About ecech.
ecech. is a library of small, single-purpose web tools. Each one does exactly one thing, loads as a single self-contained page, and runs entirely inside your browser.
The project started from a simple irritation: most online calculators answer the textbook version of a question rather than the version people actually have. A currency converter that ignores your card's foreign transaction fee is not wrong, but it is not useful either. A margin calculator that ignores marketplace commission will happily tell you a losing product is profitable. We build the version with the awkward parts left in.
How the tools are built
- No server. Your inputs are never transmitted. Calculations run in JavaScript on your device.
- No account. Nothing to sign up for, nothing to cancel.
- Shown working. Every tool prints its formula and states its assumptions.
- Honest limits. Where a result is an estimate, we say so and explain the error bars.
The site is funded by advertising so the tools can stay free. We do not sell data, run affiliate redirects inside calculators, or gate results behind an email form.
Corrections and contact
If a formula looks wrong, it might be. Tell us which tool and what you expected, and it gets fixed. The same address handles questions about privacy, advertising and anything else:
We read everything and reply to anything that needs a reply. There is no support ticket system, no chatbot and no contact form that goes nowhere.