Developer Utilities,
Without the Context Switch
Decode JWTs, encode Base64, convert CSV, test regex, generate UUIDs — all in your browser, all free, all instant. No Postman, no terminal, no sign-up.
5 Tools for Everyday Dev Work
Each tool covers a specific, recurring developer task. No tab-switching, no installs, no rate limits.
JWT Decoder
Decode and inspect JSON Web Tokens instantly. View the header, payload, and signature in a readable format. Verify token structure without leaving your browser.
Base64 Encode/Decode
Encode any text or data to Base64 format, or decode Base64 strings back to readable text — essential for HTTP headers, API authentication, and binary data handling.
CSV to JSON
Convert CSV files or pasted CSV data to clean, properly structured JSON. Auto-detects column headers and maps rows to JSON objects. Great for data migration and API prep work.
Regex Tester
Test and debug regular expressions in real time. See all matches highlighted in your test string, inspect capture groups, and toggle flags (i, g, m) instantly.
UUID Generator
Generate cryptographically random UUID v4 strings — one at a time or in bulk. Essential for database primary keys, session tokens, and unique identifiers in any application.
Zero Setup
No npm install, no Docker, no config files. Open the URL, start working. All tools run instantly without any environment setup.
Privacy-First
Your JWTs, CSV data, and regex patterns never leave your browser. Everything processes locally — no server, no logs, no exposure.
Offline Capable
Once loaded, most tools work even when you're offline or on a restricted corporate network. Great for working on trains or in secure environments.
More Tools You Might Need
These tools are in other categories but are frequently used alongside developer work.
Frequently Asked Questions
Is it safe to paste JWTs into the decoder? ↓
The decoding itself is safe: it happens entirely in your browser with JavaScript, and the token is never sent to our servers. The real risk is your surroundings rather than the tool — a production token in your clipboard is still a live credential, so avoid decoding one on a shared or screen-shared machine, and rotate it if you are unsure who saw it.
What is the difference between encoding and encrypting Base64? ↓
Base64 is encoding, not encryption. It converts binary data into a safe ASCII string so it can travel through systems that expect text, such as HTTP headers or data URIs. It provides no security whatsoever, because anyone can decode it without a key. Never use Base64 to hide a password, an API key, or anything else that needs to stay secret.
Why does my regex work in JavaScript but fail in Python? ↓
Regex is a family of dialects rather than one standard. This tester runs the ECMAScript engine that JavaScript uses, while Python, PCRE, and .NET differ in how they handle lookbehind, named group syntax, and certain flags. A pattern that relies on those features can behave differently or fail outright when moved between languages.
Are UUID v4 values truly unique? ↓
They are not guaranteed unique in a mathematical sense, but the odds make it irrelevant in practice. A v4 UUID draws 122 random bits, putting the chance of collision somewhere around 1 in 5.3×10³⁶. This generator uses the browser's Web Crypto API via crypto.randomUUID(), so the randomness comes from a cryptographic source rather than Math.random().
Do these tools work without an internet connection? ↓
Once a page has loaded, the tools on it keep working offline, because the processing is done by JavaScript already sitting in your browser. Reloading the page or navigating to a different tool does require a connection to fetch it.
Why use these instead of command-line tools? ↓
For anything scripted or repeated, a CLI is the better answer. These pages are aimed at the one-off case — checking what is inside a token someone sent you, sanity-checking a pattern before committing it, or converting a file on a machine where you cannot install anything. No setup, and nothing left behind afterwards.
About This Tool
These are the small jobs that interrupt real work: checking what is inside a token someone sent you, confirming a regex before committing it, converting a CSV a client emailed. Each of these is faster in a CLI if you do it daily, and considerably slower if you do it twice a year — which is what this collection is for.
Every tool in this group runs in your browser, so tokens, payloads, and files stay on your machine. That matters most for the JWT decoder, where the thing you are inspecting is often a live credential. For details on analytics and third-party ad requests, see our Privacy Policy.