What tools are in Dev Tools Lab?

Dev Tools Lab includes five browser-based developer utilities: JSON Formatter (format, validate, minify, and explore JSON data), Regex Tester (test regular expressions with real-time matching and capture groups), Hash & Encode Toolkit (generate SHA hashes, encode/decode Base64, URL, and decode JWT tokens), Password & QR Generator (create secure passwords and QR codes), and Diff Checker (compare two texts with highlighted differences).

Do Dev Tools require an account or login?

No. All Dev Tools work entirely in your browser with no server-side processing. You can use them without creating an account or logging in. No data is sent to any server — everything stays private on your device.

Are there usage limits for Dev Tools?

No. Unlike AI-powered tools that have daily limits due to API costs, Dev Tools run 100% in your browser. There are no daily usage limits — use them as much as you need, anytime, for free.

How secure is the Password Generator?

The Password Generator uses the Web Crypto API (crypto.getRandomValues) which provides cryptographically secure random numbers. This is the same standard used by professional password managers. The generated passwords never leave your browser.

Can I use Dev Tools on my phone?

Yes, all Dev Tools are responsive and work in any modern mobile browser. While some tools like the JSON Formatter are easier to use on desktop, the Password Generator and Unit Converter work great on mobile devices too.

Dev Tools Lab – Free JSON Formatter, Regex Tester, Hash & More

Key Features & Benefits

One-Click JSON Formatting

Paste any JSON and instantly format it with proper indentation and line breaks. The formatted output uses 2-space indentation by default, making it easy to read nested objects and arrays at a glance.

Validation with Error Messages

Validate JSON syntax and get clear error messages when something is wrong. The validator pinpoints the issue so you can quickly find and fix malformed JSON, missing commas, or mismatched brackets.

Minify JSON for Production

Compress formatted JSON into a single line with no whitespace — perfect for reducing file sizes before deployment. Minified JSON can save significant bandwidth in production APIs and configurations.

Interactive Tree View

Explore JSON data visually with an expandable tree view. Click to expand or collapse objects and arrays, making it easy to navigate deeply nested structures without scrolling through raw text.

JSON Statistics

See at-a-glance statistics about your JSON: number of objects, arrays, nesting depth, and total byte size. Useful for understanding the complexity and size of your data before processing it.

Copy & Clear with One Click

Copy the formatted or minified output directly to your clipboard, or clear everything to start fresh. No need to select and copy manually — one click does it all.

JSON Formatter – Frequently Asked Questions

What is JSON formatting?

JSON formatting (also called pretty-printing) adds indentation and line breaks to compact JSON, making it readable by humans. For example, a single line like {"name":"John","age":30} becomes a nicely indented multi-line display. This is essential for debugging APIs, editing configuration files, and understanding data structures.

Is my JSON data sent to any server?

No. All JSON processing (formatting, validation, minification, and tree view) happens entirely in your browser using JavaScript's built-in JSON.parse and JSON.stringify functions. Your data never leaves your device.

What does the tree view show?

The tree view renders your JSON as an interactive, expandable hierarchy. Objects and arrays can be collapsed or expanded by clicking the arrow icons. Keys are shown in amber, strings in green, numbers in blue, and booleans in purple for easy visual parsing.

Can I format very large JSON files?

The formatter works with any JSON that your browser can parse. For very large files (over 10MB), your browser may slow down during parsing, but the tool will still work. The tree view has a max height with scrolling to keep the interface responsive.

What is JSON minification?

JSON minification removes all unnecessary whitespace (spaces, tabs, newlines) from formatted JSON, producing the smallest possible valid JSON string. This reduces file size for transmission over networks and is standard practice for production APIs and web applications.

Key Features & Benefits

Real-Time Regex Matching

See matches highlighted in real-time as you type your pattern and test string. Multiple matches are shown in alternating colors (yellow, cyan, pink, lime, orange) so you can easily distinguish between different match groups.

Capture Group Visualization

View all captured groups for each match in a structured display. See the full match and each capture group separately — essential for understanding and debugging complex patterns with multiple groups.

5 Regex Flags Support

Toggle Global (g), Case-insensitive (i), Multiline (m), Dotall (s), and Unicode (u) flags with visual buttons. Each flag shows a description tooltip explaining its purpose.

Common Pattern Presets

Quickly load pre-built patterns for Email, URL, Phone, IP Address, Date, Hex Color, and URL Slug. These presets cover the most frequently needed validation patterns and serve as learning examples.

Interactive Quick Reference

A built-in cheat sheet of 15 essential regex tokens with descriptions. Click any token to append it to your pattern — perfect for learning regex or remembering syntax without leaving the tool.

Instant Error Feedback

Invalid regex patterns are caught immediately with clear error messages. The tool uses JavaScript's native RegExp engine, so the behavior matches exactly what you'll see in your code.

Regex Tester – Frequently Asked Questions

What regex flavor does this tester support?

