Ian MacKinnon, CTO of Later and Mavrck, shares lessons learned building Later from founding to success to acquisition – and from the startups that weren’t so fortunate. We discuss early engineering practices that paid off, approaches for moving fast and tolerance for breaking (small) things in that pursuit, the pros and cons of PaaS platforms like Heroku, the insurmountability of building the wrong thing, the virtues of boring tech stacks, and Later’s successes using GPT-4 to migrate and modernize legacy codebases.