Code faster,
debug smarter.
A collection of free online developer tools — format, validate, encode, decode, and debug code and data without installing anything. 21 tools, 100% free, dark mode by default.
Categories
Tools organized by what you need
Six categories covering every essential developer task — from formatting to generating to comparing.
Format
3 toolsEncode/Decode
5 toolsGenerate
3 toolsConvert
3 toolsTest & Compare
2 toolsMinify
3 toolsAll Tools
21 developer tools, all free
Every essential developer tool in one clean, fast, dark-mode interface. No ads in the working area.
JSON Formatter
Format, beautify, and validate JSON with syntax highlighting and error detection.
FormatJSON Validator
Validate JSON syntax and get detailed error messages with line and column numbers.
ValidateXML Formatter
Format and beautify XML documents with proper indentation and structure.
FormatHTML Minifier
Minify HTML by removing whitespace, comments, and unnecessary characters.
MinifyCSS Minifier
Compress CSS files by removing comments, whitespace, and optimizing selectors.
MinifyJS Minifier
Minify JavaScript code while preserving functionality and reducing file size.
MinifyBase64 Encoder
Encode any text or file to Base64 format for safe data transmission.
EncodeBase64 Decoder
Decode Base64 strings back to readable text or downloadable files.
DecodeURL Encoder
Encode URLs and query parameters to safely include special characters.
EncodeURL Decoder
Decode percent-encoded URLs back to their original readable format.
DecodeHTML Entity Encoder
Convert special characters to HTML entities for safe display in web pages.
EncodeJWT Decoder
Decode JSON Web Tokens and inspect header and payload in readable JSON.
DecodeRegex Tester
Test regular expressions against text with real-time matching and group capture.
TestColor Converter
Convert colors between HEX, RGB, HSL, and CMYK formats with live preview.
ConvertUUID Generator
Generate RFC 4122 compliant UUIDs (v1, v4, v5) in bulk with one click.
GenerateHash Generator
Generate MD5, SHA1, SHA256, and SHA512 hashes from any text input.
GenerateTimestamp Converter
Convert Unix timestamps to human-readable dates and vice versa across timezones.
ConvertCron Expression Parser
Parse and explain cron expressions with human-readable descriptions and next run times.
ParseYAML to JSON
Convert YAML configuration files to JSON format and validate structure.
ConvertMarkdown Preview
Preview Markdown in real-time with GitHub-flavored styling and syntax highlighting.
PreviewDiff Checker
Compare two text snippets and visualize differences with line-by-line highlighting.
CompareWhy DevKit
Built by developers, for developers
Every detail — from dark mode to large file support to keyboard shortcuts — is designed for the developer workflow.
21 Tools in One Place
Stop bookmarking 10 different sites. DevKit has every essential developer tool in one clean, fast interface.
Handles Large Files
Process JSON, XML, and other files up to 10MB+ without freezing or crashing. Web Workers keep the UI responsive.
Dark Mode by Default
Built for developers who work at night. Dark mode is the default, not an afterthought. Easy on the eyes.
All Client-Side
Every tool runs in your browser. No data sent to servers. Your code and data never leave your device.
No Ads in Tool Area
Ads only appear in the sidebar, never in the working area. Your coding space stays clean and distraction-free.
Keyboard Shortcuts
Power-user keyboard shortcuts for formatting, copying, clearing, and switching tools. Code at the speed of thought.
Who Uses DevKit
Tools for every developer
From frontend to DevOps to QA — DevKit serves anyone who writes, tests, or debugs code.
Frontend Developers
Format JSON API responses, minify CSS/JS for production, convert colors, and test regex patterns.
Backend Developers
Decode JWTs, generate UUIDs, parse cron expressions, and convert timestamps across timezones.
DevOps Engineers
Generate hashes, parse cron schedules, encode/decode Base64, and convert YAML to JSON for configs.
QA Testers
Test regex patterns, decode JWT tokens, compare text diffs, and validate JSON payloads from APIs.
Students & Learners
Learn JSON structure, understand encoding, experiment with regex, and preview Markdown — all in one place.
API Developers
Format JSON responses, encode URL parameters, generate API keys (UUIDs), and decode JWT auth tokens.
Comparison
DevKit vs other dev tool sites
See why DevKit is the best free developer toolkit available online.
| Feature | DevKit | JSONFormatter | DevTools.io | Dev.to |
|---|---|---|---|---|
| Price | 100% Free | Free (ads) | Free (ads) | Free |
| Total Tools | 21 | 1-2 | 5-10 | N/A |
| Large File Support | 10MB+ | Slow | Limited | N/A |
| Dark Mode | Default | Optional | No | N/A |
| Ads in Tool Area | No | Yes (heavy) | Yes | N/A |
| All in One Place | Yes | No | Partial | N/A |
| Client-Side | 100% | Yes | Mostly | N/A |
Testimonials
Trusted by developers worldwide
Join thousands of developers who use DevKit as their daily driver for code utilities.
DevKit replaced 5 bookmarks for me. The JSON formatter handles 5MB API responses without freezing — something that broke on every other online tool I tried.
The JWT decoder and cron parser are my daily drivers. Clean UI, dark mode by default, no ads in the working area — it's clearly built by someone who actually codes.
Having YAML-to-JSON, Base64, and hash generation in one place saves me so much time during deployments. The large file support is genuinely impressive.
The regex tester with real-time matching and the diff checker are perfect for validating test data. No more switching between 3 different tabs during test sessions.
FAQ
Questions? We've got answers
Are all DevKit tools really free?
Yes! All 21 developer tools are 100% free with no signup, no premium tiers, and no feature limits. The site is supported by non-intrusive sidebar ads — never in the tool working area.
Can DevKit handle large files?
Yes. We use Web Workers for processing, which means the UI stays responsive even with 10MB+ JSON or XML files. Most online tools freeze or crash on large files — DevKit handles them smoothly.
Is dark mode the default?
Yes. DevKit defaults to dark mode because most developers prefer it. You can switch to light mode if needed, and your preference is saved locally.
Do you store my code or data?
No. Every tool processes data entirely in your browser. Your code, JSON, tokens, and files never leave your device. There are no server-side processing or storage.
Are there keyboard shortcuts?
Yes! We support keyboard shortcuts for common actions — format (Ctrl+Shift+F), copy (Ctrl+Shift+C), clear (Ctrl+Shift+X), and tool switching. Check the shortcuts panel in each tool.
Can I use DevKit offline?
Once loaded, most tools work offline since processing is client-side. However, you need an internet connection to initially load the page and for ad rendering.
How accurate are the tools?
We use the same industry-standard libraries that power enterprise tools — json5 for JSON, js-yaml for YAML, crypto-js for hashing, etc. Results are accurate and reliable.
Can I suggest a new tool?
Absolutely! We built DevKit based on community feedback. If you need a tool that isn't here, contact us and we'll consider adding it in the next update.
Your complete dev toolkit is one click away
Open DevKit and start formatting, encoding, and debugging — 21 free tools, dark mode, no signup.
Get in Touch
Have a question, feedback, or need help? Send us a message and we’ll get back to you within 24 hours.