One Wallet. Three Networks. Your Keys.

BTCBitByBit is a Bitcoin education app — and at the heart of it is a self-custody wallet that handles Lightning, Liquid, and on-chain from a single balance. Keys are generated and stored on your device. Never on our servers. Whether you're a parent exploring Bitcoin for the first time or a Bitcoiner who expects BOLT12 and Liquid support, the wallet is built for you.

Why We Built a Wallet

BTCBitByBit is a Bitcoin education app — and at the heart of it is a self-custody wallet that we are genuinely proud of. Lightning, Liquid, and on-chain from one balance. Keys on your device. Send to any address, receive from any wallet, and never think about which network is doing what. Every user gets one the moment they open the app, including on the free tier.

The wallet is what brings the whole app to life. Learn & Earn pays you sats for passing quizzes — those sats land in your wallet. Family Corner lets kids earn sats from chores — straight to their own wallet. Sats-back credits Bitcoin to your wallet every month. Everything you do in the app comes back to the same place: a wallet you own and control.

And because it powers everything, it had to work for everyone. A child on their first day: open the app, earn sats, see a balance. No channel management, no submarine swap prompts, no "waiting for inbound liquidity." A parent who already holds Bitcoin: BOLT12 support, Liquid addresses, on-chain sends, self-custody with keys on device. One wallet for both — approachable by default, with real depth underneath.

What the Wallet Does

Send to anyone. Scan a QR code or paste an address. The wallet detects the network — Lightning, Liquid, or on-chain — and routes the payment automatically. You do not need to know which network you are using. The wallet handles it.

Receive from anywhere. Every user gets a reusable Lightning address (BOLT12), and can generate one-time Lightning invoices (BOLT11), Liquid addresses, and on-chain addresses. Whether someone sends you sats from a Lightning wallet, a Liquid wallet, or an on-chain transaction — it all arrives in the same balance.

One balance. There is no Lightning balance and on-chain balance. There is one balance. View it in sats, GBP, USD, EUR, or JPY.

Self-custody from day one. Keys are generated on your device during setup. They never leave your device. They are never transmitted to our servers. You control your sats. If you lose your device without backing up your seed phrase, nobody — including us — can recover your funds. That is what self-custody means.

The Technology: Breez SDK

The wallet is powered by Breez Technology's Nodeless SDK (Liquid implementation) — an open-source, self-custodial Lightning integration built in Rust. The same SDK powers Misty Breez and is used by a growing number of Lightning-enabled applications across the Bitcoin ecosystem.

How It Works Under the Hood

Traditional Lightning wallets require each user to run a Lightning node with open payment channels. That means managing inbound liquidity, dealing with channel closures, handling routing failures, and paying setup fees — real engineering problems that take years to solve well and create friction for end users.

Breez SDK's Nodeless implementation takes a fundamentally different approach. Instead of payment channels, it uses the Liquid Network as a settlement layer and performs atomic submarine swaps to bridge between Lightning and Liquid.

When you send a Lightning payment: The SDK performs a submarine swap — converting L-BTC from your Liquid wallet into sats on the Lightning Network, then forwarding them to the recipient. From the user's perspective, you scan a QR code and the payment arrives.

When you receive a Lightning payment: The SDK performs a reverse submarine swap — the sender pays a swap invoice, the swap provider (Boltz) locks L-BTC to a Liquid address, and the SDK claims those funds into your wallet. Two Liquid on-chain transactions, fully automated.

When two Breez SDK wallets transact with each other: The SDK uses Magic Routing Hints — an optimisation built on the Boltz swap protocol. Instead of performing a full Lightning-to-Liquid-to-Lightning round trip, the SDK detects that both parties are on Liquid and routes the payment as a direct Liquid transaction. One on-chain transaction instead of two swaps. Lower fees, faster settlement.

When you send or receive on-chain Bitcoin: The SDK performs a swap between Liquid and the Bitcoin main chain automatically. The user does not need to manage or even understand this process.

No Channels, No Nodes, No LSPs

Because the Nodeless implementation does not use payment channels, there are no setup fees, no Lightning Service Provider (LSP) dependencies, and no channel management overhead. Users see a single balance and can send and receive immediately. There are no channel closures to wait for, no force-close scenarios, and no liquidity constraints that prevent receiving payments.

This is what makes the wallet work for families. A child opening their first Bitcoin wallet should not encounter a "waiting for channel" message or an "insufficient inbound liquidity" error. They should see a balance and be able to use it.

Payment Protocol Support

The SDK handles virtually every Bitcoin payment protocol in use today: BOLT11 invoices, BOLT12 offers, BIP353 (DNS-based payment instructions), LNURL-Pay, LNURL-Withdraw, Lightning addresses, and on-chain BTC addresses. This means our wallet can interact with nearly any Bitcoin wallet or service in the ecosystem — from a merchant running BTCPay Server to a friend using Phoenix or Wallet of Satoshi.

The SDK also supports receiving payments while the app is in the background or closed, using webhook-based notifications that wake the app to process incoming transactions. On mobile, this works through push notifications — the swap provider calls a Notification Delivery Service via webhook, which triggers the app's background process to claim the incoming funds.

