Guides & tutorials
Reviewed developer guides with worked examples, limitations and links to the standards or documentation behind the tools.
Featured guide
JWT Decoding vs Verification: The Difference That Prevents Security Bugs
Decoding a JWT only reveals its claims. Verification proves whether the token can be trusted. See the distinction with safe examples and production checks.
cURL to fetch(): Headers, Bodies, Auth and Multipart ExamplesTranslate common cURL requests into browser or Node fetch code while preserving method, headers, JSON bodies, form data and authentication intent.CIDR and IPv4 Subnetting: Worked Examples for DevelopersWork through /24, /26 and /30 networks step by step: masks, ranges, broadcast addresses, usable hosts and the boundaries calculators can and cannot infer.Cron Time Zones and DST: Why Scheduled Jobs Run at the Wrong TimeA practical guide to server time zones, UTC, daylight-saving transitions and the difference between a cron expression and the environment that runs it.CHMOD 755 vs 644 vs 600: Permissions Explained with ExamplesDecode common Unix permission modes, see why files and directories need different execute bits, and avoid insecure recursive chmod fixes.Cron Syntax Explained: 25 Real Schedules and Common MistakesRead five-field cron expressions from left to right, then use 25 realistic schedules to spot day-of-week, step and range mistakes before deployment.JSON to TypeScript: Handling Nulls, Arrays and Optional PropertiesGenerate useful TypeScript from example JSON without pretending one sample proves every possible runtime shape. Covers nulls, arrays and optional fields.JWT Claims Explained: exp, iat, nbf, iss, aud and subA practical reference for common JWT registered claims, with clock-skew notes, validation rules and examples that separate inspection from trust.CORS Preflight Requests Explained with Real OPTIONS ExamplesUnderstand when browsers send an OPTIONS preflight, what headers they ask for, and how a server should answer without weakening cross-origin policy.