There is a moment in every successful SaaS product's life when the architecture that got it to market becomes the architecture that threatens to kill it. It usually arrives somewhere between the first enterprise customer and the second. The symptoms are always the same: deployments slow to a crawl, on-call rotations become relentless, and the team spends more time working around the system than building on top of it.
We've seen this arc play out three times in the last two years across three very different products — a logistics intelligence platform, a B2B analytics SaaS, and a document automation tool. In each case, the same five categories of architectural decisions created the crisis. In each case, they had seemed entirely reasonable at the time they were made.