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Merlin AI Code Review
What Merlin AI Code Review is
Merlin AI Code Review reviews pull request diffs and posts inline comments without sending code to a third-party SaaS. Comments identify bugs, security, style, and performance issues at file and line level, sorted by severity. Security checks include OWASP Top 10 analysis, secret detection, and Snyk dependency scanning. Merlin works with GitHub, GitLab, Bitbucket, Azure DevOps, and Gitea. Its listed AI backends include Claude, GPT-4o, Gemini, Bedrock, Ollama, and Claude Code CLI. It can index a codebase and earlier review comments to retrieve relevant snippets before AI calls; embeddings run locally through Ollama. The product is presented as a Rust single binary for CI pipelines, with no Merlin server or account required. The maker says code stays on the user's servers and describes an Ollama and local Qdrant setup for offline use with no external calls. Merlin is MIT-licensed and free forever, but users bring their own AI API key and pay their AI provider for token usage. The maker describes it for solo developers, startups, open-source teams, regulated banks, and air-gapped defence labs.
Who it suits
Merlin may suit development teams that want pull request reviews within their own infrastructure, including teams using supported Git hosts. It is also positioned for solo developers and organizations with regulated or air-gapped environments.
What it does well
- Posts inline comments at file and line level.
- Security checks include secret and dependency scanning.
- Supports five listed code-hosting services.
- Can use local Ollama embeddings and local Qdrant.
- MIT-licensed with no per-seat fee.
What to know first
- Users must supply an AI API key.
- AI provider token charges still apply.
- No Merlin server or account is provided.
- Offline setup is described using Ollama and local Qdrant.
Limits
The Free forever plan costs nothing and has no per-seat fee, but users pay their AI provider for token usage. For offline use, the maker describes using Ollama with local Qdrant and no external calls.
Plans
| Plan | Billed and limits | Price |
|---|---|---|
| Free forever | MIT license · No per-seat fee · Bring your own AI API key; provider token charges apply | Free |
As merlin-review.com lists them, read 3 Oct 2026. The maker's own page has the final word.
Getting started
- Open the Merlin website.
- Use a Linux environment for the self-hosted deployment.
- Run the Rust single binary in a CI pipeline.
- Connect a supported code host: GitHub, GitLab, Bitbucket, Azure DevOps, or Gitea.
- Provide an AI provider API key, or configure Ollama for local AI use.
Verdict
Merlin offers self-hosted pull request review with configurable AI backends and security scanning. The software is free, but users arrange their own AI access and cover provider token charges.
Questions
How much does Merlin AI Code Review cost?
The Free forever plan costs nothing under an MIT license, with no per-seat fee. Users bring their own AI API key and pay the provider for token usage.
Does Merlin have a free plan or trial?
It has a free forever plan. A free trial is not offered.
Which platforms and code hosts does Merlin support?
It is listed for Linux and self-hosted deployment. Supported code hosts are GitHub, GitLab, Bitbucket, Azure DevOps, and Gitea.
Which AI backends can I use?
The listed backends are Claude, GPT-4o, Gemini, Bedrock, Ollama, and Claude Code CLI.
Is Merlin open source, and who makes it?
Merlin is MIT-licensed. The site credits Arunachalam Kalimuthu as its maker.
Facts from Merlin AI Code Review's own pages
- AI providers
- The site lists Claude, GPT-4o, Gemini, Bedrock, Ollama, and Claude Code CLI as supported AI backends. · merlin-review.com, 3 Oct 2026
- Audit logs
- The maker says every AI call can be logged locally and describes this as HIPAA/SOC2 friendly. · merlin-review.com, 3 Oct 2026
- Autonomous agent
- Its ReAct-loop agent can plan multi-step tasks and use the slash commands, RAG search, comment posting, and PR information tools. · merlin-review.com, 3 Oct 2026
- Context-aware reviews
- Merlin can index a codebase and past review comments, then retrieve relevant snippets before AI calls; embeddings run locally via Ollama. · merlin-review.com, 3 Oct 2026
- Deployment
- The product is presented as a Rust single binary that runs in a CI pipeline, with no Merlin server or account required. · merlin-review.com, 3 Oct 2026
- Git integrations
- The site says Merlin works with GitHub, GitLab (cloud and self-hosted), Bitbucket, Azure DevOps, and Gitea. · merlin-review.com, 3 Oct 2026
- Intended users
- The maker describes it for solo developers, startups, open-source teams, regulated banks, and air-gapped defence labs. · merlin-review.com, 3 Oct 2026
- License and cost
- Merlin is MIT-licensed and free forever; users supply their own API key and pay their AI provider for token usage. · merlin-review.com, 3 Oct 2026
- Maker
- The site credits Arunachalam Kalimuthu as the maker. · merlin-review.com, 3 Oct 2026
- Purpose
- Merlin reviews pull request diffs with configurable AI and posts inline comments without sending code to a third-party SaaS. · merlin-review.com, 3 Oct 2026
- Review comments
- It posts file- and line-level comments about bugs, security, style, and performance, sorted by severity. · merlin-review.com, 3 Oct 2026
- Security and privacy
- The maker says source code stays on the user's servers and describes an Ollama plus local Qdrant configuration for offline use with zero external calls. · merlin-review.com, 3 Oct 2026
- Security features
- Security scanning includes OWASP Top 10 analysis, secret detection, and Snyk dependency scanning. · merlin-review.com, 3 Oct 2026
- Support
- The maker directs users to open an issue, start a discussion, or contact the team directly for feedback. · merlin-review.com, 3 Oct 2026
Where Merlin AI Code Review stands on Freedom251
- AI Code Review Tools#16 of 48