CKB is a UTXO-based blockchain that natively supports Bitcoin and EVM wallets — making it uniquely suited for cross-chain applications.

CCC is the TypeScript SDK that makes building on CKB approachable: it handles wallet connections, transaction composition, and cross-chain signing, so you can focus on your product instead of the plumbing.

## What you can do with CCC [#what-you-can-do-with-ccc]

* **Explore CKB hands-on**: Run live code examples in the browser — no setup needed.
* **Query the chain**: Fetch cells, track assets, and process blockchain data with a typed API.
* **Compose transactions**: Build transactions with an intuitive API — CCC handles input selection and fee calculation for you.
* **Sign messages**: Use a single `Signer` interface that works across EVM, Bitcoin, Nostr, and more — regardless of wallet type or chain.
* **Connect wallets**: Drop in the connector component and go, or build a fully custom wallet UI for React or any framework.

## Who uses CCC [#who-uses-ccc]

CCC powers production applications across the CKB ecosystem — including
[NervDAO](https://nervdao.com/), [UTXO Global](https://utxo.global/),
[Mobit](https://mobit.app/), [Omiga](https://omiga.io/),
[Nervape](https://www.nervape.com/), [UTXOSwap](https://utxoswap.xyz/),
[D.ID](https://d.id/), [Bool Network](https://bool.network/),
[World3](https://world3.ai/), and more. If you're building something new on CKB, you're in good company.

## Ecosystem links [#ecosystem-links]

* [CCC Playground](https://live.ckbccc.com/) — Run CCC code instantly in your browser, with live data and shareable snippets.
* [CCC App](https://app.ckbccc.com/) — A mini-toolset showcasing common CKB scenarios.
* [API Reference](https://api.ckbccc.com) — Full TypeScript API documentation.
* [Nervos CKB Docs](https://docs.nervos.org/) — Background knowledge on the CKB blockchain.
* [RGB++ SDK](https://github.com/rgbplusplus/rgbpp-sdk) — Issue assets on BTC L1 backed by CKB's VM.
* [Spore SDK](https://github.com/sporeprotocol/spore-sdk) — On-chain digital objects (DOBs) protocol.

<Callout type="warning">
  [Lumos](https://github.com/ckb-js/lumos) is no longer actively maintained. We recommend CCC for all new projects.
</Callout>

## Next steps [#next-steps]

<Cards cols="2">
  <Card title="Quick start" icon="<Rocket />" href="./quick-start">
    Send your first CKB transaction on-chain with CCC — in under 5 minutes.
  </Card>

  <Card title="Installation" icon="<Package />" href="./installation">
    Install CCC for React, Node.js, Web Component, or custom UI.
  </Card>

  <Card title="Core concepts" icon="<BookOpen />" href="../concepts/cell-model">
    Understand the building blocks behind every CKB app — and how they fit together.
  </Card>

  <Card title="Guides" icon="<Map />" href="../guides/connect-wallets">
    Find the recipe for what you're trying to build — step-by-step.
  </Card>
</Cards>


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> ## Documentation Index
> Fetch the complete documentation index at: https://docs.ckbccc.com/llms.txt
> Use this file to discover all available pages before exploring further.