Guides & tutorials
Practical, no-fluff guides on JSON, YAML, and TOML configuration files.
Base64 URL-Safe Encoding Explained
Standard Base64 breaks in URLs because of + / and =. URL-safe Base64 fixes it. Learn the differences, where it is used (JWT), and how to convert.
Common Regex Patterns: Email, URL, Phone & More
Copy-paste regular expressions for email, URL, phone, IP address, hex color, and more — with explanations and a free regex tester to validate them.
encodeURIComponent vs encodeURI: What's the Difference?
encodeURIComponent and encodeURI both percent-encode, but they protect different characters. Learn which to use for query parameters versus full URLs.
Epoch Time Explained (and the Year 2038 Problem)
Epoch time is the foundation of how computers track time. Learn what the Unix epoch is, why 1970 was chosen, and the looming Year 2038 problem.
How to Base64 Encode and Decode in JavaScript
Encode and decode Base64 in JavaScript the right way — btoa, atob, and the UTF-8-safe approach with TextEncoder. Plus Node.js Buffer examples.
How to Compare Two Text Files (Diff)
Comparing two versions of text or code is a daily task. Learn how diffs work, what added and removed lines mean, and how to compare text online.
How to Convert a Unix Timestamp to a Date
Convert a Unix timestamp to a human-readable date in JavaScript, Python, SQL, and online — plus the seconds-vs-milliseconds gotcha.
How to Convert CSV to JSON
Convert spreadsheet CSV into a JSON array of objects — how headers become keys, parsing pitfalls with quotes and commas, and a free CSV to JSON tool.
How to Convert JSON to CSV
Turn a JSON array of objects into CSV for spreadsheets — how the mapping works, handling nested fields and commas, and a free online JSON to CSV tool.
How to Convert JSON to XML
Convert JSON to XML and back — how objects map to elements, how arrays and attributes are handled, and a free online JSON to XML converter.
How to Create and Sign a JWT
Create a JSON Web Token step by step — build the header and claims, sign with HS256, and produce a token. With code and a free online JWT generator.
How to Decode a JWT
Decode a JSON Web Token to read its header and payload — online, in JavaScript, and on the command line. Plus why decoding is not the same as verifying.
How to Decode Base64 Online (and in Code)
Decode Base64 back to text or binary — online instantly, or in JavaScript, Python, and the command line. With UTF-8 gotchas and a free decoder tool.
How to Fix Common YAML Errors (Indentation, Tabs, and More)
The most common YAML errors explained in plain English — bad indentation, tab characters, unquoted special characters, and duplicate keys — with copy-paste fixes for each.
How to Flatten Nested JSON for CSV Export
CSV is flat but JSON nests. Learn strategies to flatten nested objects and arrays into columns so your data exports cleanly to a spreadsheet.
How to Generate a UUID in JavaScript
Generate UUIDs in JavaScript the modern way with crypto.randomUUID, plus Node.js options and why you should avoid Math.random for IDs.
How to Read a Cron Expression
Cron expressions schedule recurring jobs with five fields. Learn what each field means, how to read the symbols, and common examples explained.
How to Verify a JWT Signature
Verifying a JWT signature is what makes it trustworthy. Learn how HS256 and RS256 verification works, what claims to check, and how to validate a token.
ISO 8601 Date Format Explained
ISO 8601 explained — the standard date and time format like 2026-06-11T14:30:00Z, what each part means, timezone offsets, and why it sorts correctly.
JSON vs XML: Which Should You Use?
JSON and XML both structure data, but JSON is lighter and XML is more expressive. Compare syntax, size, features, and ideal use cases.
JSON vs YAML vs TOML: Which Config Format Should You Use?
A practical, no-fluff comparison of JSON, YAML, and TOML for configuration files — with real examples, gotchas, and a clear recommendation for each use case.
JWT vs Session Cookies: Which Should You Use?
JWTs and server sessions both handle auth, but differently. Compare statelessness, revocation, security, and scaling to choose the right approach.
MD5 vs SHA-256: What's the Difference?
MD5 and SHA-256 are both hash functions, but only one is secure. Compare speed, output size, collision resistance, and when each is appropriate.
Regex Cheat Sheet for Beginners
A concise regular expression cheat sheet — character classes, quantifiers, anchors, groups, and flags — with examples and a free regex tester.
