The person behind Toolbit
Toolbit is a personal project by Javier Vallejo, a software developer. It started from a simple, specific need: having fast, trustworthy technical calculators on hand — subnetting, VLSM, base conversion, password generation, cron parsing, JSON formatting — without having to create an account, hit an arbitrary usage limit, or wonder where the data typed into a form actually goes.
Why it exists
Plenty of equivalent tools online are buried under intrusive ads, gate basic functionality behind sign-up, or quietly process input on a server without saying so. Toolbit was built with the opposite approach: every calculation runs in the visitor's own browser, the code stays simple enough to verify, and the site is funded through non-intrusive advertising rather than user data or subscriptions.
How it's built
The site is a Next.js app deployed on Render, statically generated, with no backend receiving what gets typed into a tool. Each calculator follows public, verifiable technical specifications — IP addressing RFCs, the standard entropy formula, the cron expression spec — rather than reinventing the logic from scratch.
What's next
The tool catalog keeps growing. If something useful is missing, or if anything on the site isn't working the way it should, the best way to say so is through the contact page.