Introducing epanet-js¶
Fast, local-first water modeling right in your browser
For decades, the U.S. EPA’s EPANET engine has powered almost every hydraulic modeling tool on the market. Yet most of us still wrestle with either the “classic” Windows interface — slow, dated, and held together by workarounds. Meanwhile, commercial platforms cost a fortune, lock up our data, and bury us in features we don’t need.
You deserve better.
The EPANET you know — but modern and enhanced¶
epanet-js brings the EPANET you already trust straight into your browser — no installs, no forced cloud, and no compromises on privacy or speed. Open a tab, start drawing your network or drop in an .inp file, and run simulations in seconds.
We designed epanet-js to feel familiar yet fundamentally better. It's built on the same trusted EPANET engine, but we’ve wrapped it in a smoother, faster interface with the modern features you actually need to get your work done. A core part of this is our local-first philosophy. Your privacy and security are paramount, so epanet-js works directly with files on your local computer. Your projects are run and saved on your machine by default, giving you full control. The cloud is an option if you need it, not a requirement.
Our goal was to build a tool for working, not for troubleshooting. You can draw your network visually, clicking to add nodes and pipes while the software handles details like auto-junctions and automatic elevations. We’ve finally brought essential features like undo/redo to the EPANET workflow, and you can sketch and analyze your networks against real-world layouts using satellite map overlays. Running a simulation is as quick as hitting the keyboard shortcut Shift + Enter. Pressure, flow, and velocity results are visualized on the map — clean, color-coded, and easy to interpret without overwhelming you with options.
Why we're doing this¶
Instead of improving the tools everyone depends on, progress stalled — and utilities, educators, and engineers with smaller budgets suffered. EPANET was a gift to our industry. But over the years, we watched commercial vendors take its open-source code, build proprietary tools, and lock away improvements behind expensive licenses. The community was left behind.
That’s backwards — and epanet-js is our answer.
We're building an affordable, easy-to-use tool that protects your privacy and helps create a sustainable future for open-source development. When you support epanet-js, you're supporting EPANET itself. We use a Functional Source License (FSL) that keeps our code public from day one and makes it fully open-source (MIT) after two years. This model allows us to innovate while ensuring the entire community benefits in the long run.
Ready to see for yourself?