As a developer, I spend a lot of time switching between different tools for formatting, encoding, testing, and debugging. After years of juggling multiple websites and extensions, I decided to build a collection of tools that I actually use every day.
Here are 12 essential developer utilities that have become part of my daily workflow. Best part? They’re all free, require no sign-up, and respect your privacy.
🔐 1. JWT Debugger
Ever received a JWT token and needed to quickly decode it to see what’s inside?
What it does:
- Decodes JSON Web Tokens instantly
- Verifies token signatures
- Shows header, payload, and signature separately
- Perfect for debugging authentication issues
When I use it:
Working with APIs that use JWT authentication, debugging login issues, or verifying token contents before making requests.
📝 2. JSON Formatter & Validator
Dealing with minified JSON from API responses is painful. This tool has saved me countless hours.
What it does:
- Validates JSON syntax instantly
- Beautifies minified JSON
- Shows clear error messages
- Collapses/expands nested objects
When I use it:
Every time I work with API responses, config files, or need to quickly validate JSON structure.
// Before: {"name":"John","age":30,"city":"NYC"}
// After:
{
"name": "John",
"age": 30,
"city": "NYC"
}
🔤 3. Base64 Encoder/Decoder
Need to encode images for CSS or decode base64 strings? This tool handles both.
What it does:
- Encodes text and files to Base64
- Decodes Base64 strings
- Supports image preview
- Works with large files
When I use it:
Embedding images in CSS, working with data URIs, or decoding base64-encoded content from APIs.
🔍 4. Regex Tester
Regular expressions are powerful but tricky. This tool helps me test them in real-time.
What it does:
- Tests regex patterns in real-time
- Highlights matches
- Shows capture groups
- Provides common regex examples
When I use it:
Form validation, text parsing, search and replace operations, or debugging complex regex patterns.
🗄️ 5. SQL Formatter
Reading minified SQL queries is a nightmare. This formatter makes them human-readable again.
What it does:
- Beautifies SQL queries
- Adds proper indentation
- Supports multiple SQL dialects
- Makes complex queries readable
When I use it:
Reviewing database queries, debugging slow queries, or making SQL more maintainable.
/* Before */
SELECT users.name,orders.total FROM users JOIN orders ON users.id=orders.user_id WHERE orders.total>100;
/* After */
SELECT
users.name,
orders.total
FROM users
JOIN orders ON users.id = orders.user_id
WHERE orders.total > 100;
⏰ 6. Cron Expression Generator
Setting up scheduled tasks? This tool generates cron expressions without memorizing the syntax.
What it does:
- Creates cron expressions visually
- Explains schedules in plain English
- Shows next execution times
- Supports all cron formats
When I use it:
Setting up automated tasks, database backups, scheduled reports, or any time-based automation.
🔓 7. Cron Expression Decoder
Already have a cron expression but forgot what it does? This decoder explains it.
What it does:
- Decodes existing cron expressions
- Explains in human-readable format
- Shows upcoming execution times
- Validates cron syntax
When I use it:
Understanding existing cron jobs, debugging scheduled tasks, or documenting automation.
📦 8. JavaScript/TypeScript Minifier
Reduce bundle sizes by minifying your JavaScript and TypeScript code.
What it does:
- Minifies JavaScript and TypeScript
- Removes comments and whitespace
- Reduces file size significantly
- Preserves code functionality
When I use it:
Optimizing production builds, reducing bundle sizes, or preparing code for deployment.
🎨 9. CSS Flexbox Generator
Flexbox is powerful but the syntax can be confusing. This visual generator makes it easy.
What it does:
- Generates flexbox CSS visually
- Live preview of layouts
- Exports ready-to-use code
- Explains each property
When I use it:
Creating responsive layouts, learning flexbox properties, or quickly prototyping designs.
🔢 10. UUID Generator
Need unique identifiers? This generates various UUID versions instantly.
What it does:
- Generates UUID v1, v4, and more
- Creates multiple UUIDs at once
- Bulk generation support
- Copy with one click
When I use it:
Creating database primary keys, generating unique filenames, or testing systems that require UUIDs.
🧪 11. Mock Data Generator
Testing with realistic data? This generates mock data for your projects.
What it does:
- Generates realistic test data
- Supports multiple data types
- Bulk generation
- Customizable formats
When I use it:
Populating test databases, UI testing, API development, or demonstrating features.
✅ 12. Checksum Generator
Verify file integrity and generate checksums for data validation.
What it does:
- Generates MD5, SHA-1, SHA-256 checksums
- Verifies file integrity
- Supports multiple hash algorithms
- Fast processing
When I use it:
Verifying downloaded files, ensuring data integrity, or generating hashes for security purposes.
About the author:
I’m Nicat, a developer who loves building useful tools. Follow me here on DEV for more developer tips and free tool updates!
