Fallow

About Fallow

Fallow is deterministic codebase intelligence for TypeScript and JavaScript. It gives developers, CI, and AI agents one factual picture of a codebase before a change ships. AI can write plausible code, but it has no reliable way to check whether a change made the codebase better or worse. Teams paper over that with prompts like "be careful" and "act like a senior engineer." The result is AI slop: duplication, dead code, broken boundaries, and changes nobody fully trusts. Fallow puts engineering standards inside the agent loop instead of in wishful prompts. An agent, a developer, or a CI pipeline calls Fallow through the CLI, MCP, or hooks and gets deterministic, reproducible answers about a codebase: what is dead, what is duplicated, what is risky, what is drifting, and what actually runs in production. Those facts drive safer refactors, more trustworthy reviews, and changes a human can stand behind. Fallow ships as two layers on one pipeline. The open-source core is free, Rust-native, sub-second, and zero-config, with support for every major framework and surfaces across the CLI, LSP, MCP, GitHub Actions, and VS Code. Fallow Runtime, the paid layer, adds production execution evidence and team guardrails: hot paths, cold code, runtime-backed review, shared history, and alerts. Static analysis is free and open source. Runtime intelligence is the paid team layer. Why now: AI made code cheap to produce and expensive to trust. Every team adopting coding agents inherits the same problem, and no incumbent owns the answer yet. Fallow is building that category, for the humans, CI pipelines, and agents that all need the same factual picture of a codebase before a change lands. Learn more at https://fallow.tools