SonarSource

Olivier Gaudin, Freddy Mallet and Simon Brandhof founded SonarSource in Geneva in 2008 around their open-source project Sonar, later renamed SonarQube. It runs static analysis over a codebase, counting code smells, duplication, test coverage and security issues, and expresses the result as estimated technical debt in hours.

The model is classic open core: a free community edition, paid tiers with more languages and security rules, plus a cloud service and an editor plugin. The company now calls itself simply Sonar and markets the idea of "Clean Code". The technical-debt figure is a rough guess, but it has secured budget for plenty of refactoring that would otherwise never have happened.