Free Online Developer Tools — All in Your Browser
Format JSON, generate UUIDs, hash text, encode Base64, test regex, and decode JWTs. Every tool runs locally — nothing is sent to a server.
Get Started →All Tools
JSON Formatter
Format, minify, and validate JSON in one place.
UUID Generator
Generate single or batch UUID v4 values.
Hash & HMAC Generator
Generate SHA-1/256/384/512 and MD5 hashes plus keyed HMAC codes.
Base64 Encoder / Decoder
Encode text to Base64 or decode Base64 to text.
URL Encoder & Decoder — Convert Text to URL-Safe Format
Encode text for URLs or decode encoded URL values.
Regex Tester
Test regular expressions with live match highlighting and capture group table.
CRON Parser
Parse CRON expressions, describe them in plain language, and preview the next 10 runs.
JWT Decoder & Verifier
Decode, build, and verify JWT tokens — entirely client-side (HS256).
URL Parser & Query String Decoder
Break any URL into protocol, host, path, query, and hash — UTM-labeled, double-encoding flagged, JSON output.
Query String Builder
Compose URL query strings from key-value rows — repeated keys for arrays, automatic percent-encoding, live preview.
Base Converter
Convert integers between bases 2, 8, 10, and 16.
Binary Text Converter
Convert plain text and binary bytes in both directions.
Hex Text Converter
Convert text to hex bytes and decode hex to text.
Every tool runs in your browser. API keys, tokens, and sensitive data never touch a server.
Open any developer tool and start immediately. No extension, no CLI, no setup required.
Every tool is free with no limits, no premium tier, and no usage cap.
No sign-up, no email, no tracking. Just the tool you need, right now.
Frequently Asked Questions
Are my API keys or tokens safe when I use these tools?
Yes. All processing happens entirely in your browser. JWT tokens, API keys, and any other sensitive values you paste are never transmitted over the network.
Do I need to install anything?
No installation is required. Every developer tool runs directly in your browser without extensions, plugins, or local dependencies.
What JSON formatting options are available?
The JSON Formatter supports pretty-printing with configurable indentation, minification to a single line, and syntax validation with detailed error messages for invalid JSON.
What UUID version does the UUID generator produce?
The UUID Generator produces version 4 UUIDs using cryptographically secure random numbers from the browser's Web Crypto API.
Which hash algorithms are supported?
The Hash Generator supports SHA-1, SHA-256, SHA-384, SHA-512, and MD5, plus keyed HMAC modes (HMAC-SHA1, HMAC-SHA256, HMAC-SHA512). SHA family hashing uses the browser's built-in Web Crypto API; MD5 uses a pure-JS implementation.
Can I use these tools offline?
Yes. Once the page has loaded, all developer tools work without an internet connection because all processing runs in your browser.
What is Base64 encoding used for?
Base64 encodes binary data as printable ASCII characters. It is used in email attachments, embedding images in CSS or HTML, and encoding API credentials or configuration values.
How do I decode a JWT token?
Paste the JWT into the JWT Decoder and the header, payload, and signature are shown separately. The tool also displays the expiry time and whether the token is currently valid based on its timestamps.
How to format and validate JSON online
Open the JSON Formatter, paste your JSON payload, and the tool automatically formats it with proper indentation and syntax highlighting. If the JSON contains errors, the exact position and reason are shown so you can fix them quickly.
How to generate a UUID online
Open the UUID Generator and click Generate. A cryptographically random UUID v4 appears immediately. For batch generation, specify the count and download all values as a text file or copy them to the clipboard.
How to decode and verify a JWT token
Paste a JWT into the JWT Decoder. The header and payload are decoded and displayed as formatted JSON, and the expiry time is shown in readable form. To verify the signature, switch to the Verify tab and supply the HS256 secret — the tool checks the HMAC-SHA256 signature locally. RS256 and ES256 tokens decode but verification needs server-side public-key checks.
How to generate SHA-256, MD5, and HMAC codes
Open the Hash & HMAC Generator. In Hash mode, every supported digest (SHA-1, SHA-256, SHA-384, SHA-512, MD5) is computed live as you type. Switch to HMAC mode to add a secret key and produce keyed authentication codes (HMAC-SHA1/256/512) — useful for verifying webhook signatures, signing API requests, or any flow that needs more than a plain hash.
How to test a regex pattern interactively
Open the Regex Tester, paste your sample text, and type a pattern with optional flags (i, g, m, s, u). Every match is highlighted in real time and shown as a numbered list with capture groups. Use this to debug a pattern before pasting it into your codebase — much faster than the edit-save-run cycle.
How to translate between text and binary, hex, or Base64
For binary representations, use the Binary <-> Text and Hex <-> Text tools — handy for low-level encoding work, embedded protocols, and reverse-engineering data formats. For ASCII-safe encoding of binary data, use Base64 Tool which supports both standard and URL-safe (Base64url) alphabets.