🧰 DevToolBox

Find the Best Developer Tools

Hand-picked collection of free developer tools for every part of your workflow — from writing code to deploying to production.

Explore by Category

Frontend & Design

Security & Testing

Featured Tools

Build, test, and validate cron expressions with human-readable descriptions. See the next 5 execution times instantly, translate between cron syntax and plain English, and copy-ready schedules for your crontab. Supports standard 5-field cron, extended 6-field with seconds, and special strings like @daily/@hourly. Essential for DevOps engineers managing scheduled jobs, backend developers configuring task runners, and sysadmins maintaining server automation. All parsing runs client-side — your cron expressions never leave your browser.

Compare two texts, code snippets, or JSON side by side with line-by-line diff highlighting. Paste or type your original and modified versions, and instantly see additions, deletions, and changes color-coded for clarity. Supports inline and side-by-side views, word-level diff for granular comparison, and one-click copy of either version. Perfect for code review, comparing configuration files, tracking document revisions, and validating API response changes. All diff computation happens locally in your browser.

Hash & UUID Generator

Generate cryptographic hashes (MD5, SHA1, SHA256, SHA512) and UUIDs instantly. Hash any text or file with a single click, compute checksums to verify file integrity, and generate bulk UUID v4 identifiers for database seeding. Supports HMAC keyed hashing, batch mode for processing multiple inputs at once, and file upload for computing file hashes without uploading to any server. Ideal for developers verifying download integrity, generating unique IDs, and implementing password storage schemes.

All Tools

Format and beautify SQL queries online, 15+ dialects

Format, validate, tree view JSON

Base64 Encoder/Decoder

Encode/decode Base64, URL-safe, file upload

URL Encoder/Decoder

URL encode and decode strings online

HTML Entity Encoder/Decoder

Convert special characters to HTML entities and back

Generate UUID v1, v4, v7 with one click

Decode JWT tokens: view Header and Payload, check expiration, issuer, subject and more

Decode, verify, and debug JWT tokens in browser

Test regular expressions with real-time highlighting

Compare text, code, and JSON side by side

Timestamp Converter

Convert between Unix timestamps and human-readable dates

Color Picker & Converter

Pick colors and convert between HEX, RGB, HSL formats

Compare two texts side by side with line-by-line diff highlighting

CIDR / IPv6 Subnet Calculator

Calculate network, broadcast, subnet mask, usable IP range for IPv4 and IPv6

Hash & UUID Generator

Generate UUID v4 and compute MD5, SHA1, SHA256, SHA512 hashes. Batch mode, file hashing

QR Code Generator & Reader

Generate QR codes from text/URLs, download as PNG. Upload images to decode QR codes

HEX/RGB/HSL converter, color picker, palette generator, random colors

CSS/JS Minifier

Compress CSS and JavaScript, or beautify with proper formatting

Image Compressor

Compress PNG, JPG, WebP images — adjust quality, resize, download. 100% client-side

Markdown Preview

Write Markdown with live HTML preview. GFM tables, task lists, code highlighting. Export to HTML

Build and test cron expressions with human-readable descriptions and next-execution preview

UUID Generator Pro

Generate UUID v1/v4/v7, GUID, NanoID, ULID — all in browser, zero network requests

Why DevToolBox?

DevToolBox is a free online developer tools platform — no sign-up, no ads, no data collection. Every tool runs directly in your browser, so your data stays private and never touches a server.

Our online JSON formatter helps you format, validate, and explore nested JSON with a collapsible tree view. The base64 encoder handles standard, URL-safe, and file-to-base64 conversions instantly. Need to clean up messy code? Our CSS/JS minifier and HTML minifier online compress your frontend assets for faster page loads. Debug tokens with our JWT debugger, test patterns with the regex tester online, and handle encoding with the URL encoder decoder.

Beyond single-purpose tools, we cover the full developer workflow: SQL formatter for 15+ database dialects, UUID generator for unique identifiers, timestamp converter for date handling, QR code generator for mobile-friendly links, hash generator for MD5/SHA checksums, and image compressor for optimizing assets — all 100% free and client-side.

Whether you're debugging an API response, prepping a production deployment, or just need a quick color picker or markdown preview, DevToolBox has you covered. Bookmark us and keep your favorite developer tools one click away.

Guides & References

Online Regex Tester

Learn how to write and debug regular expressions with real-time matching, flags, and replace support. Complete guide with examples and FAQ.