I built a free crypto cost basis calculator — here's why (and why it's free)
I kept doing something dumb with my crypto: buying BTC and ETH at a bunch of different prices across a couple of exchanges, and having genuinely no idea what my real average cost per coin was.
"Am I even in profit right now?" is a question I couldn't answer without pulling up a spreadsheet and doing math I didn't want to do. And the tools that do this well are all locked behind accounts, uploads, and subscriptions.
So I built [CostBasis Calc] — a free, no-account calculator that does one thing: you type in your buys (coin, amount, price), it instantly shows your average cost basis per coin and total invested. Add a sell, and you get realized gain/loss and a Form 8949-style report you can export as CSV.
No account. No upload. Nothing leaves the browser. A cost-basis check shouldn't require giving anyone your exchange history. Everything runs client-side — that's the whole trust story, and I put it front and center on the page.
It's a report aid, not a tax filing. I'm not a tax professional, and the tool doesn't pretend to be one. It's clearly labeled: this is a calculator to help you see where you stand — not a substitute for advice, and not filed on your behalf. I'd rather be honest and useful than overclaim and mislead people about their taxes.
