The build vs buy software decision is one of the most consequential choices a growing business faces. Get it right and you unlock years of operational advantage. Get it wrong and you either waste six figures on software nobody uses, or you spend the next decade working around a tool that nearly fits.
This guide will help you think through the build vs buy software decision clearly. We have been building custom business systems since 2005 and have delivered over 50 Laravel applications, so we have seen this play out many times. But here is the thing: sometimes the right answer is a £50 per month SaaS subscription. We will tell you when that is the case too.
What Does Build vs Buy Actually Mean?
Build vs buy is the decision between developing custom software tailored to your specific business processes, or purchasing an existing product (SaaS subscription or off-the-shelf licence) that serves a similar function. Put simply, it is the custom software vs off-the-shelf question that every growing business eventually faces.
The question is not really about features. Feature lists are easy to compare. The real question is: how central is this system to the way your business operates, and what happens when you outgrow it?
This distinction is worth understanding before you look at a single price tag.
Commodity vs Core: The Key Distinction
Every business runs two types of system:
Commodity systems handle functions that are broadly the same across industries. Email, payroll, accounting, basic project management. These processes are well understood, heavily regulated, or simply not where your competitive advantage lives.
Core systems encode the way your business specifically operates. Your quoting logic, your client onboarding workflow, your production scheduling, your reporting dashboard. These are the systems where your business knowledge lives, and where off-the-shelf products force you into workarounds.
The build vs buy decision framework starts here. If the system is commodity, buy it. If the system is core, building deserves serious consideration.
Build vs Buy Software at a Glance
Before diving into the detail, this comparison captures the key differences between buying off-the-shelf software and building custom.
| Factor | Buy (SaaS / off-the-shelf) | Build (custom software) |
|---|---|---|
| Upfront cost | Low (monthly subscription) | Higher (development investment) |
| Time to deploy | Days to weeks | Weeks to months |
| Fit to your process | Generic, you adapt to it | Exact, it adapts to you |
| Ongoing cost (5 years) | Accumulates (often surprises) | Predictable maintenance |
| Customisation | Limited by vendor roadmap | Unlimited |
| Data ownership | Vendor-controlled | Fully yours |
| Switching cost | Can be very high | You own the code |
| Best for | Commodity functions | Core operations |
When Buying Off the Shelf Is the Right Answer
The custom software vs SaaS debate does not always favour custom. Let us be direct. For many business functions, buying is clearly the better choice. Building your own email system or accounting platform would be absurd.
A recruitment agency does not need a custom applicant tracking system. A small e-commerce business does not need a custom inventory platform. A consultancy does not need custom time tracking. Not unless their workflows are genuinely different from the standard.
Sometimes, the honest answer to the build vs buy software question is: buy it, and spend the money you saved on something that actually differentiates your business.
When to Build Custom Software
Knowing when to build custom software starts with recognising friction. Custom software earns its place when off-the-shelf products create workarounds that quietly cost you money. Here are the patterns we see most often after 20 years of building business systems.
The Real Cost of Build vs Buy Software
Most build vs buy software analyses compare the wrong numbers. They look at the subscription fee against the development quote and declare SaaS cheaper. That comparison misses most of the actual cost.
The Hidden Costs of Buying
A SaaS tool that costs £200 per month looks cheap. Over five years, that is £12,000 in subscription fees alone. But the real costs include:
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Per-seat pricing as you grow That £200 becomes £800 when your team doubles.
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Premium tier upgrades The feature you need is always on the next plan up.
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Workaround labour Staff time spent on manual processes the tool does not support (often 5-15 hours per week across a team).
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Integration costs Connecting tools together, maintaining those connections when APIs change.
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Training costs Every new hire needs training on a workflow that includes manual steps.
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Data export limitations When you need to leave, getting your data out can be expensive or impossible.
A realistic five-year cost for a mid-market SaaS stack often lands between £40,000 and £120,000 when you account for everything.
The Real Cost of Building
Custom software development in the UK typically costs between £15,000 and £80,000 for a well-scoped business application, with ongoing maintenance of roughly 10-20% of the build cost per year. According to the Standish Group's CHAOS reports, smaller, well-scoped projects have significantly higher success rates than large-scale builds.
A £40,000 build with £6,000 annual maintenance costs £70,000 over five years. That is often comparable to the true cost of the SaaS alternative, except you own the result, the system fits your process exactly, and your customer records belong to you.
The build vs buy decision framework should always compare total cost of ownership over five years, not sticker price against development quote.
A Six-Question Decision Framework
Before you decide whether to build or buy, work through these questions honestly.
Is this a commodity function?
If the answer is yes, buy. Do not build your own email system, payroll platform, or accounting software. These are solved problems with excellent products available.
How much time do workarounds cost each week?
