B2PIX is a privacy-focused, automated P2P Bitcoin exchange platform that bridges traditional Brazilian banking (PIX) with Bitcoin. Users can buy and sell Bitcoin directly with each other using instant PIX transfers, all while maintaining custody of their funds through smart contracts on the Stacks blockchain.
Watch our demonstration video that showcases how B2Pix works:
- PIX Integration: Instant Brazilian real transfers using PIX payment system.
- Stacks Blockchain: Built on Bitcoin's most advanced layer-2 solution.
- sBTC Support: Trade with synthetic Bitcoin (sBTC) for faster, cheaper transactions.
- Privacy First: Invite-only platform with minimal data collection.
- Fee UX via Bolt: Pay Stacks tx fees in sBTC (Bolt Protocol) for simpler UX.
- PIX API Integration: Server-side integration with bank/PSP PIX APIs for payment verification.
- Embedded Wallet: Built-in non-custodial wallet available in the dApp — users can create a new wallet or import an existing one (seed / mnemonic), with keys stored encrypted in the browser and optional encrypted backup/export.
- Email Notifications: Transactional e-mail alerts (e.g., purchase completed, sale completed, payment confirmed).
- Get Invited: Request an invitation to join the platform
- Connect Wallet: Link your Stacks-compatible wallet
- Setup PIX: Configure your Brazilian bank account
- Trade Bitcoin: Buy or sell Bitcoin with other users
A key UX feature of B2PIX is no dual‑token requirement on Stacks. New users don't need STX to pay transaction fees — they can use a fresh wallet and operate only with sBTC:
- Fees in sBTC: All contract calls can pay network fees in sBTC instead of STX.
- No STX setup friction: Users can acquire sBTC and transact immediately without preloading STX.
- Powered by Bolt Protocol: This is enabled by the Bolt Protocol, which allows Stacks fees to be paid in sBTC.
Bolt Protocol Resources:
Result: simpler onboarding and a Bitcoin‑native UX focused on sBTC.
To make onboarding into the Stacks ecosystem as smooth as possible, B2PIX offers two wallet options:
- Connect External Wallet: Users can connect their preferred Stacks wallet (such as Xverse or Leather) through
@stacks/connect. - Use Embedded Wallet: Alternatively, users can choose the built-in non-custodial wallet that is fully integrated into the dApp.
The embedded wallet is designed to offer a Web2-like experience — allowing users to start trading instantly without installing extensions or leaving the app:
- Instant Onboarding: Create or import a wallet directly in-app (mnemonic/seed).
- Secure Key Storage: Private keys are encrypted and stored locally in the browser, with optional encrypted backup/export.
- Seamless UX: Eliminates friction for first-time users of the Stacks blockchain, while maintaining full self-custody.
Result: a simpler and smoother onboarding experience for new users, bridging familiar Web2 usability with the power and security of Web3 on Stacks.
flowchart TD
subgraph Client
F["@stacks/connect"]
end
subgraph Backend
API["REST API"]
Server["B2PIX Server"]
end
subgraph Protocol["Bolt Protocol"]
BOLT["Bolt Protocol API"]
end
subgraph Chain["Stacks Blockchain"]
Hiro["Hiro API"]
C["Smart Contract"]
end
subgraph Bank["Bank"]
PIX["PIX API/PSP"]
end
F -->|Signed Requests| API
API <--> Server
Server <-->|Submit Tx / Fees in sBTC| BOLT
Server <--> PIX
BOLT --> Hiro
Hiro --> C
- Frontend (Angular): Requires a SIP‑030 Stacks wallet and uses
@stacks/connectfor authentication and transaction signing.- Embedded Wallet Integration:
The frontend includes an in-app key manager for the embedded wallet.
It handles wallet creation, import, encryption, signing, and optional backup/export —
enabling direct communication between the dApp and smart contracts without relying on external extensions.
- Embedded Wallet Integration:
- Backend (Rust): Event‑driven services (orders, escrow, PIX). Communicates with the Bolt Protocol API to interact with the Stacks blockchain and enable fees in sBTC (no STX required).
