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Developer Tools

JSON, XML, HTML, CSS, JWT, regex, hashing, encoders — built for developers.

16 tools

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JSON Formatter & Validator

Pretty-print and validate JSON

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JSON Minifier

Minify JSON to one line

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XML Formatter

Pretty-print XML

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HTML Formatter

Pretty-print HTML

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CSS Formatter

Pretty-print CSS

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JavaScript Formatter

Pretty-print JS

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Base64 Encoder/Decoder

Encode & decode Base64

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URL Encoder/Decoder

Percent-encode URLs

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JWT Decoder

Decode JSON Web Tokens

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UUID Generator

Generate UUID v4

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Regex Tester

Test regular expressions

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Cron Expression Explainer

Explain cron schedules in plain English

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Hash Generator (MD5/SHA)

MD5, SHA-1, SHA-256, SHA-512

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Color Picker & Converter

HEX, RGB, HSL

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HTML Entity Encoder/Decoder

Encode special chars to entities

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Markdown Previewer

Live-preview Markdown

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About Developer Tools

WebToolsLabs developer tools cover the daily grind of building and debugging web apps: formatting and validating JSON, XML, HTML, CSS, and JavaScript; encoding and decoding Base64, URL, and HTML entities; decoding JWTs; generating UUIDs; testing regular expressions; explaining cron schedules; hashing text; converting colors; and previewing Markdown. Every tool runs locally so you can safely paste tokens, payloads, and sensitive code.

Who it's for: Web developers, backend engineers, DevOps, QA, technical writers, and anyone who works with APIs, configs, or markup all day.

What you can do here

  • Strict JSON formatter and minifier with line-accurate error messages
  • Prettier-powered HTML, CSS, and JavaScript formatters
  • JWT decoder that shows header/payload claims and expiry status — never sends the token anywhere
  • Cryptographic hash generator (MD5 / SHA-1 / SHA-256 / SHA-384 / SHA-512) via Web Crypto
  • Regex tester with live match highlighting, group capture, and flag toggles
  • Cron explainer that converts standard 5-field cron into plain English

Common use cases

  • Quickly inspecting a webhook payload or API response before writing the integration
  • Decoding a JWT to verify its claims while debugging a 401 error
  • Generating UUIDs for database seeds or test fixtures
  • Sanity-checking a regex before pasting it into production code
  • Reformatting minified CSS pulled from a third-party stylesheet

Frequently asked questions

Is the JWT decoder safe to use with production tokens?
Yes — decoding is pure client-side base64 parsing. The token never leaves your browser. We still recommend rotating tokens you paste into any unfamiliar tool out of habit.
Does the JSON formatter handle large files?
Yes. Multi-megabyte JSON formats smoothly. Files that crash your browser are usually too large for any web tool — split them first.
Are the hashes here suitable for cryptographic verification?
SHA-256/384/512 use the Web Crypto API and are suitable for download checksums and signing inputs. MD5 and SHA-1 are provided for legacy compatibility only — they are not collision-resistant.
Can I use these tools offline?
Yes — once the page has loaded, the developer tools work without a network connection.