Show HN: I built a simulator for personal finance

I couldn't find a good financial planning tool that felt modern, nuanced, and actually fun to use... and I ended up spending all my free time this past year building one: ProjectionLab

https://projectionlab.com

It doesn't involve linking your financial accounts, you don't have to make an account to try it, the free version has a lot of features, and there's a sandbox mode if you just want to see how the interface works.

Last year I posted a prototype here (back when it was called ProjectiFi): https://news.ycombinator.com/item?id=27844194, and the early feedback from the HN community was extremely helpful! I've put in about 1,000 more hours of dev time on nights/weekends since then, and it's pretty much a whole new app. Here are just a few of the things you can do with it, many inspired by the HN commentary:

- Build detailed and flexible plans for your future that go beyond the standard online retirement calculators

- Backtest on historical data and run Monte Carlo simulations

- Model international scenarios with various account types and tax estimation presets

- Experiment rapidly: the simulation engine runs in your browser and doesn't need to send your data server-side

- Control how/where your data is stored: cloud sync, localStorage only, or manual import/export, (client-side by default, no persistence in the free tier)

- Plan for goals like achieving financial independence, taking time off for travel, home ownership, starting a rental empire, etc.

- Create granular models for how accounts/income/expenses/inflation/etc change over time using interactive plots

- Build dynamic configurations using milestones that support multiple criteria and conditional logic

- Create custom plots to visualize the metrics you care about

- Plan separately or as a couple

- Create and manage client accounts with the Pro version

- Track progress over time and see it overlaid on top of your projections

- Cross-compare between different plans, or stage + analyze multiple changes within a plan (and revert if desired)

- Choose your own icons to personalize things

- And a lot more; for a full breakdown of everything that's new, see the version history

If you feel like checking it out, I would love to hear what you think! Most of the functionality is free (minus data persistence), but for anyone interested in upgrading to Premium, you can use coupon code "HN-10" for 10% off any plan :)

Thanks! I've put a ton of work in since then, and it's been a fun side project that kept me focused and energized and thinking positive thoughts during the pandemic. Also, the fact you remember it as "ProjectFi" is one of the many reasons for the rebrand -- that first "i" in ProjectiFi got lost by so many people.

Well, I must admit there is a graveyard of 60 or so other projects over the years before making anything worth posting here. The dream would be to find a way to work on ProjectionLab full-time, but so far I'm preferring the side-project/bootstrap route focused on growing it slowly and sustainably, in contrast to the VC "unicorn or bust" mentality.

Lovely interface. What does your tech stack look like?

Definitely, the web design and UI immediately grabbed my attention.