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README.md

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-Cross-chain Bitcoin transaction verification and other Bitcoin things for Stacks smart contracts.
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+`bitcoin.clar` is a Clarity library that you can use in your smart contracts to do various operations that involve Bitcoin. 
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+`bitcoin.clar`'s primary feature currently is cross-chain transaction verification. This means you can verify that Bitcoin transactions happened in a trustless smart contract on the [Stacks blockchain](https://stacks.co).
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+It currently powers [Catamaran swaps](https://www.catamaranswaps.org) & [Sypool](https://sypool.co)'s transaction verification. We built `bitcoin.clar` specifically for Sypool, but the applications of verifying Bitcoin transactions through smart contracts are far more than that. We're trying to build docs and make this a library that other developers in the ecosystem can use too!
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