and why UUIDs are not secrets.
Read guide → 2026-10-06Why Your JSON Is Invalid: The 9 Most Common Syntax Errors
Trailing commas, unquoted keys, smart quotes and friends: the nine JSON syntax mistakes that break parsers, with instant fixes and a validation shortcut.
Read guide → 2026-10-05SHA-256 for Developers: Checksums, HMAC and What Hashing Cannot Do
When to use SHA-256 (and when not to), how HMAC adds a secret, why password hashing needs bcrypt or Argon2 instead, and how to verify checksums quickly.
Read guide → 2026-10-04Testing Regular Expressions Safely in Your Browser
A practical regex testing workflow: flags, capture groups and lookarounds visualized, catastrophic backtracking awareness, and why browser testers protect your patterns.
Read guide → 2026-10-03URL Encoding, Percent-Encoding and Query Strings: What Actually Matters
When spaces become %20 or +, the difference between encodeURI and encodeURIComponent, double-encoding bugs and how to debug URLs component by component.
Read guide → 2026-10-02JSON vs YAML vs XML: Choosing the Right Config Format
JSON, YAML and XML compared for configuration and data exchange: readability, schema support, editor safety and where each format still wins today.
Read guide → 2026-10-01How Strong Is Your Password? Entropy Explained Without the Math Degree
Password strength as bits of entropy: length vs character variety, why dictionary words beat complex short strings, and a realistic cracking-time table.
Read guide → 2026-09-30QR Codes: Size, Error Correction and Payload Limits Explained
How QR codes pack data: versions, the four error correction levels, scan distance rules and the payload ceiling — plus what makes a code unscannable.
Read guide → 2026-09-28Text Diff Explained: How Line Diffing Works and When to Trust It
From LCS to character highlighting: how diff tools align two texts, what ignore-options actually compare, and a workflow for reviewing changes without git.
Read guide → 2026-09-27CSS Color Formats: HEX, RGB and HSL Explained with Conversions
When to use hex, rgb() or hsl() in CSS: how each format stores channels, alpha handling, browser support notes and quick mental conversion recipes.
Read guide → 2026-09-26Unix Timestamps, Epochs and Time Zones: The Developer Field Guide
Seconds vs milliseconds confusion, ISO 8601, why local time is a display concern, leap-second trivia and a debugging workflow for wrong dates.
Read guide → 2026-09-25Minifying JSON and CSS Safely: What Must Never Be Removed
What minifiers are allowed to touch: whitespace rules in JSON, strings and url() in CSS, real-world savings numbers and a pre-flight validation checklist.
Read guide → 2026-09-23What a Good Markdown Previewer Renders (GitHub Flavor Included)
Markdown features worth checking in a previewer: tables, task lists, code fences, sanitization behavior and why raw HTML needs care.
Read guide → 2026-09-21Client-Side Tools and Privacy: Why Paste-Anywhere Matters
What actually happens to data on online tool sites, how fully client-side tools differ, threat models for developers and a checklist for vetting any web tool.
Read guide → 2026-09-20Number Bases in Programming: Binary, Hex and What Comes After 36
Why programmers count in bases 2, 8, 10 and 16, how literals work across languages, bit-pair intuition for hex and converting any base up to 36.
Read guide → 2026-09-18camelCase, snake_case and kebab-case: A Field Guide to Naming Conventions
Which naming convention belongs where across languages, URLs and APIs; case conversion pitfalls with acronyms; and why consistency beats preference.
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