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Privacy-First Developer Tools. Everything Runs Locally. Here is what makes LocalOnly a genuinely different kind of developer toolkit.
LocalOnly bundles 37+ focused developer utilities into a single, fast, consistent app. Unlike most online tools, nothing you paste ever leaves your device. Every feature below is built around one promise: you get powerful tooling without giving up your data. Browse all tools to see the full catalogue.
Every transformation runs locally in your browser using JavaScript and Web Workers. There is no server that receives your input, no upload step, and no round trip to an API. What this means for you:
Privacy is not a setting you toggle here - it is the architecture. There are no accounts, and the content you process is never logged, uploaded, or analysed. It stays in your browser, always.
A broad, growing catalogue covers the tasks you reach for every day:
See the complete, categorised list on the all tools page.
LocalOnly is a Progressive Web App. Install it once and it keeps working with no connection at all - on a plane, behind a firewall, or in a secure environment where external sites are blocked. Because the code is cached locally, launches are instant and reliable.
Heavy work runs off the main thread using Web Workers, so the interface stays responsive while large JSON documents parse, format and validate. Debouncing and virtualization keep scrolling smooth and typing lag-free even on multi-megabyte inputs.
The interface is built to WCAG-AA standards, with full keyboard navigation, sensible focus order, semantic markup and screen-reader support. Read more on the Accessibility page.
Every tool is free, with no paywall, no premium tier and no sign-up. The site is kept running through unobtrusive ads, never by selling or monetising the data you process.