User-Generated Non-Custodial Bitcoin Wallets (Users Manage Their Own Keys)
Bitnob provides Bitcoin blockchain infrastructure for businesses that want to build fully non-custodial wallets.
In this model:
Users generate and control their own private keys.
All transaction signing happens on user devices.
Bitnob provides address monitoring, transaction broadcasting, fee estimation, and blockchain queries.
Bitnob never touches private keys, unsigned transactions, or funds.
Core Concepts
| Concept | Description |
|---|---|
| Self-Custody | Users fully control their wallets and private keys. |
| Bitnob’s Role | Backend Bitcoin infrastructure (broadcasting, fee estimation, monitoring). No keys. No custody. |
| Signing Transactions | Must happen locally on the user’s device. |
| Address Types Supported | Legacy (P2PKH), Nested SegWit (P2SH), Native SegWit (P2WPKH), Taproot (P2TR). |
Developer Responsibilities
Generate Bitcoin wallets securely (BIP32, BIP39, BIP44 recommended).
Build full key management and signing flows into your app.
Query balances, broadcast transactions, and monitor addresses using Bitnob APIs.
Never send private keys or seed phrases over the network.
Recommended Development Tools
You can use established open-source Bitcoin developer toolkits such as:
| Tool | Description |
|---|---|
| BDK (Bitcoin Development Kit) | A modern, production-grade toolkit for building Bitcoin wallets, developed by Spiral (backed by Block, Inc.). Supports key generation, descriptor wallets, transaction building and signing. |
| bitcoinjs-lib (JavaScript) | Lightweight Bitcoin library for address derivation, transaction signing, etc. |
| Noble Bitcoin Libraries (JavaScript) | Simple and audited libraries for Bitcoin cryptography. |
| btcd / lnd libraries (Go) | For backend-heavy Bitcoin apps (more advanced). |
You can integrate BDK easily with Bitnob as your backend broadcast and monitoring layer.
BDK supports languages like:
Rust (core)
Swift (iOS apps)
Kotlin (Android apps)
Key APIs Provided by Bitnob
| Action | Method | Endpoint |
|---|---|---|
| Watch address | POST | /api/v1/noncustodial/bitcoin/address/watch |
| Watch multiple addresses | POST | /api/v1/noncustodial/bitcoin/address/watch/bulk |
| Broadcast signed transaction | POST | /api/v1/noncustodial/bitcoin/transaction/broadcast |
| Batch broadcast transactions | POST | /api/v1/noncustodial/bitcoin/transaction/batch/broadcast |
| Estimate fees | GET | /api/v1/noncustodial/bitcoin/fees/estimate |
| Fetch address balance | GET | /api/v1/noncustodial/bitcoin/address/balance |
| Fetch address transactions | GET | /api/v1/noncustodial/bitcoin/address/transactions |
Putting It All Together
This section walks through how you can build a real Bitcoin non-custodial wallet using Bitnob RPCs.
Step 1: Wallet Generation (Onboarding New User)
Use BDK (or bitcoinjs-lib) on the client device.
Generate a new BIP39 seed phrase.
Derive master private and public keys.
Generate the first Bitcoin address (SegWit or Taproot recommended).
Offer the user a backup flow for the seed phrase.
Example: Mobile app using BDK-Swift (iOS) or BDK-Kotlin (Android). Bitcoin address displayed as QR code.
Step 2: Display Wallet Dashboard
Query address balances using Bitnob API.
Display recent transaction history from Bitnob.
Update balances automatically via webhook listening or scheduled polling.
Step 3: Receiving Bitcoin
Show fresh address (or rotate automatically after each payment).
Monitor address with Bitnob's webhook service.
Detect inbound payments and confirmations.
Step 4: Sending Bitcoin
Fetch UTXOs if needed.
Use BDK or bitcoinjs-lib to build a transaction (inputs, outputs).
Estimate fees dynamically with Bitnob's fee API.
Sign transaction locally using the user's private key.
Push signed transaction to Bitnob /transaction/broadcast.
Step 5: Wallet Operations
Periodically rotate addresses to preserve privacy.
Allow users to label transactions internally.
Show mempool status for pending transactions.
Support Replace-By-Fee (RBF) for speeding up transactions later (optional advanced feature).
Real-World Sample Implementation Outline
| Component | Tools/Libraries | Purpose |
|---|---|---|
| Key Generation | BDK (Swift, Kotlin, Rust) / bitcoinjs-lib | Secure private key and address generation |
| Transaction Building | BDK, bitcoinjs-lib | Assemble and sign transactions on device |
| Blockchain Interface | Bitnob APIs | Fetch balances, broadcast transactions, monitor addresses |
| Webhooks | Bitnob Webhooks | Real-time transaction notifications |
| Backup & Recovery | Manual seed backup, optional cloud backup (encrypted) | Protect against device loss |
Key Benefits of This Model
You control the user experience 100%.
Your users retain their privacy and custody.
You avoid needing to run and maintain Bitcoin full nodes.
You can scale globally with minimal blockchain overhead.
You are ready for advanced Bitcoin features like Taproot, Schnorr signatures, and Miniscript when needed.
Example Full System Flow Diagram
Use BDK or similar libraries for secure wallet building — avoid reinventing cryptography.
Use Bitnob purely for node-level services — blockchain broadcast, monitoring, fee suggestion.
Prioritize user education on backups, security, and transaction confirmations.
Building non-custodial wallets is challenging — but with Bitnob's backend + open-source Bitcoin SDKs like BDK , it becomes achievable even for small teams.