Track it for a fortnight. Ask your team to note every time they say "the system cannot do that, so I..." If the answer is more than 10 hours per week across the team, the cost of buying is higher than you think.
What would it cost to leave your current vendor?
Check your data export options. Look at API access. Read the contract termination clauses. If leaving would take months and cost tens of thousands in migration, you are already more dependent than you may realise.
Where will you be in five years?
If your team will be three times the size, will per-seat pricing still make sense? If your processes will be more complex, will the off-the-shelf tool still fit? Project forward, not just sideways.
Can you clearly specify what you need?
Custom software requires clear requirements. If you cannot describe your ideal workflow in concrete terms, you are not ready to build yet. Use off-the-shelf tools to learn what you actually need, then build once you know.
Is this system a competitive advantage?
If the system encodes business knowledge that differentiates you from competitors, owning it protects that advantage. If it handles a function any business does the same way, ownership adds no strategic value.
Build vs Buy by Company Stage
The right answer changes as your business grows.
Early Stage
1-20 staff
Growth Stage
20-80 staff
Scale Stage
80-250 staff
Enterprise
250+ staff
Early Stage (1-20 staff): Default to Buying
Your processes are still evolving. You do not yet know what your core operations will look like at scale. Use SaaS tools generously. Pay attention to where friction appears.
Growth Stage (20-80 staff): Identify Your Friction Points
By now you know which processes define your business and which are commodity. Start quantifying the cost of workarounds. Begin scoping custom builds for your one or two core systems.
Scale Stage (80-250 staff): Build Your Core Systems
The cost of workarounds at this scale is substantial. Per-seat SaaS pricing becomes painful. Custom software that encodes your operational knowledge pays for itself within two to three years.
Enterprise (250+ staff): Optimise Ownership
You likely need a mix: custom core systems, best-of-breed SaaS for commodity functions, and a custom integration layer connecting everything.
The Third Option: Buy Commodity, Build Core
The best approach to the build vs buy software question is rarely pure build or pure buy. Most businesses that get this right follow a pattern.
This hybrid approach gives you the speed and cost efficiency of SaaS for functions where it genuinely makes sense, with the control and fit of custom software where it matters most.
The integration layer is often the most overlooked piece. It is the glue that lets your custom customer records system talk to your accounting software without manual data entry, and lets your operations dashboard pull from every source automatically.
How We Approach Build vs Buy Decisions
When a client asks us whether to build or buy, we start with a discovery conversation rather than a proposal. We ask the six questions above. We map their systems. We identify which are commodity and which are core.
Roughly a third of the time, our recommendation is "do not build this, buy X instead." We would rather give honest advice than sell a project that should not exist. That is how we have kept clients for 15 or 20 years rather than cycling through projects.
When building is the right answer, we scope it carefully, build iteratively, and make sure the client owns everything: the code, the data, the infrastructure. No lock-in, no ongoing dependency.
That approach has served us well since 2005, building on Laravel and PostgreSQL. Over 50 custom applications later, the pattern holds: honest assessment first, then build only what genuinely needs building.
If you are wrestling with a build vs buy software decision, we are happy to talk it through. No pressure, no obligation. Sometimes a 30-minute conversation saves months of heading in the wrong direction.
Frequently Asked Questions
What is the build vs buy decision in software?
The build vs buy decision is the choice between developing custom software specifically for your business processes, or purchasing an existing product (typically a SaaS subscription or off-the-shelf licence) that serves a similar function. The right answer depends on whether the function is a commodity process or a core competitive advantage.
How do you calculate the total cost of ownership for build vs buy?
Compare five-year costs for both options. For buying, include subscription fees, per-seat scaling costs, integration expenses, workaround labour, and training. For building, include development cost, annual maintenance (10-20% of build cost), hosting, and any future enhancements. Most businesses underestimate the true cost of SaaS by 40-60%.
When should a small business build custom software?
Small businesses should generally buy off-the-shelf tools until they clearly understand their core processes and can specify exactly what they need. The exception is when an off-the-shelf product creates significant friction in a process that is central to how the business operates and competes.
Is custom software more expensive than SaaS?
Not necessarily over time. While custom software has higher upfront costs, the total five-year cost is often comparable to or lower than a SaaS stack when you include per-seat pricing growth, workaround labour, integration costs, and premium tier upgrades. Custom software also provides better data ownership and process fit.
What are the risks of building custom software?
The main risks are unclear requirements (leading to scope creep), choosing the wrong development partner, and underestimating ongoing maintenance needs. These risks are mitigated by thorough discovery, iterative development, and working with experienced teams who will tell you honestly when buying is the better option.
Let's Talk Through It
If you are wrestling with a build vs buy software decision, we are happy to talk it through. No pressure, no obligation. Sometimes a 30-minute conversation saves months of heading in the wrong direction.
Book a discovery call →