About deftools.io
deftools.io is a collection of 302 free online developer tools. From encoding and formatting to DNS lookups and image processing — every tool runs entirely in your browser. Your data never touches our servers for the core operations.
The site was started as a solo project by a developer who wanted a single place for all the small utilities that developers reach for daily — without ads, without sign-ups, and without data leaving the browser. Every tool is a standalone page, built with vanilla JavaScript and Astro, designed to be fast and reliable.
New tools are added regularly based on real search demand and developer needs. Each one is a standalone page designed to be fast, focused, and useful — no fluff, no sign-ups.
How it works
Each tool is a self-contained HTML page with inline JavaScript. When you visit a tool, the page loads in your browser and all computation happens client-side — there is no backend server processing your data. A few tools make DNS or WHOIS queries to public APIs (see the Privacy Policy for the full list), but your actual input is never stored or transmitted except for those explicitly requested lookups.
The site is deployed on Cloudflare Pages with Workers for the OG image and placeholder image endpoints. There are no databases, no user accounts, and no tracking cookies.
What makes this different
All processing happens in your browser. Files and text you paste stay on your machine.
No accounts, no cookies, no tracking. The site works without JavaScript telemetry.
From base64 encoding to Kubernetes YAML generation — organized into 15 categories.
Static HTML with no framework overhead on the client. Every page loads instantly.
Have a suggestion or found a bug? Reach out at feedback@deftools.io.