Build a Bitcoin transaction by hand — a free interactive walkthrough, with the real Bitcoin Core code behind each step (no signup)

I kept seeing people (myself included) get stuck on how a Bitcoin transaction actually works — "your balance isn't stored anywhere," UTXOs, change, fees, signing. Most explanations are either hand-wavy or a wall of C++. So I built a free page where you do it yourself: tap your balance to see it's really a set of UTXOs, pick which ones to spend, watch the change output appear, drag the fee rate, sign, and watch it get mined into a block. ~10 minutes, no signup, works on mobile. Because this is and not : every step has an optional "show the real Bitcoin code" panel — the actual CTxOut / CTxIn / CheckTxInputs from Bitcoin Core, linked to the source on GitHub — so you can verify it's not an AI hand-wave. The amounts are a teaching example, but the mechanics match mainnet. It's free, I'm not selling anything — built it because I wanted it to exist. Would genuinely appreciate feedback, especially if anything is wrong or confusing: https://visualizingbitcoin.com/