Greptile builds AI agents that review and test pull requests for engineering teams. It has raised a $50 million Series B led by Menlo Ventures, at a $750 million valuation. Coding agents have sped up writing changes, while teams still have to decide whether a change works and whether it will break something for users. Greptile wants to be the independent check those changes pass through, including at companies that already use several coding agents, with the longer aim of automating validation well enough that complex changes can merge without a separate human review. The reviewer builds a graph of files, functions, and dependencies, then looks past the diff for logic bugs, security issues, and broken standards. TREX runs the pull request branch in a sandbox and attaches logs, screenshots, and traces to the comments it leaves. Every review includes a confidence score from 0 to 5, and teams can let Greptile auto-approve only a clean 5 out of 5. The company says it now reviews and tests more than 1% of all pull requests opened on GitHub each day, for more than 22,000 teams, including Nvidia, Coinbase, Decagon, and Vanta. Daksh Gupta, Soohoon Choi, and Vaishant Kameswaran founded Greptile in 2023 after studying computer science at Georgia Tech, then joined Y Combinator's Winter 2024 batch. Gupta is CEO and Choi is CTO. They started with a tool for asking questions of large codebases, then focused the product on pull request review and on running the code under review. The San Francisco team is still fewer than 50 people. The Series B follows a $25 million Series A led by Benchmark in September 2025.