- PIX Integration: The server communicates with Brazilian PIX APIs (banks/PSPs) to verify incoming payments.
- Signed FrontBack Communications: All requests from the frontend to the backend carry messages signed by the user’s SIP‑030 wallet, providing origin authentication and replay protection.
BUYER BACKEND SELLER
│ │ │
│ │ │
│ │ 0. Create Advertisement │
│ │ │
│ │<───────────────────────────│
│ │ │
│ │ 1. Lock sBTC in │
│ │ Smart Contract (Bolt) │
│ │<───────────────────────────│
│ │ │
│ 2. Request to Buy │ │
│───────────────────────────▶│ │
│ │ │
│ │ 3. Reserve sBTC amount │
│ │ for Buyer in contract │
│ │ │
│ 4. Send BRL via PIX │ │
│ to seller's PIX key │ │
│ │ │
│ 5. Mark as Paid │ │
│───────────────────────────▶│ │
│ │ 6. Verify Payment │
│ │ - Check PIX transaction │
│ │ - Verify amount │
│ │ │
│ │ 7. Update Buy Status │
│ │ PAID PAYMENT_CONFIRMED │
│ │ │
│ │ 8. Notify Seller │
│ │───────────────────────────▶│
│ │ │
│ │ 9. Release sBTC from │
│◀───────────────────────────┤ Smart Contract (Bolt → Stacks)
│ Bitcoin received │ │
│ │ │
Contract Source Code boltproto-sbtc.clar
Contract address — Testnet
ST3QZNX3CGT6V7PE1PBK17FCRK1TP1AT02W1N0YJF.boltproto-sbtc-rc-2-0-0
View on Explorer
Contract address — Mainnet
SP3QZNX3CGT6V7PE1PBK17FCRK1TP1AT02ZHQCMVJ.boltproto-sbtc-v2
View on Explorer
Functions used by B2PIX trade flow
- Lock seller sBTC:
transfer-stacks-to-bolt - Release to buyer:
transfer-bolt-to-stacks
- On-chain truth: Asset custody and state are enforced by Clarity contracts.
- Off-chain signal: PIX "payment received" is verified off-chain (bank app/PSP event).
- Disputes / timeouts: If no valid confirmation before expiry, send refunds to the seller.
B2PIX is designed to be a sustainable, revenue-generating platform while maintaining privacy and accessibility:
-
Transaction Fees
- 0.5%–1% fee on completed trades (split between platform and liquidity providers)
- Fees are only charged on successful transactions, incentivizing quality service
- Competitive with traditional exchanges while offering better privacy
-
Referral Program
- User-driven growth through invitation codes
- Referrers earn a percentage of fees from referred users
- Creates organic, trust-based network effects
-
Strategic Partnerships
- Integration partnerships with Stacks wallet providers (Xverse, Leather, etc.)
- Collaboration with Brazilian fintech companies and PSPs for PIX API access
- White-label solutions for other markets
- Phase 1 (Current): Brazil-focused with PIX integration
- Phase 2: Expansion to other Latin American countries (Mexico's CoDi, Colombia's Transfiya, etc.)
- Phase 3: Global expansion to markets with instant payment systems
- Phase 4: Additional financial products (recurring purchases, DCA, merchant solutions)
- No KYC friction: The invite-only model minimizes regulatory overhead while maintaining compliance
- True self-custody: Users retain full control of their Bitcoin in their own wallets
- Instant settlement: PIX enables real-time fiat transfers (24/7/365)
- Bitcoin-native UX: A single-token experience via the Bolt Protocol simplifies onboarding
B2PIX showcases several cutting-edge features in the Stacks ecosystem:
- Built on Bolt Protocol for sBTC fee payment
- Hybrid wallet architecture combining external wallet support with embedded Web2-like experience
- Server-side PIX verification integrated with smart contract escrow
- SIP-030 message signing for secure frontend-backend communication
This project is licensed under the Apache License 2.0 - see the LICENSE file for details.