Tools for everyday web development: JSON formatting and validation, CSS/JS/HTML minification, SQL formatting, regular expression testing, JWT decoding and generation, Cron expression parsing, YAML ⇄ JSON conversion, Markdown to HTML, and more. Everything runs locally in your browser — no data leaves your machine.
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Decode JWT tokens in real time. Header, Payload, and Signature displayed with color coding. Expiry check included.
Format and indent SQL queries for readability. Keywords are placed on new lines automatically.
Minify JavaScript by removing comments and extra whitespace. Shows before/after size comparison.
Format, validate, and beautify JSON in real time. Syntax highlighting, error line numbers, copy and download supported.
Generate cron expressions with a GUI. Set minute, hour, day, month, and weekday with preset buttons.
Automatically generate TypeScript interfaces from JSON objects. Supports nested objects and arrays.
Convert numbers between binary (2), octal (8), decimal (10), and hexadecimal (16) simultaneously.
Generate HS256-signed JWT tokens with custom claims (sub, iss, exp, aud) and a secret key.
Test regular expressions in real time. Match highlighting, group capture, and flag controls (g, i, m).
Calculate the difference between two dates in days, hours, minutes, and seconds. Total values included.
Convert Markdown to HTML with live preview. Supports headings, bold, italic, links, lists, code blocks.
Convert JSON to YAML format instantly in your browser. Clean, readable YAML output.
Convert YAML to JSON in your browser. No server required. Supports nested objects and arrays.
Convert JSON arrays to CSV format. Auto-detects headers from all objects. Choose delimiter.
Convert CSV data to JSON arrays. Custom delimiter support with quoted field handling.
Minify CSS by removing comments, whitespace, and unnecessary characters. Shows compression percentage.
Minify HTML by removing whitespace and optional comment stripping. Shows compression ratio.
Minify JSON in real time. Shows before/after byte size and reduction rate.
Convert color codes between HEX, RGB, and HSL formats. Color picker included for quick selection.
Compare two JSON objects and show differences by path. Added, removed, and changed values highlighted.
Encode special characters to HTML entities (&, <, >) or decode them back to plain text.
Paste HTML source to extract all meta tags, title, OGP, and Twitter Card tags in a structured table.
Parse cron expressions into human-readable descriptions. Shows next 5 execution times.
Display the current Unix timestamp in seconds, milliseconds, ISO 8601, UTC, and local time. Freeze & copy.
Convert Unix timestamps (seconds or milliseconds) to readable dates and vice versa. Auto-detects format.
Everything about ISO 8601 — the YYYY-MM-DDTHH:mm:ssZ format, timezone offsets (Z vs +00:00), durations, week numbers, and how to use it in JavaScript, Python, PHP, SQL, and HTML.
Everything you need to know about Cron expressions — the five-field syntax, special characters, common schedule patterns, timezone gotchas, and how Cron works in GitHub Actions, AWS EventBridge, Laravel, and Kubernetes.
How to convert JSON to TypeScript interfaces automatically — the type mapping rules, how to handle null values, common patterns for API response wrappers, and when to use Zod for runtime validation instead of plain interfaces.
The complete reference for CSS gradients — syntax, color stops with position %, transparency, gradient text, border effects, and layered backgrounds. Includes copy-ready code for linear-gradient, radial-gradient, and conic-gradient.
A practical guide to CSV files. Learn the format, how to handle commas inside values, why Excel mangles UTF-8 on Mac, and when converting to JSON makes sense — with code examples in JS and Python.
Understand the three color formats used in CSS — HEX, RGB, and HSL. Covers when to use each, how to add opacity with rgba() and hsla(), 8-digit hex with alpha, and converting between formats.
A beginner's guide to Markdown — the lightweight syntax behind GitHub READMEs, Notion, and dev.to. Includes a full cheat sheet, rendered HTML examples, and notes on GitHub Flavored Markdown differences.
Timezone bugs are subtle and painful. Learn the difference between UTC offsets and named zones, why you should always store UTC in your database, and how to handle DST correctly in JavaScript and Python.
Rich snippets — star ratings, FAQs, breadcrumbs in search results — come from structured data. Learn how JSON-LD works, why Google prefers it over Microdata, and how to implement Article and FAQ schema.
Understand color contrast ratios and WCAG AA/AAA requirements. Covers the 4.5:1 threshold, how to find darker shades that pass, common failures like light-gray text, and tools to verify your palette before launch.
A beginner's guide to YAML. Covers indentation rules, data types, multi-line strings, and comments — with side-by-side JSON comparisons. Explains why YAML is used in Docker Compose, GitHub Actions, and Kubernetes configs.
Learn SQL formatting conventions with before/after examples. Covers keyword capitalization, one-clause-per-line rules, subquery indentation, and leading vs trailing commas — plus how to auto-format in one click.
Understand how text diff tools work. Covers unified diff format, line-level vs character-level comparison, how Git uses diff, and practical uses in code review, config management, and document editing.
Date formatting confusion is surprisingly common. Learn the most widely used date formats — ISO 8601, RFC 2822, US-style MM/DD/YYYY — what each means, when to use them, and how to convert between them without bugs.
A clear, practical introduction to JSON. Learn the syntax, data types, real-world use cases in REST APIs and config files, and common pitfalls like missing commas and unsupported comments.
A practical breakdown of JWT structure — header, payload, signature. Covers the full auth flow, how signature verification works, where to store tokens, and JWT vs session cookies.
Learn how minification reduces file size by removing whitespace, comments, and redundant code. Includes before/after examples, minification vs gzip, and how to integrate it into your build process.
Learn how Open Graph meta tags control how your pages look when shared on Slack, Twitter, and Facebook. Covers required tags, og:image size guidelines, Twitter Card differences, and debugging tools.
A practical introduction to regex with real examples. Learn the most useful metacharacters, then apply them to email validation, phone numbers, URLs, and dates — with patterns you can copy straight away.
Understand Unix timestamps from first principles. Learn what epoch time is, how to convert between timestamps and human-readable dates in JavaScript, Python, and PHP, and what the Year 2038 problem means.
The JSON Formatter is the most-used tool on Devryo — paste any JSON to instantly validate and format it. The CSS Minifier and JS Minifier are great for quick optimization work without a build pipeline.