Source: https://codereviewguide.fyi/coderabbit-vs-what-the-diff/ [AI code review head-to-head library](https://codereviewguide.fyi/tool-comparisons/) # CodeRabbit vs What The Diff What The Diff focuses on PR descriptions, diff review and inline refactoring through Git integrations. CodeRabbit also documents local CLI review. The decision is whether the immediate job is communicating a PR or inspecting a repair before it is pushed. Code Review Guide · Reviewed October 14, 2026 · Published by Perch / Verglas LLC ## CodeRabbit and What The Diff at a glance Documented review inputs, requirements and licensing | Decision | CodeRabbit | What The Diff | | --- | --- | --- | | Review scope | Pull requests, local changes, and agent-loop review. | PR descriptions, diff review and inline refactoring. | | Local review input | CLI and IDE review committed and uncommitted changes. | GitHub and GitLab integrations; dedicated CLI review was not documented. | | Custom requirements | Guideline files and natural-language pre-merge checks; custom-check allowances depend on plan. | Token limits and excluded file patterns; semantic rule format not documented. | | License and service | Commercial review service. | Commercial service; qualifying OSS sponsorship. | | Official references | [CodeRabbit sources](https://codereviewguide.fyi/coderabbit-vs-what-the-diff/#sources-coderabbit) | [What The Diff sources](https://codereviewguide.fyi/coderabbit-vs-what-the-diff/#sources-what-the-diff) | ## Compare PR explanation with verification before a commit Evaluate the usefulness of the PR description separately from defect findings. Record token allowance consumption and whether the workflow can inspect the uncommitted repair. ### CodeRabbit billing Essentials: $24/user/month billed annually, or $30 monthly. Public-repository reviews are free. Essentials annual subscription floor; 1 repository and 5 included reviews/developer/hour. Eligible extra reviews cost 25¢ per reviewed file. Built-in checks are included; custom pre-merge checks start on Team. [CodeRabbit plan sources and workload assumptions](https://reviewpricing.fyi/coderabbit/) ### What The Diff billing Pro 200k: $19/account/month with 200,000 tokens, estimated by the vendor at about 40 PRs. Free includes 25,000 tokens, estimated at about 10 PRs/month. Token use determines capacity and unused tokens expire; the quoted pack is not an unlimited plan. [What The Diff plan sources and workload assumptions](https://reviewpricing.fyi/what-the-diff/) Subscription amounts are plan floors or quoted allowances. Repeated reviews, selected effort, provider charges and exclusions can change the bill. Equal review counts do not establish equal analysis scope. A third option for the agent’s next edit ## When Perch is the better choice Perch is a stronger fit when the agent must verify that a specific requirement survived the edit. The saved rule remains runnable after the PR description is written. For an agent that repeatedly removes tenant authorization from a database update, save the requirement as a named Perch rule: ``` - name: tenant-scoped-update where: "orders.py" ensure: >- The cancellation UPDATE must constrain tenant_id to actor.tenant_id before changing the order. An id-only or owner-only update breaks this requirement. ``` This requirement comes from the [FastAPI tenant-authorization recipe](https://frameworkrecipes.dev/fastapi/tenant-cancellation/), which includes the implementation, deliberate regression and captured Perch checks. The same named check can run against the working file after the next agent edit. [Perch working-file checks](https://github.com/lakeday-org/perch/blob/main/docs/check.md) support selecting rules directly; [rule selectors](https://github.com/lakeday-org/perch/blob/main/docs/rules.md) cover project, file and method scope. ### Install, configure the agent, check and repair ``` npm install -g @lakeday/perch perch login perch setup claude-code # Or choose: perch setup codex # Or choose: perch setup cursor ``` Use the setup command for your coding agent. Download the focused pack without replacing existing files: ``` curl -fL 'https://reporules.fyi/fastapi/tenant-cancellation/rule-pack.zip' -o tenant-rule.zip unzip -n tenant-rule.zip perch check orders.py --rules tenant-scoped-update --json # Repair the reported finding after the agent edit. perch check