The chain is the record
Bitcoin is not a dashboard. It's a ledger — consulted, not lived in. Qart uses it to make real commerce events worth recording.
Bitcoin Back
Keep the change. Literally.
You buy a $4.25 coffee, pay with a five. Instead of coins clinking into your pocket, your change comes back as bitcoin — straight to a wallet, no account, no app store, no minimum.
For customers
Change you'd lose in the couch becomes satoshis you actually own. No decision required — just say yes at the register.
For merchants
The change was always coming out of the drawer. It just leaves as bitcoin instead of metal. You keep the cash.
Pay cash
Customer pays as usual.
One tap
"Want your change as bitcoin?" — yes or no.
Show a QR
Customer scans their wallet, or we spin one up on the spot.
Done
Sats land in their wallet. The till keeps the coins. Receipt shows what they received.
The cap is the feature
Bitcoin Back has a maximum — up to $10 in change, that's it. Small enough to be unambiguously change, not a financial service.
The cap isn't a wall we apologize for. It's the guardrail that makes the whole thing legible and safe — to a city official, a small-business owner, and a first-time customer alike.
The city-wide unlock
One shop doing this is a gimmick. A hundred shops turns a downtown into a distributed, opt-in faucet — funded by change people were going to forfeit anyway.
merchant decals — print and post
window cling — white
window cling — orange
Counter cards and circular sticker dots also in the set.
Merchants — say yes in three steps
1
Enable in POS settings
One toggle in your organization settings. Set your own cap or use the default.
2
Put up the decal
A window decal signals your shop is part of the network. Printable from your dashboard.
3
The register does the rest
Your cashier sees a prompt on qualifying cash sales. One tap if the customer wants it, skip if not.
Target: one block, 3–5 merchants, 4 weeks.
Receipts
The receipt is the transaction.
Every BSV transaction is three things at once: the invoice, the payment, and the proof. No reconciliation step. No separate receipt PDF. The txid is the shared anchor.
This isn't a feature Qart built — it's what a shared ledger does. Merchants who use Qart get Enron-proof bookkeeping by default, not because they configured anything.
Triple-entry accounting — Grigg, 2005
For builders
Keys, scripts, ordinals, signed metadata.
The interactive demo walks through the full BSV primitive stack — mnemonic derivation, watch-only xpub addresses, custom scripts, 1Sat ordinal envelopes, and MAP + AIP signed metadata. Driven by the local bsv-ex library.
Keys
Mnemonic → seed → account xprv → xpub. Derive receive addresses without exposing spend authority.
Scripts
Compose script chunks directly. Carry local state and still end in a spendable checksig path.
1Sat Ordinals
Spendable 1-sat P2PKH outputs with inscription envelopes. On-chain digital objects.
MAP + AIP
Structured metadata and identity attestation over the output script. Signed locally, verified anywhere.