Choose off-the-shelf SaaS when a mainstream product covers most of your workflow and your process is not what sets you apart. Choose custom software when your workflow is a competitive advantage, when you are stitching several tools together by hand, or when per-seat fees keep climbing. The scoring checklist below turns that judgement into a number.
Most businesses do not need to pick one side for everything. The useful question is which parts of the business to rent and which to own.
What is the real difference between custom software and SaaS?
SaaS is software you rent and adapt to; custom software is software you own and adapt to you. Everything else (cost, speed, risk) follows from that.
| Factor | Off-the-shelf SaaS | Custom software |
|---|---|---|
| Who it is designed for | Thousands of businesses at once | One business: yours |
| Time to start | Today | Weeks to months (an MVP typically 8–16 weeks) |
| Upfront cost | Little or none | A build budget (an MVP typically US$15k–50k) |
| Ongoing cost | Subscription, usually per user per month | Hosting plus roughly 15–25% of build cost per year in maintenance |
| Fit | You change your process to match the tool | The tool matches your process |
| Roadmap | Set by the vendor | Set by you |
| Data | Stored on the vendor's terms | Stored where you choose |
| Leaving | Export what the vendor allows | Move hosting or developers whenever you like |
Neither column is "better". A SaaS accounting package is almost always the right call. A pricing engine that encodes how you win jobs probably is not something to rent.
How does the scoring checklist work?
Score ten criteria from 0 to 2, multiply by the weight, and add up the total out of 40. A higher score points towards custom software; a lower score points towards SaaS.
Score each line honestly for the specific process you are considering, not the whole business:
- 0 means the statement is not true for you.
- 1 means it is partly true.
- 2 means it is clearly true.
| # | Criterion | Weight | What a "2" looks like |
|---|---|---|---|
| 1 | The process is a competitive advantage | 3 | Customers choose you partly because of how you do this |
| 2 | No product covers 80% of the need | 3 | You have trialled the leading tools and each misses something essential |
| 3 | Staff re-key data between tools | 2 | Someone copies the same information between systems every day |
| 4 | Per-seat costs are rising fast | 2 | Subscription spend grows every time you hire |
| 5 | You need control of your data | 2 | Contracts, regulation or customers require specific storage or handling |
| 6 | Integrations are critical | 2 | The process only works if several systems share data reliably |
| 7 | The process is stable | 2 | It has not changed much in the last year and is unlikely to soon |
| 8 | You can fund maintenance | 2 | You can budget 15–25% of the build cost every year |
| 9 | Someone can own the project | 1 | A decision-maker can give a few hours a week during the build |
| 10 | You plan to sell or license it | 1 | The software could become a product or add value to the business |
Maximum score: rows 1–2 give up to 12 points (2 rows × weight 3 × score 2), rows 3–8 up to 24, and rows 9–10 up to 4, giving 40 in total.
How should you read your score?
Under 15, buy; 15 to 25, consider a hybrid; over 25, custom software is likely worth a proper discovery. Treat these as guide rails, not rules.
- 0–14: Buy SaaS. The fit problem is small or the process is still moving. Configure a good product, train the team, and revisit in a year.
- 15–25: Hybrid. Keep SaaS for the standard parts and build a custom layer where it hurts most, usually an integration, a portal or a dashboard.
- 26–40: Build, carefully. The case for custom is strong. Run a discovery phase, scope a lean first version and get a fixed price.
Two rows can override the total. If row 7 scores 0 (the process keeps changing), wait before building anything. If row 8 scores 0 (no maintenance budget), do not build; unmaintained software becomes a liability.
What does a worked example look like?
