Guides & Articles
Short, practical guides on formatting, encoding, and everyday developer tasks — each paired with the free tool that does the work.
What Is Unix Time? Epoch, Seconds & the Year 2038 Problem Unix time explained — what the epoch is, why time is counted from 1970, seconds vs milliseconds, leap seconds, and the Year 2038 problem. Unix Timestamp Converter Web Security Essentials for Developers The security fundamentals every developer needs — authentication and tokens, storing passwords safely, transport security, and where encoding fits — with focused deep-dives. JWT Decoder Regex Groups, Backreferences & Lookarounds The advanced-but-everyday regex features — capturing and named groups, alternation, backreferences, and lookahead/lookbehind assertions. Regex Tester Regex Character Classes, Quantifiers & Anchors The core building blocks of every regex — character classes and shorthands, greedy vs lazy quantifiers, and the anchors that pin a match to a position. Regex Tester ISO 8601 & UTC: Date Formats and Time Zones Explained How to write dates that never get misread — the ISO 8601 format, what UTC and the Z suffix mean, time-zone offsets, and daylight-saving pitfalls. Unix Timestamp Converter HTTP Request Methods: GET, POST, PUT, PATCH & DELETE What each HTTP method means, the difference between safe and idempotent, and which verb to use for reading, creating, updating, and deleting. cURL Formatter How to Store Passwords Securely Why you hash (not encrypt) passwords, what salting does, which slow algorithms to use (bcrypt, scrypt, Argon2), and the mistakes that cause breaches. Password Generator How JWT Authentication Works How JSON Web Tokens are used for stateless authentication — the header/payload/signature structure, how verification works, and the security caveats. JWT Decoder Encoding vs Encryption vs Hashing: A Developer's Guide The three are constantly confused. This guide explains what encoding, encryption, and hashing each do, when to use which, and the mistakes that cause real security bugs. Base64 Encode / Decode The Complete Guide to Regular Expressions Regex end to end — literals, metacharacters, character classes, quantifiers, anchors, groups, and flags — with focused deep-dives and a live tester. Regex Tester The Complete Guide to HTTP for Developers HTTP end to end — what it is, the anatomy of a request and response, methods, status codes, and headers — with links to focused deep-dives and tools. HTTP Status Code Lookup The Complete Guide to Dates and Times for Developers How computers represent time — epoch timestamps, UTC and time zones, ISO 8601, and scheduling — with focused deep-dives and tools. Unix Timestamp Converter Character Encoding: ASCII, Unicode & UTF-8 Explained Why text is bytes, how ASCII, Unicode, and UTF-8 relate, and what causes those mojibake question-mark characters — explained for developers. URL Encode / Decode Base64 Is Not Encryption: Encoding vs Security Base64 looks scrambled, so people treat it as a way to hide data. It isn't. Here's why Base64 offers zero security, and what to use when you actually need secrecy. Base64 Encode / Decode Anatomy of an HTTP Request and Response A line-by-line breakdown of an HTTP request and response — the request line, status line, headers, and body — so raw HTTP stops looking like noise. HTTP Headers Parser How to Test JSONPath Expressions A practical guide to JSONPath syntax — child access, wildcards, recursive descent, array slices, and filters — with runnable examples. JSONPath Tester How to Read a Cron Expression Decode the five fields of a cron schedule — minute, hour, day, month, weekday — plus ranges, steps, lists, and the day-of-month/day-of-week rule. Cron Expression Parser How to Generate a Strong Password What actually makes a password strong — length, character variety, and entropy — and why a generator beats picking one yourself. Password Generator How to Convert Unix Timestamps Understand Unix time — seconds vs milliseconds, UTC vs local, and how to convert an epoch timestamp to a human date and back. Unix Timestamp Converter How to Compare Two JSON Files Find what changed between two JSON documents with a structural diff — added, removed, and changed values by path, ignoring formatting. JSON Diff How to Generate Rust Structs from JSON Turn a JSON sample into Rust serde structs — snake_case fields, serde rename, Option for nullable fields, and Vec for arrays. JSON to Rust How to Generate Kotlin Data Classes from JSON Turn a JSON sample into Kotlin data classes — camelCase properties, @SerialName, nullable types with defaults, and List for arrays. JSON to Kotlin How to Generate Java Records from JSON Turn a JSON sample into Java records — camelCase components, Jackson @JsonProperty, boxed types for nullable fields, and List for arrays. JSON to Java How to Convert TOML to JSON (and Back) Convert TOML config to JSON and JSON to TOML — how tables, arrays of tables, inline tables, and TOML's typed values map across. TOML to JSON Converter How to Convert a Query String to JSON (and Back) Parse a URL query string into JSON and serialize JSON back — how repeated keys, bracket notation, and encoding are handled. Query String to JSON Converter How to Convert a .env File to JSON (and Back) Convert dotenv files to JSON and JSON to .env — how comments, quotes, the export prefix, and nested values are handled. .env to JSON Converter HTTP Status Codes Explained (1xx–5xx) What HTTP status