Fifteen years ago, "business software" usually meant a server humming in a back room, an IT person on call, and an upgrade cycle everyone dreaded. Today, most small and mid-sized businesses run their operations almost entirely on software they never installed, on hardware they'll never see. That shift happened quietly, one subscription at a time.

What actually changed

Three things had to happen together for SaaS to take over from in-house systems:

What businesses actually got out of it

The appeal isn't really "cheaper," even though it often is. It's speed and reversibility. You can start using a CRM this afternoon and cancel it next quarter if it's wrong for you — something that was unthinkable when adopting new software meant a six-month implementation project.

The real cost of old-style business software was never just the license fee. It was the year of internal disruption every major system change caused. SaaS shrank that disruption from months to days.

Where the model starts to strain

SaaS isn't free of trade-offs, and they show up predictably as a company grows:

So when does custom still make sense?

Subscribing is the right default for most businesses, most of the time. Building custom software still wins in a few specific, recognizable situations:

The practical takeaway: SaaS won by removing the cost of trying something and failing. That's still true. The businesses who eventually move to custom software aren't rejecting that logic — they've usually just outgrown what a shared, one-size-fits-most product can flex to.

We wrote a longer, more practical checklist on exactly this decision — see Build vs. Buy: When Custom Software Actually Beats Off-the-Shelf SaaS.