/dev/fast builds Review, an open-source desktop app for code review in the era of coding agents. The buyer decision is whether a team needs architecture-level understanding of a large diff and its agent trace, rather than another line-by-line reviewer or a summary bot.
What it does
Review presents interactive visualizations, diffs, and agent trajectories in one review surface. The public demo describes sequence and database diagrams, chat with the authoring agent, and trace links that let a reviewer connect an implementation decision back to the change. The broader /dev/fast roadmap also names local trajectory storage, merge rules, code storage, and programmable CI (Review homepage; /dev/fast about).
| Fact | What the public sources say |
|---|---|
| Buyer | Engineers and staff reviewers working with AI-generated or very large changes |
| Core product | Open-source macOS Review app for diffs, architecture views, agent chat, and trajectories |
| Review boundary | Review helps a human understand and critique code; it does not claim to replace approval |
| Availability | Desktop beta; hosted Review is described as coming soon |
| Founders | Sid Menon, Ketan Agrawal, Milan Bhandari, and Alex Iansiti |
Why it fits
The product addresses a real shift in review work. When an agent can produce a thousand-line change in minutes, reading every line is both expensive and insufficient; the reviewer needs to understand the architecture the change touches, the assumptions the authoring agent made, and whether the resulting system still behaves coherently. Interactive diagrams and trace-linked context are aimed at that decision.
The tradeoff is local workflow and team adoption. The current public app runs on macOS, and the hosted collaboration layer is not yet described as generally available. A buyer should resolve repository permissions, secret handling, trace retention, generated-diagram accuracy, monorepo scale, CI integration, and whether a review artifact can be shared with the rest of the team. Pricing was not published in the reviewed sources.
The founders bring direct systems and AI-tooling context. YC describes Menon and Bhandari as former Palantir infrastructure engineers, Agrawal as a Robust Intelligence and Snowflake ML engineer, and Iansiti as a Pinterest and Flowcode engineer (YC company profile).
Short version: /dev/fast is worth trying on the hardest agent-generated change in a repository. It is most useful when a reviewer needs to see what the code means, not merely whether a linter passed.
Sources checked — 2026-09-19
Cohort context
/dev/fast is listed in Winter 2026. In our 2026-09-18 directory snapshot, 126 of 199 listed companies in that cohort have YC’s primary industry label B2B (63.3%). This is a current-directory comparison, not an original intake count or a performance ranking. Nine-cohort dataset.
Public website snapshot
Observed 2026-09-19 16:19 UTC in raw homepage HTML. This records visible metadata and advertised links, not agent execution or product quality.
| Signal | Homepage observation |
|---|---|
| Product description metadata | Observed |
| Canonical link | Not observed in this response |
| H1 or H2 heading | Observed |
| Typed structured data | Not observed in this response |
| Docs/developer link | Not observed in this response |
| Pricing link | Not observed in this response |
| llms.txt link | Not observed in this response |
| Markdown alternate | Not observed in this response |
Public observations · Collection method. Missing links here do not establish that a capability or file is absent elsewhere.
