# Spark

> Bitcoin's payment layer for stablecoins and instant BTC transfers.

Spark is a Bitcoin Layer 2 protocol enabling instant, self-custodial Bitcoin transfers without broadcasting on-chain transactions. Built on statechains with FROST threshold signatures. Supports native token issuance (BTKN standard), Lightning Network interoperability, and stablecoins like USDB.

- Founded by Lightspark
- Open source: [github.com/buildonspark/spark](https://github.com/buildonspark/spark)
- 20+ live integrations including Wallet of Satoshi, Breez, Xverse, Privy, Tether WDK, and Flashnet

## Core Technology

Spark uses a two-of-two multisig model where one key belongs to the user and operators collectively hold the other via FROST threshold signing. Transfers change key ownership off-chain: the on-chain UTXO never moves. The protocol provides 1-of-n security (one honest operator keeps funds safe), perfect forward security (past transfers are safe even if operators are later compromised), and unilateral exit to Bitcoin L1 at any time.

## Documentation

- [Spark Docs](https://docs.spark.money): Complete API reference, SDK guides, and integration tutorials
- [Bitcoin Wallet SDK](https://www.spark.money/solutions/bitcoin-wallet-sdk): Add Bitcoin, Lightning, and stablecoins to any app

## Research

- [What is Spark? Bitcoin Layer 2 Built on Statechains](https://www.spark.money/research/what-is-spark-bitcoin-layer-2): Technical deep dive on statechains, FROST signatures, and leaf architecture
- [Zero-Conf Bitcoin Explained](https://www.spark.money/research/zero-conf-bitcoin-explained): How instant Bitcoin deposits work without confirmation delays
- [Lightning Network Liquidity Explained](https://www.spark.money/research/lightning-network-liquidity-explained): How liquidity management works in Lightning
- [Bitcoin Multisig Wallets Explained](https://www.spark.money/research/bitcoin-multisig-wallets-explained): Comprehensive guide to multi-signature security
- [Taproot and Schnorr Signatures Explained](https://www.spark.money/research/taproot-schnorr-signatures-explained): Privacy and efficiency improvements in modern Bitcoin
- [UTXO Model vs Account Model](https://www.spark.money/research/utxo-model-vs-account-model): Understanding Bitcoin's transaction model
- [USDB: Stablecoin That Pays Bitcoin Yield](https://www.spark.money/research/usdb-stablecoin-pays-bitcoin): How Bitcoin-native stablecoins work with yield generation

## Glossary

- [Full Glossary](https://www.spark.money/glossary): 40+ terms covering Lightning Network, Bitcoin protocol, and stablecoin concepts (HTLCs, PTLCs, onion routing, channel management, and more)

## Tools

- [Bitcoin Tools](https://www.spark.money/tools): 70+ free calculators, converters, and comparisons (sats converter, DCA calculator, fee estimator, Lightning vs Visa, stablecoin comparison, and more)
- [Bitcoin Address Privacy Audit](https://www.spark.money/address): Check any Bitcoin address for privacy exposure, entity labels, and transaction history

## FAQ

- [Frequently Asked Questions](https://www.spark.money/faq): Common questions about Spark, Lightning, stablecoins, and SDKs

## Optional

- [News and Announcements](https://www.spark.money/news): Latest partnerships and product updates
- [Ecosystem](https://www.spark.money/ecosystem): Live integrations and partners
- [Brand Assets](https://www.spark.money/brand): Logos, colors, and brand guidelines