About Fallow

I spent most of my career as a frontend developer and tech lead. The bugs that cost me the most were never in one file. They were disagreements between files that never mention each other: two route segments named [id] and [slug] at the same level, an inject with no provider anywhere in the tree, a formatDate and a dateFormat written eighteen months apart by two people who never met.

The linter checks the file. TypeScript checks the types. The tests check what someone thought to describe. Nothing checks the codebase as a whole, so I built the tool that does. Fallow reads the whole module graph in under a second, which is fast enough for a pre-commit hook, so a finding arrives while the change is still in your head.

Coding agents made this more urgent. An agent sees a large repository through a keyhole, so it will happily write a fourth date formatter without knowing about the other three. Fallow gives the agent, and you, the view of the whole repository.

A static analyzer can prove that code is unreachable. It can never prove that reachable code actually runs. It is like a map of a city: it shows every road, but not which roads carry traffic. So Fallow Cloud adds the traffic. A beacon counts the calls to each function in production, per deployment, and every function gets one of three states: provably dead, reachable but cold, or alive. The middle state is where most of the weight of a mature codebase sits, and a static tool alone can never give it to you.

Fallow Cloud costs $20 per seat per month after a 30-day trial that needs no credit card. The pricing page has the details, and the product page shows how it works.

Fallow is bootstrapped. There are no investors and no venture capital, so I decide where Fallow goes, and the people I answer to are the people who use it. Fallow Cloud is the paid product, and it is how the company earns its money. The free scan stays free and open source under the MIT license.

The source of the free scan is public at github.com/fallow-rs/fallow, with every release, every release note and the issue tracker. The documentation is public too, in fallow-rs/docs. When Fallow reports something, you can read the code that decided it.

Early on, Fallow ran in a checkout without node_modules and concluded, with great confidence, that nearly everything was dead. Our own CI caught it. Since then every verdict carries a confidence level, because an analyzer that cannot say “I’m not sure” is not one you should delete code on.

Fallow Cloud is hosted in the EU. The API and database run in Amsterdam, and stored files and database backups stay in the EU. Some vendors process data outside the EU; the subprocessor list names each one and where it processes data.

The beacon sends call counts per function. It never sends argument values, return values, request data or user data. The network activity page lists every field that Fallow and Fallow Cloud send, and the privacy policy and the data processing addendum cover the rest.

• Legal name: Fallow B.V.
• Registration: Dutch Chamber of Commerce (KVK) number 42095869
• Founded: 2026, in the Netherlands
• Email: hello@fallow.tools. The contact page tells you what to send where.
• LinkedIn: Fallow on LinkedIn