> For the complete documentation index, see [llms.txt](https://scroll-zkp.gitbook.io/scroll-guide/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://scroll-zkp.gitbook.io/scroll-guide/contribute-to-scroll/repositories.md).

# Repositories

{% hint style="danger" %}
**Scroll Alpha Testnet is now deprecated.**

Please visit our new documentation for the Scroll Sepolia Testnet at <https://docs.scroll.io/>
{% endhint %}

Scroll’s Github mainly consists of a few major public repositories open for contributions:

### [scroll-tech/zkevm-circuits](https://github.com/scroll-tech/zkevm-circuits)

This is the main repo for implementing the zkEVM.

See this [introduction](https://github.com/privacy-scaling-explorations/zkevm-specs/blob/master/specs/introduction.md) or the [zkEVM docs](https://privacy-scaling-explorations.github.io/zkevm-docs/) for more details.

### [scroll-tech/zkevm-specs](https://github.com/scroll-tech/zkevm-specs)

Defines specifications of circuits in the zkEVM. This writeup clearly defines what will be implemented, and it also provides a python-equivalent implementation for debugging and testing before actual implementation.

### [scroll-tech/go-ethereum](https://github.com/scroll-tech/go-ethereum)

This is a fork of Ethereum's client to run as a Layer 2 sequencer.&#x20;

### [scroll-tech/frontends](https://github.com/scroll-tech/frontends)

A single React app written in TypeScript to accommodate for all official Scroll frontend functionality. This includes the homepage, dev portal, bridge frontend and rollup explorer frontend.

## Which repo to Contribute to?

Checkout each repo's `CONTRIBUTING.md` file to learn more about making contributions.&#x20;

For zkEVM circuits, contributions are mostly sent to the PSE `zkevm-circuits` repo first, as Scroll inherits all commits into its fork. All updates to `scroll-tech/zkevm-circuits` should be upstreamed to PSE’s `zkevm-circuits`. If you have a feature that is Scroll-specific, please contact a maintainer in our [discord](https://discord.com/invite/scroll).


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