Lightspark introduces a layer 2 for instant payments, stablecoins and interoperability with Lightning.
Spark is an open-source layer 2 protocol developed by Lightspark, designed to offer instant low-cost payments without the need for intermediaries. It allows the creation of wallets and applications that interact directly with the Bitcoin and Lightning networks. The company’s stated goal is to transform Bitcoin into a true global digital currency, solving the scalability limitations of the base layer.
Lightspark, a company led by David Marcus (former PayPal and former Facebook), officially launched Spark in beta version on April 29, 2025. Developers can already use Spark’s SDKs (Wallet and Issuer) to build self-custodial wallets compatible with Lightning and tokens (such as stablecoins) native to the Bitcoin network.
How it works
Spark adopts a statechain-based approach, allowing the transfer of ownership of a UTXO off-chain between different users without using the main blockchain, thus reducing costs and transaction times. Instead of executing an on-chain transaction that physically moves the asset, users acquire signing rights or control over a key that represents a bitcoin UTXO. Transfers occur through a chain of signatures and a mechanism that allows subsequent transactions to overwrite previous ones, ensuring that neither the user nor the service provider (Spark Service Provider, SSP) can lose funds during the operation.
Spark is designed to be fully interoperable with LN, supporting not only bitcoin transactions, but also stablecoins and other tokenized assets. SSPs facilitate Lightning payments by accepting funds on Spark and converting them into Lightning transactions or vice versa, eliminating the need for users to manage nodes or worry about channel liquidity. For example, a user can pay an LN invoice with a stablecoin on Spark, with the SSP converting the stablecoin to BTC in the background and sending the funds to the recipient.
Shared signature model (multisig 2-of-2)
Unlike the LN trust model, which is based on peer-to-peer bidirectional channels with smart contract logic, Spark involves a coordinating entity, the “Spark Service Provider” (SSP). This shifts part of the risk from channel liquidity management to trust in operators who sign off-chain transactions. The SSP’s task is to sign “blindly” (blindly) on behalf of the user, which means the SSP does not see the content of the signature and does not even know if it is signing a Bitcoin transaction or something else.
Bitcoin deposited on Spark always remains under the user’s control. When a user sends funds to Spark, they are initially transferred to a statechain. Once funds are on the statechain, payments on the Spark network occur instantly and at near-zero costs.
At the heart of Spark’s security is the use of a shared signature scheme, specifically a multisig 2-of-2 model. This means that two keys are required to authorize a transaction, and the user always holds one. When users deposit funds on Spark, they send them to a multisig address. Here, they maintain control of their funds and can perform a unilateral exit without the need to interact with other parties.
Each payment is enabled by a Spark Service Provider (SSP), which must co-authorize the transaction together with the user for it to be valid and successful.
Although the network is currently managed only by Lightspark and another operator (Flashnet), users do not risk losing funds even if these operators stopped cooperating. In fact, Spark offers the possibility to unilaterally force the return of bitcoin to the mainnet at any time. Users can exit Spark in two ways: through a cooperative exit (cheaper and faster) or a unilateral exit (slower, but possible in case of malfunction or loss of trust). Lightspark has declared its intention to add more operators in the future to increase decentralization.
Fee structure
Regarding fees, transactions within the Spark network are zero fee. The only fees users will have to bear are Bitcoin’s on-chain fees for depositing or withdrawing funds from Spark. Additionally, transferring bitcoin from Spark to LN involves a 0.25% fee plus routing fees. Conversely, a transaction from LN to Spark costs 0.15%.
The native LRC20 token protocol
Introduced in the summer of 2024, LRC20 is a token issuance protocol designed to be compatible with both Bitcoin’s mainnet and LN. Anyone can issue an LRC20 token. The protocol also supports freeze and burn operations, giving the original issuing wallet the power to freeze tokens at any address, preventing transactions until unlocked. LRC20 is primarily designed for issuing stablecoins and regulated assets.
After thoroughly testing it, the Lightspark team decided to run the LRC20 protocol natively on Spark, to enable token issuance on the network.
Ecosystem and partnerships
The birth of Spark has immediately attracted the interest of other Bitcoin projects. Among the various partnerships established, the multisig wallet Theya has integrated Spark to offer its users simpler and faster bitcoin and stablecoin payments.
Last May, Breez announced a new implementation of the Breez SDK based on Spark, which allows developers to integrate Lightning payments directly into their apps through Spark. As part of this collaboration, Breez will also act as a Spark Service Provider, helping to expand the ecosystem. According to the two companies, this partnership will provide developers with new Bitcoin-native tools for use cases such as streaming payments, international remittances and micro-payments for AI.
