When Should a Business Build Custom Software Instead of Buying SaaS?
“Should we build this ourselves or just buy a SaaS tool?” is one of the most common questions I get from founders and operations leaders. It’s also one of the easiest questions to answer badly, because both sides of the argument sound reasonable in isolation. SaaS is faster and cheaper up front. Custom software is more flexible and fully owned. Neither statement is wrong — but neither is a complete answer either.
The Default Should Be SaaS
I say this as someone who builds custom software for a living: for the vast majority of business needs, an existing SaaS product is the right call. Accounting, email marketing, basic CRM, HR systems, project tracking — these are solved problems with mature, well-supported tools built by teams whose entire job is maintaining and improving that one product. Building a custom version of any of these is almost always a waste of budget and engineering time that could go toward whatever actually differentiates the business.
The mistake I see most often isn’t businesses building too much custom software. It’s businesses either building custom software for commodity problems, or sticking with an ill-fitting SaaS tool for a problem that’s actually core to how they operate.
When Custom Software Starts to Make Sense
1. The Process Is Genuinely Unique to the Business
If a workflow is a real source of competitive advantage — the way a business fulfills orders, prices a service, or routes work to the right team member — forcing that process into a generic SaaS tool’s rigid structure often means reshaping the business around the software instead of the other way around. That’s backwards, and it usually creates friction that shows up months later as workarounds, spreadsheets, and manual double-entry.
2. You’re Paying for a Lot of Features You Don’t Use
Many SaaS platforms price around an all-in-one bundle. If a business only needs 20% of what a platform offers, but is locked into an enterprise tier to get the one feature it actually needs, the economics can flip over a two-to-three-year horizon. This is especially true as user counts or transaction volume grow, since SaaS pricing tends to scale with usage.
3. Integration Requirements Are Extensive
Some businesses need a system to sit in the middle of several other systems — pulling data from inventory, pushing to accounting, syncing with a customer portal. If no off-the-shelf tool integrates cleanly with that specific combination of systems, a custom solution (or a well-built integration layer) often ends up more reliable than duct-taping several SaaS tools together with fragile automations.
4. Data Ownership and Long-Term Control Matter
With SaaS, you’re renting access to your own operational data, subject to another company’s pricing changes, feature roadmap, and business continuity. For some businesses that’s a non-issue. For others — particularly those where the software is becoming a core part of the product or service being sold — owning the system outright is a legitimate long-term strategic consideration.
A Middle Path: Build on Top of Existing Platforms
It’s rarely all-or-nothing. A common and often underrated approach is building custom functionality on top of an existing platform rather than from scratch — for example, extending WordPress or a similar system with custom functionality, rather than either accepting a generic SaaS tool or building an entire application from zero. This captures a lot of the speed and lower cost of an existing platform while still allowing the specific, differentiating parts of the workflow to be built exactly the way the business needs them.
A Hypothetical Example
Consider a wholesale distributor with a pricing structure that varies by customer tier, order volume, and seasonal contracts. A generic e-commerce or CRM platform will likely struggle to represent that pricing logic without significant workarounds. In that scenario, a relatively small custom module — handling just the pricing and quoting logic — layered on top of an existing platform for everything else, is usually far more cost-effective than either forcing the SaaS tool to do something it wasn’t built for, or building an entire custom platform from the ground up.
How to De-Risk the Decision Before Committing
Because this decision is hard to fully reverse once significant budget has gone into a custom build, it’s worth de-risking it before committing. Start by mapping the specific workflow in detail — not a general description, but the actual steps, exceptions, and edge cases — and testing it against two or three leading SaaS tools to see exactly where they fall short, rather than assuming they will. Sometimes a SaaS tool handles 80% of a “unique” process just fine, and the truly custom part is much smaller than it first appeared, which changes the economics considerably.
It’s also worth talking to businesses of a similar size and shape about what they use, since the honest answer is often more useful than a vendor’s sales pitch. And if custom development does turn out to be the right call, consider whether a smaller pilot — automating just the highest-friction part of the process — can validate the approach before committing to building the entire system.
What Hybrid Ownership Looks Like in Practice
Some businesses find the most durable answer isn’t a single decision made once, but a policy applied consistently: default to SaaS for every new need unless a specific, documented case can be made for building custom, and revisit that judgment periodically as the business and the surrounding SaaS landscape both change. A tool that was the obvious buy-not-build choice three years ago might no longer be, either because the business’s needs have become more specific, or because a better SaaS option has since emerged. Treating “build vs buy” as a decision revisited occasionally, rather than a one-time verdict, keeps the business from being locked into a choice that made sense once but no longer fits.
The Real Question to Ask
Instead of “build or buy,” the more useful question is: “Is this specific piece of the business generic, or is it where we actually create value?” Generic problems should almost always be bought. The parts of the business that are genuinely distinctive are where custom development tends to earn back its cost.
If you’re trying to work through that decision for a specific project, it’s a conversation worth having before any code gets written. I cover this kind of scoping work as part of technology consulting, and you can see examples of custom platforms built this way in the project portfolio.