Custom Development or SaaS? A Decision Checklist

Sooner or later, every owner who takes digitalisation seriously faces this afternoon: two proposals on the desk. One is a custom development quote — timeline in months, more zeros than expected. The other is a SaaS subscription — live today, billed yearly, a fraction of the price. Each salesperson has a line ready: 'template software will never fit your business' versus 'custom development is a bottomless pit'.

Both lines contain some truth, and both come with an agenda. This article lays the decision variables out one by one, and ends with a seven-question checklist you can take straight into your next selection meeting.

First question: is this process industry-standard?

Attendance, expense claims, invoicing, inventory, basic customer records — these processes look much the same across thousands of companies, and mature SaaS products have refined the common practice over many rounds. For standard processes, buy off the shelf. There are few exceptions.

The usual objection is 'we do things differently here'. It deserves a calm follow-up: is that difference a deliberate choice, or an inherited habit nobody can explain? Commissioning custom software around an unexamined habit means paying money to set a bad habit in concrete. The reverse is also true: adopting a standard SaaS and following its default flow often doubles as a free process health check — and frequently runs smoother than the old way.

Second question: is this step where you actually differ?

Only one kind of step earns custom development: the step that constitutes your reason for winning in the market. Your pricing logic is too intricate for competitors to copy; your delivery process is why clients choose you; a scheduling method nobody else has keeps your costs below the industry's. Forcing those steps into a standard product means sawing off your own longest plank.

The test is simple. Imagine this step done exactly the way your competitors do it — would customers leave? If not, it is not differentiation, and a standard product will do. If yes, it may deserve the investment.

Do not skip the four practical constraints: data, budget, time, people

Data sensitivity and compliance. Some industries dictate where data must reside; some major clients write into contracts that their material may not leave a specified environment. These constraints act as vetoes: either pick a product that supports private deployment, or build — ordinary SaaS is simply out.

Budget and go-live date. SaaS works this week; custom builds run in months, before counting the inevitable rounds of requirement changes. If the business window is right in front of you, put a standard tool in place first. Do not let the perfect system cost you the season.

Long-term maintenance. Delivery day is not the end of a custom system — it is the beginning. Servers need minding, faults need fixing, and every business change ripples into code changes. Without someone in-house who can work with engineers, a custom system usually ends up as the thing nobody dares touch, with the business dragged along by software nobody dares change.

Count the full bill: the quote is only the down payment

The most common mistake in cost comparison is putting the one-off custom quote next to the SaaS annual fee. The real cost of custom software has at least four layers: the build fee (the down payment), yearly maintenance, iteration whenever the business shifts, and the layer most often ignored — key-person risk. The vendor's team changes, the lead engineer leaves, the contractor pivots, and your system slowly becomes a black box nobody can read.

SaaS inverts that structure: you pay every year, but every year is list-priced, with no surprise 'this change needs to be re-scoped'. Run the numbers over five years and the answer is often the opposite of intuition.

The costliest mistake: a 100% custom system for a 10% need

The most expensive pattern in real-world selection goes like this: standard SaaS covers nine-tenths of the workflow, one-tenth will not fit, so the company decides to custom-build the whole thing. For that one-tenth, it gives up the nine-tenths a mature product has spent years polishing — and shoulders all future maintenance on top.

The pragmatic route is hybrid: SaaS as the base, APIs in between, a thin custom layer on top. Standard steps go to the standard product; the piece that will not fit becomes a small custom module that exchanges data with the main system through its API. This is exactly why an open API counts as a hard test in What Is SaaS — it decides whether you have the option of patching a small piece at all.

Seven questions to walk the decision through

Facing a concrete choice, run these in order:

1. Is this process an industry-standard practice, or genuinely unique to us?
2. If we did this step exactly the way competitors do, would customers leave?
3. Are there hard constraints on data residency or compliance that veto one option?
4. When does the business need this live? Can it wait for a custom build?
5. Over five years — including maintenance, iteration and staffing — what does each route really cost?
6. Is there someone in-house who can own, accept and maintain a custom system long term?
7. Could a hybrid — SaaS plus a thin custom layer — get us running first?

After the seven questions, most cases answer themselves: buy for standard processes, consider building only for true differentiation, and when unsure, start with the hybrid route and verify in small steps. For keeping the resulting toolkit coherent, the four principles in Tool Selection for a Ten-Person Team apply here too.