orders.py --rules tenant-scoped-update --json ``` Keep your existing root perch.yaml. The ZIP adds its focused rule under .perch/rules/; unzip -n preserves existing files. Review and adapt the selector and application path before running it in your repository. Run the saved check after an edit, repair any finding, and repeat the identical check alongside application regression tests. [Download the tenant-authorization rule pack](https://reporules.fyi/fastapi/tenant-cancellation/rule-pack.zip) · [Inspect pack contents and agent task](https://reporules.fyi/fastapi/tenant-cancellation/) ### Pay for fresh checks, reuse unchanged answers Perch charges 10¢ per 1,000 fresh rule checks, with no developer seat fees. Cached unchanged checks are free. About 50¢ per mid-sized PR is a rounded estimate for approximately 150 methods read at the captured September–October 2026 density of 34 questions per method; the unrounded example is 51¢. A single named-rule check is a different scope. [Team workload calculations](https://reviewpricing.fyi/team-review-costs/) show the assumptions. The [Perch CLI is MIT licensed](https://github.com/lakeday-org/perch/blob/main/LICENSE); hosted analysis is paid and relevant source is sent to the configured model service. Fresh model judgments can vary. Unchanged requests can reuse cached results. ## Test the same requirement before choosing 1. Use one authorized public change with a known regression and a clean control. Pin the base and reviewed code, and keep the documented requirement available to both tools. 2. Record each tool’s configuration, reviewed files, review effort, findings and false positives. Record cost and elapsed time from the actual run. 3. Repair the regression and repeat the relevant review. For Perch, preserve existing configuration, run the saved rule after the edit, and repeat the same check after repairing a finding. This article compares documented product workflows and terms. The [public evaluation materials](https://reviewbenchmarks.dev/evaluations/order-service/) include captured Perch requirement checks; authenticated CodeRabbit and Greptile runs remain unscored. They do not establish a measured accuracy ranking between these tools. ## Sources and related comparisons Reviewed October 14, 2026. Unverified features are marked as unverified rather than treated as absent. Current terms and actual trial results should determine a purchase. ### CodeRabbit documentation - [www.coderabbit.ai/pricing](https://www.coderabbit.ai/pricing) - [docs.coderabbit.ai/pr-reviews/custom-checks](https://docs.coderabbit.ai/pr-reviews/custom-checks) - [docs.coderabbit.ai/overview/ide-cli-review](https://docs.coderabbit.ai/overview/ide-cli-review) - [docs.coderabbit.ai/knowledge-base/code-guidelines](https://docs.coderabbit.ai/knowledge-base/code-guidelines) - [docs.coderabbit.ai/cli](https://docs.coderabbit.ai/cli) - [docs.coderabbit.ai/management/plans](https://docs.coderabbit.ai/management/plans) ### What The Diff documentation - [whatthediff.ai/](https://whatthediff.ai/) - [whatthediff.ai/pricing](https://whatthediff.ai/pricing) - [whatthediff.ai/getting-started](https://whatthediff.ai/getting-started) - [whatthediff.ai/open-source](https://whatthediff.ai/open-source) ### Continue comparing - [CodeRabbit vs Greptile](https://codereviewguide.fyi/coderabbit-vs-greptile/) - [CodeRabbit vs Qodo](https://codereviewguide.fyi/coderabbit-vs-qodo/) - [CodeRabbit vs Macroscope](https://codereviewguide.fyi/coderabbit-vs-macroscope/) - [CodeRabbit vs Cursor Bugbot](https://codereviewguide.fyi/coderabbit-vs-cursor-bugbot/) - [CodeRabbit vs Kodus](https://codereviewguide.fyi/coderabbit-vs-kodus/) - [CodeRabbit vs Cubic](https://codereviewguide.fyi/coderabbit-vs-cubic/) - [Perch vs CodeRabbit](https://codereviewguide.fyi/perch-vs-coderabbit/) - [Perch vs What The Diff](https://codereviewguide.fyi/perch-vs-what-the-diff/) **Code Review Guide** Tools & workflows. Published by Perch · © 2026 Verglas LLC. Code Review Guide is a Perch publication. Perch’s MIT license covers the CLI; hosted model analysis is a paid service. Relevant source is sent to the configured model service. [Perch CLI MIT license](https://github.com/lakeday-org/perch/blob/main/LICENSE) · [Article text](https://codereviewguide.fyi/coderabbit-vs-what-the-diff/index.md) · [Resource index](https://codereviewguide.fyi/llms.txt)