Blog
Short, practical guides to everyday developer tasks. Each one links to a free ToolDock tool so you can try it as you read.
RSS feed· 4 min read
CIDR Notation Explained: What /24, /16 and /32 Mean
Learn how CIDR notation like 192.168.1.0/24 works, how to work out netmasks and usable hosts, which ranges are private, and how to split a network into subnets.
Subnet Calculator· 3 min read
Semver Ranges: Caret (^) vs Tilde (~) in package.json
What ^1.2.3 and ~1.2.3 actually allow in package.json, why 0.x versions behave differently, and how semver decides that 1.10.0 is newer than 1.9.0.
SemVer Comparator & Range Checker· 3 min read
Unix Timestamps: Convert Epoch Time to a Date (and Avoid the Usual Bugs)
What a Unix timestamp is, how to tell seconds from milliseconds, how to convert epoch time in JavaScript, Python, SQL and the shell, and time zone bugs to avoid.
Timestamp ↔ Date· 4 min read
Cron Syntax Explained, with 15 Ready-to-Use Examples
Learn the five fields of a cron expression and the special characters *, /, - and comma, then copy tested schedules for crontab, Kubernetes and GitHub Actions.
Cron Job Explainer· 4 min read
UUID v1 vs v4 vs v5 vs v7: Which Version Should You Use?
What each UUID version is built from, why v4 is the safe default, when name-based v5 helps, and why time-ordered v7 is becoming the choice for database keys.
UUID Generator· 4 min read
How to Decode a JWT (and What Each Part Means)
Learn how to decode a JSON Web Token by hand or in your browser, read its header, payload and claims like exp and iat, and why decoding is not verifying.
JWT Encoder/Decoder· 4 min read
chmod Explained: What 755, 644 and 600 Actually Mean
Read Unix file permissions in octal and symbolic form, see what chmod 755, 644, 600 and 777 allow, and pick safe modes for scripts, web files and SSH keys.
chmod Calculator· 3 min read
What Is Base64 Encoding, and When Should You Use It?
How Base64 turns bytes into text, why encoded data grows by a third, how Base64Url differs, and why Base64 is never a way to hide or secure data.
Base64 Encode/Decode