Find bugs with ultrareview
Run a deep, multi-agent code review in the cloud with /code-review ultra to find and verify bugs before you merge.
Ultrareview is a deep code review that runs on Claude Code on the web infrastructure. When you run /code-review ultra, Claude Code launches a fleet of reviewer agents in a remote sandbox to find bugs in your branch or pull request.
Compared to a local /code-review or /review, ultrareview offers:
- Higher signal: every reported finding is independently reproduced and verified, so the results focus on real bugs rather than style suggestions
- Broader coverage: a larger fleet of reviewer agents explores the change in parallel, which surfaces issues that a local review can miss
- No local resource use: the review runs entirely in a remote sandbox, so your terminal stays free for other work while it runs
Ultrareview requires authentication with a claude.ai account because it runs on Claude Code on the web infrastructure. If you are signed in with an API key only, run /login and authenticate with claude.ai first. Ultrareview is not available when using Claude Code with Amazon Bedrock, Google Cloud's Agent Platform, or Microsoft Foundry, and it is not available to organizations that have enabled Zero Data Retention. When ultrareview is not available, /code-review ultra runs a local review in your session instead.
Run ultrareview from the CLI
Start a review from any git repository in the Claude Code CLI.
/code-review ultra
Without arguments, ultrareview reviews the diff between your current branch and the default branch, including any uncommitted and staged changes in your working tree. Claude Code bundles the repository state and uploads it to a remote sandbox for the review. To compare against a different base, such as on a repository whose integration branch is develop or trunk, pass the branch name instead: /code-review ultra develop. {/* min-version: 2.1.212 */}A base branch that exists only on origin is fetched, and a name with a typo gets a closest-branch suggestion. Both behaviors require Claude Code v2.1.212 or later.
If your branch shares no merge base with the base branch, for example when the two histories are unrelated, Claude Code offers to review every tracked file in the repository instead. The whole-repository fallback requires a full clone and applies the same size limits as a branch review. Before v2.1.214, /code-review ultra refused to run without a merge base.
To review a GitHub pull request instead, pass the PR number.
/code-review ultra 1234
The command also accepts #1234, PR 1234, and pasted PR URLs. A pasted URL must point to the repository in your current directory. Before v2.1.212, the command accepted only the bare number and rejected other forms with a not-a-branch error.
In PR mode, the remote sandbox clones the pull request directly from the host rather than bundling your local working tree. PR mode works with repositories on github.com and on GitHub Enterprise Server instances that an Owner has connected to Claude Code.
Before launching, Claude Code shows a confirmation dialog with the review scope (including the file and line count when reviewing a branch), your remaining free runs, and the estimated cost. After you confirm, the review continues in the background and you can keep using your session. The command runs only when you invoke it with /code-review ultra; Claude does not start an ultrareview on its own.
Pricing and free runs
Ultrareview is a premium feature that bills against usage credits rather than your plan's included usage.
| Plan | Included free runs | After free runs |
|---|---|---|
| Pro | 3 free runs | billed as usage credits |
| Max | 3 free runs | billed as usage credits |
| Team and Enterprise | none | billed as usage credits |
- Free runs: the three Pro and Max runs are a one-time allotment per account and don't refresh.
- Cost per review: after you use the free runs, or after the free-run period ends, typically $5 to $25 in usage credits depending on the size of the change, matching the estimate the launch dialog shows before each run.
- When a run counts: once the cloud session starts. A review you stop early or that fails to complete still uses a free run; a paid review bills only for the portion that ran.
Because ultrareview always bills as usage credits outside the free runs, your account or organization must have usage credits turned on before you can launch a paid review. If usage credits aren't turned on, Claude Code blocks the launch, and how you turn them on depends on your billing access:
- If you can manage billing for your account, Claude Code links you to the billing settings where you can turn on usage credits.
- On Team and Enterprise plans, members without billing access send a request from the CLI asking their admin to turn on usage credits.
You can also run /usage-credits to check or change your usage-credits setting.
Claude Code asks you to confirm usage-credits billing once per conversation. When you start a new conversation, for example with /clear, Claude Code shows the billing confirmation again for the next paid review. Before v2.1.212, a confirmation from an earlier conversation carried over, so a paid review after /clear launched without showing the billing confirmation.
Track a running review
A review typically takes 5 to 10 minutes. The review runs as a background task, so you can keep working in your session, start other commands, or close the terminal entirely.
Use /tasks to see running and completed reviews, open the detail view for a review, or stop a review that is in progress. Stopping a review archives the cloud session, and partial findings are not returned. When the review finishes, the verified findings appear as a notification in your session. Each finding includes the file location and an explanation of the issue so you can ask Claude to fix it directly.
Run ultrareview non-interactively
Use the claude ultrareview subcommand to start an ultrareview from CI or a script without an interactive session. The subcommand launches the same review as /code-review ultra, blocks until the remote review finishes, prints the findings to stdout, and exits with code 0 on success or 1 on failure.
claude ultrareview
claude ultrareview 1234
claude ultrareview origin/main
Without arguments, the subcommand reviews the diff between your current branch and the default branch, with the same whole-repository fallback as /code-review ultra when no merge base exists. Pass a PR number to review a pull request, or pass a base branch to review the diff against that branch instead. Invoking the subcommand counts as consent for the whole-repository fallback and for the billing and terms prompt that the interactive command shows, so the run starts without waiting for input.
If the base branch you pass exists on origin but not in your local clone, Claude Code fetches it and continues. If the name matches no branch, the error message suggests the closest branch name. Before v2.1.212, both cases failed with a not-a-branch error.
Progress messages and the live session URL go to stderr so stdout stays parseable. Use these flags to control the output and timeout:
| Flag | Description |
|---|---|
--json |
Print the raw bugs.json payload instead of the formatted findings |
--timeout <minutes> |
Maximum minutes to wait for the review to finish. Defaults to 30 |
Running claude ultrareview requires the same authentication and usage credit configuration as /code-review ultra. The subcommand exits with code 0 when the review completes with or without findings, code 1 when the review fails to launch, the cloud session errors, or the timeout elapses, and code 130 when interrupted with Ctrl-C. The remote review keeps running if you interrupt the subcommand; follow the session URL printed to stderr to watch it in the browser.
For automatic reviews on GitHub pull requests, Code Review integrates with your repository directly and posts findings as inline PR comments without a CLI step.
How ultrareview compares to /code-review and /review
All three commands review code, but they target different stages of your workflow.
/code-review |
/review <pr> |
/code-review ultra |
|
|---|---|---|---|
| Target | your working diff | a GitHub pull request | your working diff or a pull request |
| Runs | locally in your session | locally in your session | remotely in a cloud sandbox |
| Depth | scales with the effort argument | a single-pass review at the session's effort | multi-agent fleet with independent verification |
| Duration | seconds to a few minutes | seconds to a few minutes | roughly 5 to 10 minutes |
| Cost | counts toward normal usage | counts toward normal usage | free runs, then roughly $5 to $25 per review as usage credits |
| Best for | quick feedback while iterating | reviewing a teammate's PR before approving | pre-merge confidence on substantial changes |
Use /code-review for fast feedback as you work. Use /review <pr> to look over a pull request the same way you would before approving it. Use /code-review ultra before merging a substantial change when you want a deeper pass that catches issues a local review might miss.
Related resources
- Claude Code on the web: learn how cloud sessions and cloud sandboxes work
- Plan complex changes with ultraplan: the planning counterpart to ultrareview for upfront design work
- Manage costs effectively: track usage and set spending limits