A software agency telling you to buy off-the-shelf sounds like a contradiction. It is not: building something a subscription already does well is the most expensive mistake in this whole decision, and a supplier who is paid to build has little incentive to talk you out of it.
What each one actually means
Off-the-shelf software is a product built for a broad market and sold to many customers: Xero or Sage for accounting, Shopify for e-commerce, HubSpot or Salesforce for CRM, Microsoft 365 for everything else. You configure it; you do not change it.
Bespoke (or custom) software is built for one organisation's requirements. You decide what it does, you own it, and nobody else's roadmap changes it under you.
When off-the-shelf is the right answer
- The process is standard. If thousands of businesses do it the same way, someone has already built it, tested it with all of them, and keeps it secure.
- You need it this month. A subscription is live in days; a build takes weeks at the very least.
- Compliance is somebody else's job. Payroll, tax and payments carry regulatory change that a vendor absorbs for every customer at once.
- You are early. Before you know exactly how your business works, flexible tools you can abandon cheaply beat software built around guesses.
When bespoke earns its cost
- The process is your advantage. If the way you quote, schedule, match or deliver is why customers choose you, forcing it into a generic tool erodes the thing you sell.
- You are paying to work around the product. Spreadsheets bridging two systems, staff re-keying data, plug-ins stacked to approximate one missing feature. Those costs are real and recurring; they just do not appear on the invoice.
- The software is the product. A startup cannot build its platform on someone else's — that is where an MVP comes in.
- Per-seat pricing stops scaling. Subscription costs grow with headcount; a bespoke system's running costs mostly do not.
Compare the cost over five years, not the first invoice
Off-the-shelf looks cheaper because its cost arrives monthly and bespoke's arrives up front. Put both over the same period before deciding. An illustrative example, not a quote:
| Five years, illustrative | Off-the-shelf | Bespoke |
|---|---|---|
| Up-front cost | Set-up and migration | The build |
| Recurring cost | Per-seat subscription × 60 months | Hosting, maintenance, support |
| Hidden cost | Workarounds, add-ons, price rises | Keeping the code maintainable |
| Example: 10 seats at £120 a month | £72,000 in subscriptions alone | Compare against the build quote plus running costs |
Neither total is automatically lower. What matters is doing the sum honestly, including the hours your team spends fighting the tool. For what a build itself tends to cost, see MVP costs in the UK.
The answer most businesses end up with: both
The common pattern is off-the-shelf for the commodity work and a small bespoke layer for what is specific to you, connected by integrations: your accounting stays in Xero, your payments in Stripe, and a custom system handles the workflow that is genuinely yours and talks to both.
That keeps the bespoke part small, which keeps it cheap to build and cheap to maintain, and it means you are never paying to rebuild something a subscription already does well.
Five questions to decide
- Do most businesses in your sector do this the same way?
- How many hours a week does your team spend working around your current tools?
- What will the subscription cost at twice your current headcount?
- Would changing this process hurt what customers choose you for?
- Who maintains it if the supplier disappears?
If the first answer is yes and the second is "not many", buy. If the fourth is yes, build — and make sure the answer to the fifth is "our own team, with the documentation".