Here is an illustrative scoring for a hypothetical 20-person property management company deciding how to handle maintenance requests. The numbers are invented for the example, not drawn from a client.
| # | Criterion | Score | Weighted |
|---|---|---|---|
| 1 | Competitive advantage | 2 | 6 |
| 2 | No product covers 80% | 1 | 3 |
| 3 | Re-keying data | 2 | 4 |
| 4 | Rising per-seat costs | 1 | 2 |
| 5 | Data control | 1 | 2 |
| 6 | Critical integrations | 2 | 4 |
| 7 | Stable process | 2 | 4 |
| 8 | Maintenance budget | 1 | 2 |
| 9 | Project owner | 2 | 2 |
| 10 | Product potential | 0 | 0 |
| Total | 29 |
At 29, this company sits in "build, carefully". But row 2 scored only 1: an existing tool comes close. A sensible next step would be a short discovery to test whether a custom tenant portal connected to their existing accounting and property software (a hybrid) delivers most of the value for less than a full build.
Why is the hybrid option so often the right answer?
Most businesses get the best return by buying commodity software and building only the thin layer that is unique to them. You avoid rebuilding accounting or email, and you still get a workflow that fits.
Typical hybrid builds:
- An integration that moves data automatically between your CRM, accounting and job systems.
- A customer portal on top of existing back-office tools, so clients can self-serve.
- A dashboard that pulls figures from several products into one view.
- An automation that handles a repetitive step, such as turning a web enquiry into a CRM record and a task.
Sometimes the layer grows until a full custom system makes sense. GRWW's own Ops Console is an example: it pulls website enquiries and Meta lead-ad leads into one pipeline automatically, alongside tasks, proposals, invoices and a client portal. Covering that workflow with separate products would mean several subscriptions and constant copying between them. For a CRM-specific version of this decision, see our comparison of custom CRM vs HubSpot, Zoho and Salesforce.
When is SaaS clearly the better choice?
Buy when the job is standard, the vendor is solid and your team will adapt happily. There is no prize for building what you can rent cheaply.
SaaS is almost always right for:
- Accounting, payroll and tax
- Email, calendars and document storage
- Video calls and team chat
- Standard e-commerce for a straightforward catalogue
- Early-stage businesses still finding their process
It is also right when you lack the time to manage a build. A custom project needs a decision-maker from your side; without one, even a good team will struggle.
What costs should you compare, honestly?
Compare five-year totals, not month one against a build quote. SaaS looks cheaper at the start and custom looks cheaper at scale, so the time horizon changes the answer.
On the SaaS side, include subscriptions at your expected headcount, paid add-ons, integration tools, and staff time spent on workarounds. On the custom side, include the build, hosting, maintenance at roughly 15–25% of the build cost per year, and your own team's time during the project.
For realistic build figures, see custom software costs in India and custom software development costs in Australia. If the numbers point towards building, our pillar guide to custom software development explains what happens next, from scoping to contracts.
Frequently asked questions
Is custom software always more expensive than SaaS?
Upfront, yes. Over several years it can be cheaper, especially when per-seat fees grow with headcount or when you replace several overlapping subscriptions. Compare five-year totals, including maintenance, before deciding.
Can I switch from SaaS to custom software later?
Yes, and many businesses do once their process has settled. The main work is data migration and retraining staff. Choosing SaaS products with good export options now makes that move easier later.
What if no SaaS product fits but I cannot afford a full custom build?
Look for the hybrid route. Keep the closest-fitting product and build an integration, portal or automation around its gaps. That often captures most of the benefit for a fraction of a full build.
How accurate is a scoring checklist?
It is a structured way to make your reasoning visible, not a precise model. Its real value is forcing an honest answer on each criterion, especially process stability and maintenance budget. Use it to decide whether a discovery phase is worth doing.
Who should fill in the checklist?
The person who owns the process, ideally with one or two people who do the work daily. Owners tend to underrate re-keying and workarounds; staff tend to know exactly where the time goes.
Next step
If your score lands in the middle or high range, the sensible move is a short discovery to test the idea before committing a full budget. Share your scores and the process you want to fix, and we will tell you honestly whether to build, buy or mix the two. You can also see what we build on our services page.