This tester uses JavaScript's built-in RegExp engine, which follows the ECMAScript specification. This is the same regex engine used in web browsers and Node.js. Most common patterns work identically across JavaScript, Python, and Java, but there are some differences in advanced features like lookbehind assertions and Unicode property escapes.

What are regex flags?

Flags modify how the regex engine processes your pattern. Global (g) finds all matches instead of just the first. Case-insensitive (i) ignores uppercase/lowercase differences. Multiline (m) makes ^ and $ match line boundaries. Dotall (s) makes . match newline characters. Unicode (u) enables Unicode mode for character classes.

Can I use this to test regex for other programming languages?

While the tester uses JavaScript's regex engine, most common patterns (email validation, URL matching, character classes, quantifiers) work identically across JavaScript, Python, Java, PHP, and other languages. Advanced features like named groups, lookbehind, and Unicode properties may behave differently.

What are capture groups?

Capture groups are portions of your regex pattern enclosed in parentheses (). They extract specific parts of a match. For example, the pattern (\d{4})-(\d{2})-(\d{2}) applied to '2025-05-10' would create three capture groups: '2025', '05', and '10'. The tester displays all groups for each match.

Why are my matches showing different colors?

When the Global (g) flag is enabled and there are multiple matches, each match is highlighted in a different color (rotating through yellow, cyan, pink, lime, and orange). This makes it easy to visually distinguish between separate matches in the test string, especially when matches are close together.

Key Features & Benefits

SHA Hash Generation

Generate SHA-1, SHA-256, and SHA-512 cryptographic hashes from any text input using the Web Crypto API. These are the industry-standard hash algorithms used for data integrity verification, password hashing, and digital signatures.

Base64, URL & HTML Encoding

Encode and decode text in Base64, URL-encoded, and HTML-encoded formats with a single click. Switch between all six modes (Base64 encode/decode, URL encode/decode, HTML encode/decode) instantly.

JWT Token Decoder

Decode JSON Web Tokens (JWT) to inspect the header, payload, and signature sections. Automatically detects and displays token expiration times, making it easy to debug authentication issues.

Copy Results Instantly

Every output — hash values, encoded/decoded text, and decoded JWT sections — has a one-click copy button. No need to manually select and copy text.

Browser-Side Cryptographic Security

All hashing and encoding operations use your browser's built-in Web Crypto API and native JavaScript functions. No data is transmitted to any server, making it safe for working with sensitive tokens and credentials.

Hash & Encode Toolkit – Frequently Asked Questions

What is a SHA hash?

A SHA (Secure Hash Algorithm) hash is a fixed-length cryptographic fingerprint of input data. SHA-256 produces a 64-character hex string, SHA-512 produces 128 characters, and SHA-1 produces 40 characters. Hashes are one-way functions — you cannot reverse a hash back to the original input. They are used for verifying data integrity, password storage, and digital signatures.

What is the difference between Base64 and URL encoding?

Base64 encoding converts binary data into ASCII text using A-Z, a-z, 0-9, +, and / characters — commonly used for embedding binary data in JSON or HTML. URL encoding (percent-encoding) replaces unsafe characters with %XX codes — used for passing data in URLs. They serve different purposes and produce different outputs.

Can I verify a JWT signature?

This tool decodes JWT tokens to display the header, payload, and signature sections in readable JSON format. However, it does not verify the cryptographic signature — that requires the secret key used to sign the token. The decoded output is useful for inspecting token contents and checking expiration times.

Why is MD5 not available?

MD5 is considered cryptographically broken and is not supported by the Web Crypto API. We recommend using SHA-256 or SHA-512 for any security-sensitive applications. SHA-1 is also available but is deprecated for security purposes — use it only for legacy compatibility.

Is my data safe when using this tool?

Yes. All hashing, encoding, and decoding operations run entirely in your browser. No data is sent to any server. The Web Crypto API used for SHA hashing is the same security infrastructure used by HTTPS websites. Your sensitive tokens and data never leave your device.

Key Features & Benefits

Cryptographically Secure Passwords

Generate passwords using the Web Crypto API's crypto.getRandomValues(), which provides true cryptographic randomness — the same standard used by professional password managers. No predictable patterns, no pseudorandom shortcuts.

Customizable Password Options

Control password length (8-128 characters), include or exclude uppercase, lowercase, numbers, and symbols. Toggle ambiguous character exclusion (I, l, 1, O, 0, o) to prevent confusion when reading or typing passwords.

Password Strength Meter

See an instant visual strength assessment (Weak, Fair, Strong, Very Strong) based on length, character diversity, and complexity. The progress bar gives you at-a-glance confidence in your generated password.

Multi-Type QR Code Generator

Generate QR codes for Text, URLs, Email addresses, Phone numbers, and WiFi credentials. The WiFi QR type includes network name (SSID), password, and encryption type — scan to auto-connect.

