# What are Bitcoin appchains?

Bitcoin appchains (or Bitcoin L3s) are designed for application-specific blockchains.

They are ZK rollups. But instead of rolling up to Bitcoin directly, they roll up to a Bitcoin L2.

It is more cost-effective for smaller teams and indie developers to have their own blockchain and focus on a single application.

<figure><img src="/files/V2uNqKATXJvNMdm7dUWV" alt=""><figcaption></figcaption></figure>


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