Free Developer Tools That Run in Your Browser

Tools that do not ask you to trust them

Most online developer utilities work the same way: you paste your data into a form, it goes to a server you know nothing about, and a result comes back. That is fine for a sample payload and genuinely risky for a production JWT, a query containing customer identifiers, or a log file with session tokens in it.

Layerbit is built the other way round. Every tool here except LayerLink screen sharing is pure client-side JavaScript: the parsing, formatting, validating and converting all happen inside the page already open in your browser. There is no endpoint receiving your input, because there is no endpoint at all.

You do not have to take our word for that, which is the point. Open your browser's developer tools, switch to the Network tab, and use any tool on the site — nothing leaves. Or load a tool, turn off your internet connection, and keep working: it will carry on formatting your JSON quite happily, because nothing it needs is anywhere else.

Built around the details that actually break things

A formatter that only handles clean input is a demo. The interesting work is in the edge cases, so the tools are built for them: the CSV parser is a proper state machine that handles quoted commas, doubled quotes and newlines inside fields; the JWT decoder verifies HMAC and RSA signatures locally with the Web Crypto API rather than just decoding Base64 and calling it validation; the cron generator shows the next five fire times in UTC, because that is the only reliable way to catch the day-of-month/day-of-week OR rule before it hits production.

Each tool is paired with a written guide covering the specification behind it and the ways it goes wrong in practice. Knowing why an unquoted YAML country code turned into a boolean is what stops it happening twice.

Screen sharing without an install

LayerLink is peer-to-peer screen sharing over WebRTC, built for remote support and pair programming without asking anyone to install software or create an account. The video stream travels directly between the two browsers; a signalling service is used only for the initial handshake and never carries video. Sharing a screen requires a desktop browser, since mobile operating systems do not expose screen capture to web pages — but viewing a shared screen works on any modern device.

Free, and honest about why

There is no paid tier, no trial, no account and no upsell. The site is funded by advertising and by the custom engineering work described under Built for You above. We would rather say that plainly than pretend a free toolkit has no business model — and it is worth noting that because the local tools never transmit your input, there is nothing about you for us to collect or sell even if we wanted to.

Frequently asked questions

• Do I need to create an account? No. There is no sign-up anywhere on the site and no plans for one. Every tool works on first visit.
• Is my data stored on your servers? For every tool except LayerLink, your input never reaches a server at all — processing happens entirely in your browser. You can verify this in your browser's Network tab.
• Can I use these for work with confidential data? Technically yes, since nothing is transmitted. Your own organisation's policy on what may be pasted into a web page is the constraint that matters, so check it.
• Are the tools free for commercial use? Yes, with no attribution required. Get in touch if you need something beyond that, such as a copy hosted inside your own network.
• Why did some tools disappear? In September 2026 we removed three utilities that depended on third-party APIs for breach data, URL reputation and IP geolocation — services we did not control and which required sending your input elsewhere. Fewer tools we can fully stand behind is the better trade.