Free Developer Tools - Instant, No Login Required
These six developer tools cover the tasks that web developers, backend engineers, and DevOps engineers reach for constantly throughout the working day. Every tool runs entirely in your browser - nothing is sent to a server, results are instant, and the tools work offline once the page has loaded. No account, no API key, no extension - just open and use.
JSON Formatter & Validator
JSON is the universal data interchange format for APIs, configuration files, and data storage, but minified JSON is nearly impossible to read. The JSON Formatter takes a JSON string in any state - minified, partially formatted, or with inconsistent indentation - and outputs cleanly formatted JSON with consistent indentation (2 or 4 spaces, configurable). It also validates the JSON syntax and pinpoints any errors with the line and character position. The reverse operation (minification) removes all whitespace to produce the smallest possible JSON string for production use or HTTP transmission. Useful for inspecting API responses, debugging configuration files, and reviewing data exports.
Base64 Encoder / Decoder
Base64 is an encoding scheme that converts binary data into ASCII text, making it safe to transmit through text-based protocols (HTTP headers, JSON, XML, email). Common uses include encoding images for CSS data URIs, encoding credentials in HTTP Basic Authentication headers, encoding binary data in JSON payloads, and working with email attachment encoding. The Base64 Encoder/Decoder handles text encoding in both directions - paste text to encode it, paste Base64 to decode it. Supports the standard Base64 alphabet and the URL-safe variant (+ and / replaced with - and _) used in JWT tokens and URL parameters.
Password Generator
The Password Generator creates cryptographically random passwords using your browser's built-in window.crypto.getRandomValues() API - the same random number generator used for cryptographic operations. This is significantly more secure than pseudo-random number generators. Configure the password length (8-128 characters) and include or exclude uppercase letters, lowercase letters, numbers, and symbols to meet specific password policy requirements. Because the generation happens in your browser, the generated password is never transmitted over the network - only you see it. Generate multiple passwords at once and copy the one you want.
URL Encoder / Decoder
URLs can only contain a limited set of ASCII characters. Special characters (spaces, &, =, ?, #, /, non-ASCII characters) must be "percent-encoded" - replaced with a % followed by two hex digits representing the character's UTF-8 byte value. The URL Encoder converts a string to a safe URL component by encoding all special characters. The URL Decoder reverses this, converting percent-encoded strings back to human-readable text. Useful for constructing API query strings, debugging URL parameters, encoding user-generated content for URL embedding, and reading encoded URLs in server logs or analytics.
Hash Generator
Hash functions produce a fixed-length fingerprint from any input. The same input always produces the same hash; any change to the input produces a completely different hash. The Hash Generator supports MD5 (128-bit, 32 hex characters - fast but cryptographically broken, still useful for file integrity checks), SHA-1 (160-bit, 40 hex characters - also broken for security, still widely used in git commit IDs), SHA-256 (256-bit, 64 hex characters - the current standard for secure hashing), and SHA-512 (512-bit, 128 hex characters - maximum strength). Common uses: verifying file integrity, checking if a password matches a stored hash, generating checksums, and creating deterministic IDs from content.
JWT Decoder
JSON Web Tokens (JWTs) are the standard authentication token format for modern APIs and Single Sign-On systems. A JWT consists of three Base64url-encoded parts separated by dots: the header (algorithm and token type), the payload (claims - user ID, roles, expiration time, etc.), and the signature. The JWT Decoder splits a token and decodes the header and payload sections so you can read the claims - the user ID, expiration timestamp, issuer, audience, and any custom claims the API includes. This is invaluable for debugging authentication issues, checking whether a token has expired, and understanding what data is stored inside a token. Note: the decoder does not verify the signature - use server-side verification for security-critical checks.
Frequently Asked Questions
Are these developer tools free and unlimited?
Yes, completely free and unlimited. There are no usage limits, no rate limiting, no API key required, and no account needed. All six tools - JSON Formatter, Base64 Encoder, Password Generator, URL Encoder, Hash Generator, and JWT Decoder - are available to everyone at no cost. There is no premium tier or paid plan. The tools run in your browser, so there are no server costs tied to your usage that would require payment.
Is it safe to paste sensitive data (passwords, tokens, API keys) into these tools?
Yes. All processing happens locally in your browser - nothing you paste into these tools is transmitted to any server. When you paste a JWT token into the JWT Decoder, or text into the Hash Generator, or a password into the Base64 encoder, that data stays in your browser's JavaScript environment and never leaves your device. We cannot see what you paste and do not log any input. However, always exercise caution with truly sensitive data: check the browser console, use browser DevTools to verify no network requests are made, and consider using an offline environment for the most sensitive operations.
Which hash algorithm should I use?
For security-sensitive purposes (password storage, digital signatures, data authentication): use SHA-256 or SHA-512. MD5 and SHA-1 are cryptographically broken - collisions can be generated, meaning two different inputs can produce the same hash - so they must not be used for security. For non-security purposes (file integrity verification, cache keys, deduplication identifiers): MD5 is perfectly adequate and faster. Git uses SHA-1 for commit hashes. Blockchain systems typically use SHA-256. For general-purpose secure hashing in 2024+, SHA-256 is the standard recommendation.
How do I decode a JWT token and check if it has expired?
Paste the full JWT (the three dot-separated parts) into the JWT Decoder. The decoder splits the token and displays the payload claims in readable JSON. Look for the exp claim - this is the expiration time as a Unix timestamp (seconds since January 1, 1970). The decoder automatically converts this to a human-readable date and compares it to the current time, clearly showing whether the token has expired. Also check the iat (issued at) and nbf (not before) claims if present to understand the token's full validity window.
What is the difference between URL encoding and Base64 encoding?
These are different encodings for different purposes. URL encoding (percent-encoding) is used to safely include special characters in URLs and query strings - a space becomes %20, an ampersand becomes %26. It is designed for URL contexts only. Base64 encoding converts binary data to a text string using 64 safe ASCII characters - it is used for transmitting binary data through text-based channels (email, JSON, HTTP headers). URL encoding makes a string URL-safe. Base64 encoding makes binary data text-safe. A URL-encoded string is still recognisably similar to the original; a Base64-encoded string looks like a completely different block of text.