Free Online Developer Tools — JSON, QR Codes, Passwords & More

JSON Formatter

Beautify messy JSON with syntax highlighting. Validate JSON structure, minify for production, and spot errors instantly with line numbers.

HTML Beautifier

Beautify minified or messy HTML code with proper indentation. Also minify HTML for production deployment.

Password Generator

Generate cryptographically secure passwords with custom length (8–128 chars), uppercase, lowercase, numbers, and symbols. Includes strength indicator.

QR Code Generator

Generate QR codes for URLs, text, contact info, WiFi, or anything. Customize size and colors. Download as PNG or SVG.

Random Number Generator

Generate single or multiple random numbers between any min and max value. Options for unique numbers, sorting, and copying results.

Regex Tester

Build and test regular expressions in real time. See matches highlighted instantly, inspect capture groups, and debug your patterns — all in your browser, nothing uploaded.

Diff Checker

Paste two pieces of text and instantly see line-by-line differences highlighted — additions in green, removals in red. Powered by an LCS diff algorithm, runs entirely in your browser.

UUID & Hash Generator

Generate cryptographically secure UUID v4 identifiers in bulk, and compute MD5, SHA-1, SHA-256, SHA-384, and SHA-512 hashes of any text — all processed locally in your browser.

Markdown to HTML Converter

Write or paste Markdown and instantly see a live HTML preview plus the generated HTML code — supports headings, bold/italic, links, images, lists, quotes, and code blocks.

Base64 Encoder/Decoder

Convert plain text to Base64 encoding or decode Base64 strings back to readable text — fast, accurate, and processed entirely in your browser.

JWT Decoder

Paste a JWT and instantly view its decoded header, payload, and signature in readable JSON — useful for debugging authentication tokens. Nothing leaves your browser.

CSV to JSON Converter

Paste CSV data with a header row and instantly convert it into a clean, structured JSON array — handles quoted fields and commas correctly, runs in your browser.

What Is JSON and Why Does Every App Use It?

Almost every app on your phone sends and receives information using a format called JSON. Here's what it actually is, explained simply.

What Is Regex (Regular Expressions) and How Does It Actually Work?

Regex looks like a secret code, but it's really just a smart way of describing patterns in text. Here's how it works, explained simply.

What Is Hashing and Why Is It So Important for Security?

Ever wondered how websites store your password without actually 'knowing' it? The answer is hashing — a one-way digital fingerprint.

What Is a UUID and Why Do Computers Need Billions of Unique IDs?

Every order, post, and file on the internet needs its own unique ID — and there is no central office handing them out. So how does it work?

What Is Base64 Encoding? (Explained With Simple Examples)

You've probably seen long strings of random-looking letters in web addresses or code. Many of them are Base64 — here's what it actually does.

What Is a JWT and How Does It Let Websites Remember You're Logged In?

When you log into a website, how does it remember who you are on the next page without asking for your password again? Meet the JWT.