About

Toolify is a free collection of online utilities that run entirely in your browser. We build small, focused tools for the kinds of everyday questions that don't deserve a full app.

Our principles

• Everything runs locally in your browser. We don't send your inputs to a server.
• Each tool ships with its formula, sources, and caveats so you can trust the result.
• We rely on Google AdSense to keep the site free — no subscription, no paywall.
• We track when each tool was last updated and revise it when standards change.

How we build and check our tools

Every calculator starts from a published formula or standard — the WHO and CDC for health metrics, established financial math for loans and interest, and primary references for unit definitions. We state the formula and its assumptions on each page, run the math entirely in your browser, and note the limits of what a single number can tell you. When a standard is revised, we update the affected tools and refresh their review date.

Who runs Toolify

Toolify is built and maintained by Kenichiro.S, an independent developer based in Japan. It is a personal project, not a company — which is exactly why every tool runs in your browser and sends nothing to a server.

I started Toolify because I was tired of hunting for a simple converter or calculator and landing on pages buried under pop-ups, sign-up walls, and trackers. I wanted fast, single-purpose tools that respect your time and your data, and that work in the language you actually think in. Every tool here is one I needed myself at some point, and I deliberately keep the list small so I can maintain each one properly.

You can see more of my work at appdevelopsk.com.

Found a mistake or an edge case we missed? Email us at app.develop.sk@gmail.com — we read every message and correct errors quickly.

This page was last reviewed in June 2026.