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

# Introduction

> cubic is the top-ranked AI code reviewer on Code Review Bench for complex codebases on GitHub.

<CardGroup cols={2}>
  <Card title="Install the AI code reviewer" icon="rocket" href="https://cubic.dev/sign-up">
    7 days free, no credit card required.
  </Card>

  <Card title="Talk to an engineer" icon="calendar" href="https://cubic.dev/paul">
    Learn more about cubic and how it works.
  </Card>
</CardGroup>

<Note>
  **Independent benchmark**: cubic is the
  [top-ranked AI code reviewer](https://www.cubic.dev/blog/cubic-is-the-best-ai-code-reviewer-on-martian-s-benchmark)
  on [Code Review Bench](https://codereview.withmartian.com/?mode=offline).
</Note>

## Key features

* **Spots bugs and improvements**: Comments on bugs and improvements in pull requests
* *Stays out of your way*: Only surfaces issues worth your attention, with minimal verbosity, and auto-resolves addressed issues. No poems or pointless noise.
* **Learns from you**: Improves over time by learning from your feedback
* **PR summaries**: Generates PR descriptions based on code changes
* **Custom agents**: Enforce your team's coding standards
* **Background agents**: Automatically fix issues in the background using Claude Code in a Sandboxed environment.

<img src="https://mintcdn.com/cubic-2/ShUaZcDyEhB-G1ZC/ai-review/images/example-review.png?fit=max&auto=format&n=ShUaZcDyEhB-G1ZC&q=85&s=a866cf95962b8d4892ce1c619fbdc8b5" alt="Example review" className="border border-zinc-800 rounded-lg" width="1948" height="1538" data-path="ai-review/images/example-review.png" />

## Getting started

<Steps>
  <Step title="Install cubic and start your free trial">
    Sign up at [cubic.dev/sign-up](https://cubic.dev/sign-up). This will guide you through
    installing the cubic GitHub App on the repositories you want to analyze.
  </Step>

  <Step title="Open a new pull request">
    Once installed, cubic will automatically review new new pull requests. See an [example reviews
    for Posthog, n8n and more](https://cubic.dev/examples).
  </Step>

  <Step title="Learn the workflow">
    Follow the [Developer Quickstart](/ai-review/quickstart) for a hands-on tutorial on interacting
    with AI reviews, setting up custom agents, and using background agents.
  </Step>
</Steps>

<Tip>
  Want cubic inside Cursor, Claude Code, Codex, or another coding agent? Start with
  [Connect cubic to your IDE](/ide/agent-setup) and [Local CLI review](/ide/cli-review).
</Tip>

<Note>
  **Existing pull requests**: Reviews for new PRs start automatically. To review a PR that was
  opened *before* you installed the app, comment: `@cubic-dev-ai review this PR`.
</Note>

## Security and privacy

We take the security of your code seriously. Our systems are built with the following principles in mind:

* **No code stored:** We never permanently store your source code. It's processed in a short-lived, isolated sandbox and is irreversibly deleted as soon as the review completes.
* **No AI model training:** Our AI providers are contractually prevented from using your code to train their models.
* **SOC 2 compliant:** We are SOC 2 Type I compliant.

For more details, see our full [Privacy & Security documentation](/account/privacy-security).

## Frequently asked questions

<AccordionGroup>
  <Accordion title="Do you support Gitlab or Bitbucket?">
    Not yet. We currently only support **GitHub**.
  </Accordion>

  <Accordion title="What languages do you support?">
    cubic is language-agnostic and supports all popular programming languages, including JavaScript,
    TypeScript, Python, Go, Ruby, PHP, Java, C#, C/C++, Rust, Kotlin, and Swift.
  </Accordion>

  <Accordion title="What AI models do you use?">
    We use a mix of leading model providers. Our system is designed to select the best model for a
    given task, and we continuously upgrade our models to ensure the highest quality suggestions.
  </Accordion>

  <Accordion title="Will cubic also check large PRs?">
    If a pull request contains more than 100 files (excluding binary files and those matching ignore
    patterns), cubic will review the highest-priority 100 eligible files. Ultrareview increases this
    limit to 200 eligible files.
  </Accordion>

  <Accordion title="Does cubic have up-to-date knowledge of libraries?">
    Yes. cubic has access to current documentation for the libraries and frameworks in your stack,
    so suggestions account for the latest APIs, deprecations, and best practices—not outdated
    patterns from stale training data.
  </Accordion>
</AccordionGroup>

## Next steps

* [**Developer Quickstart**](/ai-review/quickstart): Hands-on tutorial for interacting with AI reviews.
* [**Connect cubic to your IDE**](/ide/agent-setup): Install cubic in Cursor, Claude Code, VS Code, Codex, Gemini CLI, or another coding tool.
* [**Local CLI review**](/ide/cli-review): Add the advanced local-review loop before you push.
* [**Key features**](/ai-review/key-features): Discover what the AI reviewer can do.
* [**Custom review rules**](/ai-review/custom-agents): Tailor the AI to your team's coding standards.