Lightning payments that just work
Spark is the wallet you'll use every day. Instant Lightning payments, a Lightning Address that receives even while you're offline, and a Stable Balance switch that holds your balance's dollar value. All self-custodial, all from the same seed as the rest of Tenshu.
Your everyday Bitcoin wallet
Instant Lightning
Pay any BOLT11 invoice, LNURL, or Lightning Address. Sub-second settlement, fees measured in sats.
Your own Lightning Address
Get paid at [email protected]. Invoices are minted for you even when your device is offline. The sats are waiting when you come back.
Stable Balance
One switch pegs your spending balance to the dollar. No stablecoin juggling, no extra accounts. Flip it off to return to pure BTC.
One seed, self-custody
Spark shares one seed and PIN with the rest of Tenshu. Your keys never leave your device.
Stable Balance: spend like cash, live on Bitcoin
Bitcoin's price moves. Your rent doesn't. Stable Balance is a single toggle in your Spark settings: turn it on and your balance holds its dollar value instead of floating with the Bitcoin price. Under the hood the wallet automatically converts your sats into a dollar-pegged token, but you never manage a second asset or a second account. You see one balance, marked Stable, and it stays put.
Change your mind? Flip the toggle off and you're back to a pure Bitcoin balance. No exchange, no withdrawal, no counterparty holding your funds. It's still your wallet and your keys the entire time.
Stablecoins, without holding stablecoins
Pay and get paid in USDT and USDC while your balance stays in Bitcoin.
Send USDT and USDC
Pay any USDT or USDC recipient straight from your Bitcoin balance, across 30+ networks: EVM chains, Solana, Tron, and more. The conversion happens at payment time, so you hold Bitcoin (or your Stable Balance) the whole time and never a stablecoin.
Get paid in USDT, USDC, and 100+ assets
Accept payment in USDT, USDC, or 100+ other assets and it arrives as Bitcoin in your Spark wallet. The conversion is handled by SideShift, a third-party service, and availability varies by jurisdiction.
Prefer dollars? Keep your balance in Stable Balance and incoming payments hold their dollar value automatically, with no stablecoin to manage.
How Spark works
Spark is COINCUBE's default Lightning wallet, built on the Spark protocol, a statechain-based Bitcoin Layer 2 that transfers real Bitcoin instantly by rotating keys instead of moving coins on-chain. It stays self-custodial: you hold one of the two signing keys, and you can always exit back to the Bitcoin main chain unilaterally. There are no channels to open and no liquidity to manage. Scan an invoice or type a Lightning Address, and the payment settles in under a second. COINCUBE integrates it through the Breez Spark SDK on Bitcoin mainnet.
Receiving is just as simple. Your @coincube.io Lightning Address is served by hosted infrastructure that mints invoices on your behalf, so payments arrive even when the app is closed. Moving on-chain Bitcoin in? Send it to your static deposit address and claim it into Spark once it confirms.
Spark lives alongside your other Tenshu wallets and derives from the same seed. Cold storage stays in the Vault; Spark is the balance you spend from day to day.
Bitcoin you can actually spend
Open source. Free forever.