Fee Structure

Breez SDK fees are low and transparent. Receiving a Lightning payment costs a swap service fee of 0.25% plus two small Liquid transaction fees (roughly 47 sats combined for the lockup and claim). Sending to a Bitcoin address costs a swap service fee of 0.1% plus Liquid and Bitcoin transaction fees based on current mempool conditions. Direct Liquid-to-Liquid payments between SDK wallets (via Magic Routing Hints) cost approximately 26 sats — with zero fees for the receiver.

For the small amounts typical in a family education app — lesson rewards, chore earnings, sats-back — these fees are negligible.

Why We Chose Breez SDK

We evaluated several approaches to building the wallet. Building Lightning infrastructure from scratch was not realistic for a small team — the engineering complexity of channel management, liquidity, and routing is substantial. Breez SDK gave us a production-ready, self-custodial Lightning integration that let us focus our engineering effort on the education and family features that differentiate BTCBitByBit.

The SDK is written in Rust (83.7% of the codebase) with bindings for Swift, Kotlin, React Native, Flutter, and Python. It is actively maintained, well-documented, and free for developers to use. The ecosystem around it is growing quickly — in Q4 2025 alone, twelve new partners shipped integrations spanning wallets, trading platforms, healthcare finance, and enterprise payroll. In January 2026, European neobank Deblock went live with the SDK, bringing self-custodial Bitcoin to over 300,000 users across Europe. Breez also offers a second nodeless implementation built on Spark's statechain-based Layer 2, giving developers an additional option alongside Liquid. The older Greenlight (native) implementation, which used Blockstream's cloud-hosted nodes, has been deprecated in favour of the Nodeless implementations.

Why Liquid

The Nodeless SDK uses the Liquid Network — a Bitcoin sidechain developed by Blockstream and operated by a federation of 81 member organisations, including exchanges, trading desks, and Bitcoin-focused companies. Fifteen of those members run the hardware that secures the network, signing blocks in a round-robin process that requires at least 11 of 15 to agree on every block. Blocks settle every minute with low fees.

This is a different security model to Bitcoin's main chain, which is secured by proof-of-work. Liquid is secured by a known federation under a multisig arrangement. We want to be transparent about that distinction — it matters, and Bitcoiners should understand it.

That said, Liquid gives us exactly what we need: fast, low-cost transactions with self-custody. Lightning payments route seamlessly through submarine swaps. On-chain withdrawals are available at any time — the SDK handles the swap automatically. And users always hold their own keys, whether their balance is 500 sats or 5 million.

The Wallet in Practice

For Individual Users

Download the app. Subscribe. Your wallet is ready in seconds. Start a Learn & Earn course, pass the quiz, and earned sats arrive in your Redeem tab. Withdraw to your wallet whenever you want. Your sats-back rewards accumulate there too. Everything flows to the same self-custody wallet.

For Families

Every family member — parents and children — gets their own wallet. Parents configure each child's wallet mode:

Earn-only mode. The child can receive sats from the parent and send them back. No external transactions. No outgoing payments to unknown addresses. The parent controls the flow. This is designed for younger children or anyone just starting with Bitcoin.

Full self-custody mode. The child gets their own keys on their own device. They can send to any Lightning, Liquid, or on-chain address. They manage their own seed phrase. Full ownership, full responsibility.

The transition from earn-only to full self-custody is itself part of the education. Explaining what keys are. What a seed phrase means. Why nobody can recover it for them. That conversation — guided by a parent, prompted by a real wallet with real sats — is more valuable than any textbook chapter on cryptography.

Why Self-Custody Matters for Education

We could have built a custodial wallet. It would have been simpler. No seed phrases to manage. No risk of lost keys. Easier onboarding.

But custodial wallets teach the wrong lesson. They teach that someone else holds your money and you trust them to give it back. That is how traditional banking works. It is the opposite of what Bitcoin was designed to do.

Self-custody teaches ownership. It teaches that your keys are your responsibility. That backing up a seed phrase matters. That nobody can freeze your funds or deny you access. These are not abstract concepts when you are holding sats you earned from a quiz or a chore. They are practical realities.

98.6% of people with high Bitcoin knowledge own Bitcoin — knowledge drives action. By giving users a self-custody wallet from day one, we are not just teaching about Bitcoin. We are putting Bitcoin in their hands and letting the wallet itself be the teacher.

What We Are Building Next

The wallet is live and functional. But we are continuing to build on top of it:

• Spending limits per child — parents set maximum send amounts
• Transaction notifications — alerts when sats move in or out of a child's wallet
• Feature toggles — enable or disable specific wallet functions per child
• Granular parental controls — restrict access to specific actions based on the child's readiness

The goal is to give parents complete control over how much responsibility they hand over, and when.

Try It

BTCBitByBit is in beta on iOS (TestFlight) and Android (Play Store). Your self-custody wallet is ready the moment you open the app.

Subscribers get sats-back every month. During beta, use code BETA2026B when you subscribe to get 100% sats-back — making the subscription effectively free. Any sats you earn from lessons or chores are yours to keep and withdraw whenever you want.

btcbitbybit.com | Code: BETA2026B

BTCBitByBit is a product of KayGee Tech Ltd. We do not provide financial advice. Bitcoin is volatile and you should do your own research before buying or holding any amount. Self-custody means you are responsible for your own keys — if you lose your seed phrase, your funds cannot be recovered by anyone.