About

Dougudana ("tool shelf" in Japanese) is a small shelf of single-purpose web tools, built on three principles:

• Everything runs in your browser — your input never leaves your device. The tools even work offline once loaded.
• Free, no sign-up — open, use, close.
• Explained mechanics — every tool comes with a note on how it computes its result, because a tool you can't understand is a tool you can't trust.

Operator

The site is run by an individual. Tools are added and improved continuously, with AI assistance (Claude) used in development. Logic and documentation are human-reviewed before release.

Accuracy

We take accuracy seriously, but always verify against primary sources for anything important. Found a bug? Please tell us via the contact page.