I used nothing but free web tools. And it seems to work.

I couldn't find a simple portfolio performance tool on the web, where I could just paste cash inflows, outflows and current value of my portfolio and get the portfolio performance calculated. Everything I found was in some way cumbersome and cluttered with ads.

I used Perplexity for the coding and Codeberg for the hosting.

I verified the output manually for some examples and all seems fine. Maybe it is useful for others too. If anyone can spot a problem in this small project, I would be very grateful to hear about it.