epanet-js is a new web application that combines modern web maps with the industry-standard EPANET hydraulic simulation algorithm. It’s for people planning and updating water utility systems: connecting pipes and pressures and figuring out what will happen. It’s a problem area that I’m totally fascinated by and know very little about. It’s made by the folks from Iterating - Luke Butler and Sam Payá, who are experts in the field.

If you’ve been following along with my blog and projects, you might notice something familiar about this screenshot of epanet-js:

Yep! A lifetime ago, I built a company and product called Placemark, which was a tool for creating and editing map data. When the business part didn’t work out, I published a free-to-use version of Placemark and made the code open source. I chose a very permissive license for the code: the MIT license. I wanted to let anything happen, including - especially - people creating paid products with the code.

It’s hard to explain to people outside of the world of open source that folks building a business with the help of my code is the dream.

Partly it’s that ‘being helpful’ is one of the goals in life that never gets old. The other part is that most software becomes obsolete and abandoned quickly. Creating software with any legacy is rare and something to celebrate.

Plus, Placemark was a general purpose tool in search of a successful niche: I never figured out what that niche was. I had a lot of learning to do about product-market-fit. But hydraulic simulation is a real market, and these folks are real experts.

There are other markets like this, I’m sure, and using Placemark code as a base could be a good way to jumpstart those companies - it’s not perfect, as I’ve documented extensively, but it could be good as a first step.

And the folks at Iterating have even contributed changes upstream to the open source Placemark codebase, but that isn’t required by the MIT license at all: that’s just because they’re cool folks.

They’ve also open sourced the core epanet-js library, and released the web application under the Functional Source License, which makes new code contributions open source after two years.

And epanet-js is a tool that you can run in a browser - full simulations with a WASM-based engine. It’s competing with expensive old-school software that costs $16,000 a year, runs exclusively on Windows, is priced by “pipes”, and uses the same engine, EPANET. This is so much better in comparison. A radical improvement.

Congrats to Luke and Sam for creating epanet-js. It’s super cool. If you speak hydraulic simulation or know someone who does, try it out!