code classes mean, the codes you'll actually hit, and how to tell a client error from a server error. HTTP Status Code Lookup How to Read and Parse HTTP Headers The anatomy of HTTP request and response headers, how to turn raw headers into JSON, and why duplicates become arrays. HTTP Headers Parser How to Generate TypeScript Interfaces from JSON Turn a JSON API response into TypeScript interfaces — how nested objects, arrays, optional fields, and unions are inferred, and what to check. JSON to TypeScript How to Generate Python Dataclasses from JSON Turn a JSON sample into typed Python dataclasses — how nested objects, optional fields, and null values are handled, and how to adapt for Pydantic. JSON to Python How to Generate Go Structs from JSON Turn a JSON sample into Go structs with json tags — field naming, initialisms, pointers for optional fields, and omitempty. JSON to Go How to Generate C# Classes from JSON Turn a JSON sample into C# classes for System.Text.Json — property naming, attributes, nullable types, and Newtonsoft compatibility. JSON to C# How to Format a Long cURL Command Why long curl commands are hard to read, how to break them across lines with backslash continuations, and how quoting works. cURL Formatter How to Convert XML to JSON How XML maps to JSON, how attributes and repeated elements are represented, and why values stay strings. XML to JSON Converter How to Convert JSON to YAML How JSON maps to YAML, why some strings must be quoted, and how to convert JSON into clean, readable block-style YAML. JSON to YAML Converter How to Convert JSON to XML How JSON maps to XML, how arrays and top-level arrays are handled, and why some keys get sanitized — with clear examples. JSON to XML Converter What Is JSON? A Beginner's Guide JSON explained in plain English — what it stands for, what it looks like, why it's everywhere in modern development, and how to read it. JSON Formatter & Validator What Is a UUID? Versions, Uses, and How to Generate One UUIDs and GUIDs explained — what they are, why v4 is the common choice, how unique they really are, and when to use them. UUID / GUID Generator URL Encoding Explained: When and How to Percent-Encode What URL (percent) encoding is, which characters need it, the space and plus-sign gotcha, and when to encode. URL Encode / Decode MD5, SHA-1 & SHA-256: Hashing Explained What a hash function is, how MD5, SHA-1, SHA-256 and SHA-512 differ, and why hashing is not encryption. Hash Generator JSON vs XML vs YAML vs CSV: When to Use Each A practical comparison of JSON, XML, YAML, and CSV — the same data in each format, their strengths and trade-offs, and how to choose. JSON Formatter & Validator JSON Syntax Rules Explained (With Examples) Every JSON syntax rule that matters, with valid and invalid examples side by side — quotes, commas, keys, and the types JSON allows. JSON Formatter & Validator HTML Minification: Shrink Your HTML for Faster Loads What HTML minification removes, how much it saves, when to minify vs beautify, and how it helps page speed. HTML Minifier & Beautifier How to Test and Debug Regular Expressions A practical approach to writing and debugging regex — flags, capture groups, common tokens, and how to test a pattern against real text. Regex Tester How to Preview Markdown (and Convert It to HTML) A quick reference to Markdown syntax and how to preview it as rendered HTML you can copy into any project. Markdown Previewer How to Format and Validate XML What makes XML well-formed, the rules parsers enforce, and how to format messy XML and catch errors. XML Formatter & Validator How to Decode a JWT (JSON Web Token) What a JWT is made of, how to decode its header and payload, and the crucial difference between decoding a token and verifying it. JWT Decoder How to Convert YAML to JSON How YAML maps to JSON, the indentation and type rules to know, and how to convert config from YAML to JSON reliably. YAML to JSON Converter How to Convert JSON to CSV How to flatten a JSON array into CSV for spreadsheets — what converts cleanly, how nested data is handled, and common pitfalls. JSON to CSV Converter How to Convert CSV to JSON How CSV maps to JSON, the header and quoting rules that matter, and how to convert a CSV file into clean structured JSON. CSV to JSON Converter CSS Minification: Why and How to Minify Your CSS What CSS minification does, how much it saves, when to minify vs beautify, and how it fits a fast-loading site. CSS Minifier & Beautifier The Complete Guide to JSON: Syntax, Types & Common Errors A practical, complete guide to JSON — what it is, its data types, the exact syntax rules, how it compares to XML/YAML/CSV, and the errors that trip people up. JSON Formatter & Validator Common JSON Errors and How to Fix Them The JSON parse errors you'll actually hit — unexpected token, trailing comma, bad quotes — what each means, and how to fix them fast. JSON Formatter & Validator HEX, RGB, HSL & CMYK: A Guide to Color Formats What HEX, RGB, HSL and CMYK mean, how they differ, and when to use each when working with color on the web. Color Converter What Is Base64 Encoding? A Simple Explanation Base64 explained in plain English — what it is, why developers use it, how it works, and when you should not use it. Base64 Encode / Decode How to Validate JSON in JavaScript The reliable way to check whether a string is valid JSON in JavaScript, how to read parse errors, and common mistakes to avoid. JSON Formatter & Validator