epanet-js
No installs. No forced cloud storage. Just fast, local-first water modeling — powered by the engine you already trust.
You shouldn't have to choose between speed, security, and affordability just to understand your water networks.


Model quickly and securely with local-first file-saving and a faster, smoother interface — all on top of the trusted EPANET engine.
epanet-js works directly with files on your local computer and is cloud-optional. By default, your projects are run and saved locally — giving you full control, security, and privacy.
Choose the cloud only if and when you need it.
epanet-js keeps the core functionality you’re familiar with but adds a smoother, faster experience with modern touches like undo/redo, automatic elevations, quick drawing of elements, and basemaps like satellite view.
Import your network or build from scratch with intuitive tools that make it easy to update, draw, connect, and edit.
Everything you need to work quicker — without having to learn a new tool.

Utilities & consultants
Build fast, run local. Everything you need to just get the job done, none of the feature bloat.
Educators & professors
Teach new modelers the concepts without fighting software. Watch students draw real networks and run sims in minutes — not hours.
Students & new engineers
Focus on learning, not software quirks. Undo/redo, auto-elevation, visual overlays — built to help you learn water modeling quickly.
EPANET was a gift to the industry — free, open-source water modeling for all. But commercial vendors built on it, locked away improvements, and left the community behind.
epanet-js is our answer: a faster, simpler, affordable water modeling tool that protects your privacy and sustains the open-source future of water modeling.
We’re proud to be part of the next chapter — and we’re just getting started.

When you purchase more features in epanet-js, you’re investing in the future of open-source EPANET development.
Our open-source model balances innovation and accessibility:
Anyone can build on our code. The two-year commercial-use delay gives us the incentive to keep pushing forward — and that fuels progress for everyone.
That means when you support us, you support more affordable hydraulic modeling software for the entire community.
Choose the plan that works for you
Individual named license
Floating shared license
Have questions? Send us an email or book a call.
Available for non-commercial projects, learning, and student work.
For curious minds and personal growth.
Free for students and teachers.
Find answers to common questions about epanet-js.

Luke Butler
Co-founder

Sam Payá
Co-founder
You may not know this, but for decades, the U.S. EPA has given the water industry an extraordinary gift: the free and open-source hydraulic modeling software EPANET. Odds are, if you've used any commercial hydraulic modeling software today, it was built on the EPANET engine.
The problem is, instead of giving back to their open-source roots like other industries do, big-name software vendors took EPANET's open code, built private tools on top of the engine, and then locked those improvements behind patents and proprietary licenses.
Some vendors even pressured the EPA to focus only on the engine — discouraging any effort to improve the interface or user experience for everyone else.
Those vendors now charge you exorbitant prices to use their software while EPANET lags behind — and utilities, engineers, and educators with smaller budgets suffer.
We think this is backwards — and we're on a mission to change it. We're focused on creating a better experience for the entire hydraulic modeling community.
That's why we built epanet-js under an FSL license — because we want to give you an affordable, easy-to-use water modeling option that creates a sustainable future for open-source EPANET development.
Support EPANET by using software that supports it back.
Simple, quick, and useful right out of the gate — designed to open-and-go.
Launch epanet-js now