UUID guides

• What Is a UUID? A Plain English Guide

  Learn what a UUID is, what the 36 character format means, how UUIDs stay unique without a central server, and when you should use one.

  4 min read

• UUID v4 vs v7: Which One Should You Use?

  UUID v4 is random, UUID v7 is time ordered. See how each is built, how they affect database indexes, and a simple rule for picking one.

  4 min read

• All UUID Versions Explained: v1 to v8

  A tour of every UUID version defined in RFC 9562. What each one encodes, how to recognise it from the version digit, and which ones are still worth using.

  4 min read

• Should You Use UUIDs as Database Primary Keys?

  The real trade offs of UUID primary keys in PostgreSQL and MySQL: storage size, index fragmentation, security, and why UUID v7 changes the answer.

  4 min read

• How to Generate a UUID in JavaScript, Python, Go, Java, C# and SQL

  Copy and paste snippets for generating UUID v4 and v7 in JavaScript, Node, Python, Go, Java, C#, PostgreSQL, MySQL and the command line.

  3 min read

• UUID vs GUID: Is There Any Difference?

  GUID is Microsoft's name for a UUID. They are the same 128 bit format, with one byte order quirk in .NET and SQL Server that can bite you.

  3 min read

• Can Two UUIDs Collide? The Math Behind Uniqueness

  How likely is a UUID v4 collision really? We work through the birthday problem with real numbers so you can stop worrying, and cover the rare ways collisions actually happen.

  4 min read

• How to Validate a UUID with Regex, Plus Why You Might Not Want To

  A correct regular expression for UUID validation, with variants for specific versions, braces and uppercase, and the built in parsers that are usually a better choice.

  3 min read

JSON guides

• What Is JSON? A Beginner's Guide with Examples

  JSON explained from scratch: what it looks like, the six value types, where it is used, and how it compares to a JavaScript object.

  4 min read

• JSON Syntax Rules and the 10 Most Common Errors

  The complete set of JSON syntax rules, followed by the ten mistakes that cause almost every Unexpected token error, each with a broken and a fixed example.

  3 min read

• JSON vs XML: Which Data Format Should You Use?

  A practical comparison of JSON and XML covering size, readability, schemas, tooling and the cases where XML is still the right answer.

  3 min read

• JSON vs YAML for Configuration Files

  YAML is easier to write and JSON is harder to get wrong. See the real differences, the famous YAML gotchas, and which format to pick for your config.

  3 min read

• JSON.stringify and JSON.parse Explained, Including the Surprises

  How JavaScript converts between objects and JSON text, with the replacer, reviver and indent arguments, and the cases that silently lose data.

  3 min read

• How to Pretty Print JSON from the Command Line

  Format and query JSON in the terminal with jq, Python, Node and PowerShell. One liners for files, curl output and clipboard contents on macOS, Linux and Windows.

  3 min read

• JSON Schema: How to Validate the Shape of Your JSON

  An introduction to JSON Schema with a complete example. Learn type, required, properties, enum, pattern and $ref, and how to run validation in JavaScript and Python.

  4 min read