Google’s Code Quality Practices and the Myth of Code Age vs. Quality

This piece collects responses from a current Google engineer, Jeremy Hoffman, and a former Google employee, Dima Korolev, to address a Quora question about the relationship between a company's age and its code quality, specifically focusing on Google.

Jeremy Hoffman emphasizes that Google’s code quality is exceptionally high, attributing it to a robust software‑engineering culture that includes:

Code reviews : Every change must be approved by the code’s “owner,” encouraging substantial revisions rather than superficial approvals.

Strict style‑guide enforcement : Language‑specific readability standards prevent the use of complex or error‑prone C++ features such as static or global variables in classes.

Team‑wide commitment to maintaining core libraries and improving tooling.

Active “code‑health” working groups that focus on overall repository quality.

Release practices without external deadlines , allowing engineers to prioritize correctness over rushed delivery.

“Fixits” : Periodic events where engineers replace legacy or problematic code (e.g., the deprecated CruftMap class) across the codebase.

Testing culture : Near‑100% unit‑test coverage, continuous integration, and the famous “Testing on the Toilet” practice.

The author notes that while some older Google code becomes isolated and harder to maintain, the overall trend at Google is an improvement in code quality over time due to these systematic practices.

Dima Korolev, a former Google employee, concurs that Google’s code quality is very high, though he observes that maintaining strict standards can be viewed as overly rigorous after leaving the company. He also mentions that code quality depends on many factors, including engineer attitudes and reward systems, but acknowledges that Google’s approach has historically been effective.

Overall, the discussion suggests that code quality at Google improves with time thanks to disciplined engineering processes, contradicting the notion that code quality necessarily declines as code ages.