Sometimes you just need a straight answer. Not a forum thread, not a tutorial that assumes you know nothing, not a wall of ads with a table buried at the bottom. Just the thing you were looking for. That's what the new Reference section is for.
📚 Introducing the Reference Section
The Reference section is a new permanent part of the site, sitting alongside the tools and calculators. It's organized into three categories, all free and available in English, Spanish, and French.
📋 Cheat Sheets
Quick-lookup tables and condensed references for things you look up constantly but can never quite remember. No preamble, no padding — just the information.
A few worth bookmarking:
- HTTP Status Codes - Every status code class, the pairs people confuse (401 vs 403, 301 vs 308), and tips on picking codes for an API.
- Linux Commands - The commands you actually reach for, organized by task: file operations, permissions, process management, networking.
- Git Commands - Branching, stashing, rebasing, and the undos that save you when something goes sideways.
- Common Ports - Well-known TCP/UDP port assignments at a glance, from FTP and SSH through to HTTPS and DNS.
- CIDR & Subnet Masks - The prefix-to-mask conversion table plus usable host counts, for the moment you're staring at a firewall rule.
- Regex Syntax - Anchors, quantifiers, character classes, groups, lookaheads — all in one place.
- HTTP Headers - Request and response headers you'll encounter, what they do, and what to watch out for.
- Keyboard Shortcuts - Cross-platform shortcuts for the browser, terminal, VS Code, and everyday productivity apps.
- CSS Quick Reference - Selectors, box model, flexbox, grid, and the properties that always need a second look.
- Morse Code Chart - The full International Morse Code alphabet, numbers, and punctuation, with timing rules.
Browse all cheat sheets at /reference/cheatsheets/.
📖 Guides
Deeper reads that explain not just what something is, but how it actually works — with real examples, tables, and the edge cases that matter.
Some that are worth the read:
- How Hashing Works - The avalanche effect with real SHA-256 output, which algorithms are still safe, HMAC, and the right way to store passwords.
- How DNS Works - The full resolution chain from browser cache to root nameserver, with record types and TTL explained.
- How HTTPS & TLS Works - The TLS handshake step by step, certificate chains, and what a browser is actually checking.
- How JWT Works - Header, payload, and signature unpacked; what JWTs guarantee and what they absolutely don't.
- How Base64 & Encoding Work - Why encoding exists, how Base64 maps bytes to characters, and where people get it wrong.
- How Compound Interest Works - The math behind compounding frequency, with year-by-year tables and the Rule of 72.
- How Subnetting Works - CIDR notation, network vs host bits, and how to carve up an address space by hand.
- How Retirement Savings Work - 401(k), IRA, Roth, contribution limits, employer match, and the compounding timeline.
- How Email Authentication Works - SPF, DKIM, and DMARC from the ground up, with what each record actually prevents.
- How Paychecks & Taxes Work - Federal withholding, FICA, marginal vs effective rate, and what every line on a pay stub means.
Browse all guides at /reference/guides/.
🔤 Glossary
Short, precise definitions for the terms that get thrown around without explanation. Every entry links to the related tools and guides on the site.
A few from across the board:
- Hash - Encryption - Digital Signature
- DNS - DHCP - CIDR - NAT
- JWT - OAuth - MFA - CSP
- Compound Interest - APR - APY - Amortization
- BMI - BMR - TDEE - Calorie
- EXIF - Steganography - Hash - Magic Bytes
Browse the full A-Z at /reference/glossary/.
The reference section will keep growing alongside the tools and calculators. If something's missing that you'd find useful, the contact page is always open. As always, everything is free with no sign-up required.