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Martian scores code review bots on whether a developer actually changed the code
Code Review Bench reconstructs the timeline of 16,017 open source pull requests and publishes precision and recall beside every F1. The top five tools sit within five points of each other, on samples of very different size.
The Engineer · Build desk

What happened
- Every ranking of AI code review tools in the search results has an owner: DeepSource's listicle puts CodeRabbit first while DeepSource sells a code-quality product, and CodeAnt AI's own 2026 roundup rates CodeAnt AI best overall.
- Martian, an AI research lab, runs Code Review Bench, which reconstructs the timeline of real open source pull requests and counts a bot suggestion as a hit only when a developer acted on it.
- The live leaderboard has scored 16,017 pull requests across 14 tools, including platform-native Copilot and Cursor, standalone reviewers such as Greptile and Qodo, and coding agents Claude and Devin.
- On overall F1, Cubic Dev AI leads at 65.7 percent, ahead of GitHub Copilot at 63.9, Claude at 62.5, Greptile at 61.9 and CodeRabbit at 60.8.
- The per-tool samples are uneven: Copilot was scored across 767 pull requests, CodeRabbit across 2,109 and Qodo across 2,208.
Compiled by The EngineerSomething wrong?How this is made
Why it matters
- constraint A team whose reviewers ignore more bot comments than these open source maintainers did should expect lower precision from the same tool, because adoption is what the score counts.
- capability The pipeline is MIT-licensed code, so a team can rerun the scoring against its own merged pull requests, where the developer who acted is one of its own.
- decision The leaderboard can thin a candidate list for trials, but platform fit, self-hosting and per-seat cost against volume stay off it, so the purchase still turns on pricing pages that move monthly.
- precedent A scoreboard nobody commissioned gives a buyer something to hold a vendor list against, including the 13 rows a vendor's own page will not print.
The F1 column is not an independent measurement. Cubic Dev AI's 72.9 precision and 59.8 recall give 2 x 72.9 x 59.8 / (72.9 + 59.8) = 65.7, the F1 printed beside them, and the same harmonic mean reproduces the published F1 on every row where all three numbers appear [21][25]. Read the two input columns and you have the row. Read F1 alone and you cannot tell whether a tool got there by commenting rarely and well, or often and roughly.
Everything on the board rests on what "acted on" means. Martian reconstructs each review timeline from bot suggestion to developer response to the code change that landed, and a suggestion counts as a hit only when a developer acted on it [5]. A comment that correctly flagged a race condition and got ignored is a false positive under that rule. Precision here is a measurement of the bot and of the maintainers who received its comments. The post explains how a hit is counted; it does not describe how the denominator for recall is built [30].
Greptile has the highest precision in the group at 80.3 and a recall of 50.4, a gap of 29.9 points [12][22]. When it comments, developers usually act on it, and it leaves more issues unreported than the other leaders. Which of those two failures is cheaper depends on your gate. If a human triages every bot comment before the author sees it, recall is the scarce thing; if the bot posts straight to the pull request and the team has learned to skim it, precision is.
For the ordering to transfer, your reviewers would have to act on bot comments at roughly the rate the open source maintainers in this corpus did, and your pull requests would have to carry a similar mix of defects [20]. The post is direct about the first half: "Your closed codebase, compliance rules, and review culture are not that sample." [19]
Copilot's 63.9 rests on 767 pull requests, about 4.8 percent of the 16,017 the leaderboard has scored [23]. Qodo's 58.9 rests on a sample nearly three times as large [29]. Copilot's row has the most room to move as the corpus grows.
Set that against the ranking CodeAnt AI published. Its own 2026 roundup rates CodeAnt AI best overall, in a list it wrote, and its advertising carries a "300K-PR" figure that counts volume and not accuracy [2]. On the open leaderboard the tool scores 72.3 precision and 38.2 recall for an F1 of 50.0, the lowest of the seven rows the post lists [15][24].
What to watch
- Whether Copilot's 767-pull-request sample grows and its 63.9 F1 keeps second place as the corpus expands past 16,017.
- Whether Martian publishes how the recall denominator is constructed, since every recall figure on the board depends on it.
- Whether any vendor listicle begins citing Code Review Bench rows other than its own.