Guides · page 13 of 14
Browsing 320 guides, newest first.
YAML to JSON in Python: Convert YAML Files with PyYAML and ruamel.yaml
Python makes YAML-to-JSON conversion easy with PyYAML and ruamel.yaml. Here's how to parse YAML files, convert to JSON, handle edge cases, and convert entire directories of...
YAML vs TOML: Which Config Format Should You Use?
YAML and TOML are both human-readable config formats, but they have different strengths. YAML is more flexible and widely used; TOML is simpler and less error-prone. Here's...
Aspect Ratios Explained: A Complete Guide for Developers and Designers
Every major aspect ratio, what it's used for, and the CSS techniques for maintaining it, padding-bottom hack, the aspect-ratio property, and object-fit.
Catastrophic Backtracking: The Regex That Kills Your Server
One regex with nested quantifiers can reduce your server to 100% CPU in milliseconds. This is how catastrophic backtracking works, how to spot it, and how to fix it.
Character Limits Cheatsheet: Every Limit That Matters for Developers
Meta titles, descriptions, Twitter, SMS, Open Graph, HTTP headers, SQL identifiers, every character limit you'll actually hit, with the Unicode caveats that will bite you.
Comparing JSON Structurally (Not Just as Strings)
Two JSON documents can be byte-different and semantically identical. Or byte-identical and structurally inequivalent. Here's how to compare JSON the right way.
Cron Expression Syntax, Explained by Field
Five fields, nine special characters, a dozen edge cases. A complete reference for cron syntax, minute, hour, day, month, weekday, with annotated real-world examples.
Cron Pitfalls: Timezones, DST, and Missed Runs
Your cron job will run twice or skip entirely when DST changes. Here's why, how UTC solves it, and how to configure timezone-aware schedulers correctly.
CSV Quoting and Escaping Rules (the Real Ones, Not the Folklore)
CSV looks trivial until your spreadsheet has a comma in a name field. Here's the actual RFC 4180 rules, the dialects everyone forgets, and how to stop breaking imports.
Hex, RGB, HSL, OKLCH: Which to Pick in 2026
Four CSS color formats, four different audiences. This is what each is good at, why OKLCH is the 2026 upgrade, and a practical guide for which to use where.
How Diff Tools Work: Myers Algorithm, Unified Format, and Merge Conflicts
A technical walkthrough of how diff works: the Myers algorithm, the three output formats, and what those conflict markers in your code actually mean.
How QR Codes Work: and How to Make Ones That Actually Scan
QR codes aren't magic. Finder patterns, Reed-Solomon error correction, version sizing, plus practical rules for making QR codes that scan reliably.
How Secure Is My Password? Entropy, Crack Times, and What Actually Matters
Password security measured in bits of entropy, real hashcat benchmarks on RTX 4090 hardware, crack-time tables, and why length beats complexity every time.
Decoding a JWT Is Not the Same as Verifying It
Every JWT bug in production reduces to the same mistake: trusting a decoded token without verifying its signature. The difference, the consequences, and how to do it right.
JWT Security Checklist for 2026
Twelve checks every JWT implementation should pass before shipping. The actual checklist used by security teams, with the failure mode each prevents.
MD5 Is Dead. Use These Instead.
MD5 was broken in 2004 and is trivially cracked for passwords. Here's what to use instead for checksums, passwords, and message authentication, and why it matters.
Percent Encoding and RFC 3986 Explained
Why is `+` sometimes a space and sometimes a literal plus? Why does `%2520` show up in your logs? RFC 3986 percent-encoding, end to end, with the rules nobody quite remembers.
Private IP Address Ranges, Subnets, and CIDR Notation Explained
The three RFC 1918 private ranges, what CIDR notation actually means, subnet masks, loopback, APIPA, and how to read your machine's network config.
The 2026 Regex Cheatsheet (PCRE, JS, Python: Side by Side)
A dense reference for modern regex: anchors, character classes, quantifiers, lookarounds, capture groups, named groups, Unicode, and the dialect differences that actually bite.
SQL Style Guide: The Things That Actually Matter
Keyword casing, indentation, naming conventions, CTEs vs subqueries, the practical style rules that make SQL readable and maintainable across a team.
Unix Timestamps and Timezones: What Can Go Wrong
Unix timestamps are always UTC, but displaying, parsing, and storing them is where most timezone bugs live. The common pitfalls and exactly how to avoid them.
URL Encoding: The 7 Bugs That Break Your API
Every API has at least one URL-encoding bug. Here are the seven I see most, what each looks like in production, the symptom, and the fix.
UUID v4 vs v7 for Databases: The Benchmark You Need
UUID v4 fragments your primary key index. UUID v7 fixes it with millisecond-ordered timestamps. Here's the benchmark data, why it matters, and when to switch.
WCAG Contrast Explained (AA vs AAA, When It Matters)
Color contrast determines who can read your interface. This is the WCAG math, the four thresholds, the difference from APCA, and how to actually fix violations.