Download QR as PNG

Download your generated QR code as a PNG image file in three sizes (128×128, 256×256, 512×512). Use the downloaded image for printed materials, business cards, or digital sharing.

Password & QR Generator – Frequently Asked Questions

How secure are the generated passwords?

The passwords are generated using crypto.getRandomValues(), which provides cryptographically secure random numbers sourced from your operating system's entropy pool. This is the same method used by professional password managers like Bitwarden and 1Password. A 16-character password with all character types has over 10^30 possible combinations.

What are ambiguous characters?

Ambiguous characters look similar in many fonts and can cause confusion when reading or typing passwords: uppercase I vs lowercase l vs number 1, and uppercase O vs number 0 vs lowercase o. Enable 'Exclude ambiguous characters' to avoid these if you need to type passwords manually.

Are the generated QR codes scannable?

The QR code generator creates a visual representation of your data with finder patterns in the corners. For simple text and URLs, it produces recognizable QR-style codes. For production use or complex data, we recommend using a dedicated QR library for maximum scan reliability across all devices.

How does the WiFi QR code work?

The WiFi QR code encodes your network credentials in the standard WIFI: format. When someone scans it with their phone's camera, they get a prompt to join the network automatically — no manual password entry needed. The SSID, password, and encryption type (WPA/WPA2, WEP, or None) are all encoded.

Are my passwords stored anywhere?

No. Passwords are generated in your browser and displayed on screen only. They are never sent to any server, stored in any database, or cached anywhere. Once you navigate away from the page, the password is gone. We recommend copying and storing it in a password manager.

Key Features & Benefits

Line-by-Line Diff

Compare two texts line by line using the Longest Common Subsequence (LCS) algorithm. Added lines are highlighted in green, deleted lines in red, and unchanged lines appear normally with line numbers for easy reference.

Word-by-Word Diff

Compare texts at the word level to catch smaller changes within lines. This mode highlights individual word additions and deletions, making it ideal for editing and proofreading where line-level comparison is too coarse.

Diff Statistics Summary

See at-a-glance counts of added, deleted, and unchanged lines. The badge-style summary gives you an instant understanding of how much content changed between the two versions.

Swap Texts Instantly

One-click swap button to reverse the original and modified texts. This is useful when you want to see the diff from the opposite perspective — what was removed vs. what was added.

100% Client-Side Comparison

All diff computation runs in your browser using a JavaScript LCS implementation. No text is sent to any server, making it safe for comparing sensitive documents, code, and confidential content.

Diff Checker – Frequently Asked Questions

What algorithm does the diff checker use?

The diff checker uses the Longest Common Subsequence (LCS) algorithm to identify the longest matching sequence between two texts. This produces an optimal diff that shows the minimum set of changes needed to transform the original text into the modified text. It's the same fundamental approach used by Git's diff command.

What is the difference between line-by-line and word-by-word diff?

Line-by-line diff treats each line as a unit — if any part of a line changes, the entire line is marked as changed. Word-by-word diff breaks text into words and shows exactly which words were added or removed within a line. Use line diff for structural changes and word diff for detailed editing.

Can I compare very large texts?

The LCS algorithm has O(m×n) time complexity, where m and n are the number of lines or words. For texts up to several thousand lines, the comparison is instant. For very large files (tens of thousands of lines), there may be a brief delay but the tool will still work.

Is my text stored or sent anywhere?

No. All comparison logic runs entirely in your browser using JavaScript. Your text is never sent to any server, stored in any database, or accessible to anyone else. This makes it safe for comparing sensitive documents, confidential code, or private content.

What do the + and − symbols mean in the diff result?

The + symbol marks lines or words that exist in the modified text but not in the original (additions). The − symbol marks content that exists in the original but not in the modified text (deletions). Lines without a symbol are unchanged and appear in both versions.

Dev Tools Lab

Key Features & Benefits

One-Click JSON Formatting

Validation with Error Messages

Minify JSON for Production

Interactive Tree View

JSON Statistics

Copy & Clear with One Click

JSON Formatter – Frequently Asked Questions

Key Features & Benefits

Real-Time Regex Matching

Capture Group Visualization

5 Regex Flags Support

Common Pattern Presets

Interactive Quick Reference

Instant Error Feedback

Regex Tester – Frequently Asked Questions

Key Features & Benefits

SHA Hash Generation

Base64, URL & HTML Encoding

JWT Token Decoder

Copy Results Instantly

Browser-Side Cryptographic Security

Hash & Encode Toolkit – Frequently Asked Questions

Key Features & Benefits

Cryptographically Secure Passwords

Customizable Password Options

Password Strength Meter

Multi-Type QR Code Generator

Download QR as PNG

Password & QR Generator – Frequently Asked Questions

Key Features & Benefits

Line-by-Line Diff

Word-by-Word Diff

Diff Statistics Summary

Swap Texts Instantly

100% Client-Side Comparison

Diff Checker – Frequently Asked Questions

Dev Tools Lab – Frequently Asked Questions