Regex Greedy vs Lazy Quantifiers: What's the Difference?
Greedy vs lazy regex quantifiers explained — why .* matches too much, how adding ? makes it lazy, and when to use each with clear examples.
SHA-1 vs SHA-256: What's the Difference?
SHA-1 vs SHA-256 compared — digest size, security, collision attacks, and why SHA-1 is deprecated and you should use SHA-256 for new work.
Understanding JSON Syntax Errors and How to Fix Them
JSON is strict, and its error messages are cryptic. Here are the most common JSON syntax errors — trailing commas, single quotes, missing commas, comments — and exactly how to fix each.
UUID Versions Explained: v1, v4, and v7
Not all UUIDs are the same. Compare UUID v1 (time + MAC), v4 (random), and v7 (time-ordered) and learn which version to use for your case.
What Are JWT Claims? iss, sub, aud, exp, and More
Understand JWT claims — the registered claims iss, sub, aud, exp, iat, nbf, plus public and private claims — and what each one means in a token's payload.
What Is a Hash Function?
Hash functions turn any input into a fixed-size fingerprint. Learn what they are, key properties, common algorithms, and what they're used for.
What Is a JWT (JSON Web Token)? A Complete Guide
JWT explained simply — the three parts of a token, how signing works, what claims are, and when to use JSON Web Tokens. With a free decoder.
What Is a Unix Timestamp?
A Unix timestamp counts seconds since 1970. Learn what it is, why it's used everywhere, how it handles time zones, and the Year 2038 problem.
What Is a UUID and How Does It Work?
UUIDs are 128-bit unique identifiers used everywhere in software. Learn what they are, how uniqueness works, their format, and when to use them.
What Is Base64 Encoding and How Does It Work?
Base64 explained in plain English — what it is, why it exists, how the encoding works step by step, and when to use it. With examples and a free online tool.
What Is URL Encoding (Percent-Encoding)?
URL encoding explained — why spaces become %20, which characters must be encoded, and how percent-encoding keeps URLs valid. With a free online tool.
When and How to URL-Encode Query Parameters
A practical guide to encoding query string parameters — which characters break URLs, how to build query strings safely, and using URLSearchParams.
Why You Should Never Use MD5 for Passwords
MD5 (and even plain SHA-256) are the wrong tools for password storage. Learn why fast hashes are dangerous and what to use instead — bcrypt, argon2.
How to Convert JSON to YAML (and Back) Online
A step-by-step guide to converting JSON to YAML and YAML to JSON — what changes, common pitfalls with quotes and types, and how to do it instantly online.
How to Convert JSON to TOML (and TOML to JSON)
Convert JSON to TOML and back the right way. Learn how nested objects become TOML tables, how arrays of objects map, and the gotchas to avoid.
What Is a TOML File? A Beginner's Guide
TOML explained for beginners — what it is, why projects like Cargo and pyproject use it, its syntax for tables and arrays, and how it compares to JSON and YAML.
How to Format and Prettify JSON
Learn how to format, prettify, and beautify JSON — why indentation matters, 2 vs 4 spaces, and how to clean up minified JSON instantly online.
YAML Anchors and Aliases Explained
YAML anchors (&) and aliases (*) let you reuse blocks and keep config DRY. Learn the syntax, merge keys, and when to use them with practical examples.
How to Comment in JSON (and Why You Can't)
JSON does not support comments — here is why, plus five practical workarounds including JSONC, JSON5, comment keys, and switching to YAML or TOML.
Kubernetes YAML: Common Mistakes and How to Avoid Them
The most common Kubernetes YAML mistakes — indentation, wrong types, string booleans, missing quotes on numbers — and how to catch them before kubectl apply.
JSON vs JSON5 vs JSONC: What's the Difference?
JSON, JSON5, and JSONC compared — what each allows (comments, trailing commas, unquoted keys), where they are supported, and which to use for config.
How to Minify JSON (and When You Should)
Minifying JSON strips whitespace to shrink payloads. Learn what minification does, how much it saves, when to use it versus gzip, and how to do it online.
JSON Schema Validation: A Practical Guide
Learn what JSON Schema is, how to write one, and how to validate JSON against it — with examples of types, required fields, and nested objects.