The verdict in three sentences
Buy a SaaS as long as your need is standard and the tool does not carry your differentiation. Build custom once three or more criteria align: core process, high user volume, expensive licences, blocking API limits, competitive edge or unacceptable vendor dependence. The decision is made with a weighted grid, not on instinct.
The 6 decision criteria, weighted
Each criterion gets a weight by strategic impact. You rate your situation 0 to 5; a high weighted score leans toward custom.
| Criterion | Weight | Leans to build if... |
|---|---|---|
| Core business process | 25 % | the tool carries your competitive edge |
| Number of users | 15 % | > 50 active seats |
| Annual licence cost | 20 % | > USD 60,000 / year |
| API / integration limits | 15 % | the SaaS caps your connections |
| Need for differentiation | 15 % | competitors run the same SaaS |
| Vendor risk / dependence | 10 % | price hike or acquisition likely |
A weighted score above 60 % justifies seriously studying a targeted build.
The threshold calculation in figures
Take a SaaS at USD 48,000/year (60 seats at USD 67/month). A custom MVP quoted between USD 70,000 and 150,000, plus USD 1,500/month maintenance, compares as follows:
| Scenario | Year 1 | Year 3 | Year 5 |
|---|---|---|---|
| SaaS (USD 48,000/yr) | USD 48,000 | USD 144,000 | USD 240,000 |
| Build MVP 70,000 | USD 88,000 | USD 124,000 | USD 160,000 |
| Full build 150,000 | USD 168,000 | USD 204,000 | USD 240,000 |
With a USD 70,000 MVP, custom becomes cheaper from year 2. With a full USD 150,000 scope, break-even lands around year 5: that is why a targeted MVP is recommended before a full build.
Mini case study
Karim, managing director of a logistics firm in Dubai, runs a fleet-tracking SaaS at USD 67/user/month for 60 drivers and dispatchers, or USD 48,240/year. The SaaS refuses to expose the real-time API he needs for his customer portal; a custom connector is quoted at USD 12,000. Weighted grid score: 68 % (core process + API limits + differentiation). A custom MVP covering tracking and the portal is quoted at USD 95,000 + USD 1,500/month. Over 3 years: USD 149,000 versus USD 144,720 of SaaS — near break-even, but with an open API and a decisive customer advantage. He launches the build.
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FAQ
Which criterion matters most?
Whether the process is "core business", weighted at 25 %. If the tool carries your differentiation, custom is justified even at moderate volume, because a standardised SaaS makes you identical to competitors.
Must everything be built at once?
No. Start with an MVP targeted on the most strategic function (USD 70,000 to 150,000). You validate value before investing in the full scope, and ROI arrives sooner.
What if the SaaS covers 80 % of my need?
Keep the SaaS and build only the missing 20 % as a complement, via its API if it allows. Full custom is only justified if API limits block your business.
How long for an MVP?
Expect 8 to 16 weeks depending on scope. A well-framed MVP ships the core function quickly, then grows through quarterly iterations.
How do I quantify vendor risk?
Estimate the impact of a 10 % yearly hike and a possible acquisition forcing migration. Over 5 years, this risk often represents 20 to 30 % of total SaaS cost, to factor into the decision.
Let's scope your project. Send us your 6 rated criteria and your SaaS bill: we compute your weighted score and quote a targeted MVP. Detailed quote within 48 h. WhatsApp +221 77 596 93 33.
Mohamed Bah
Fondateur, Kolonell
Passionate about digital and entrepreneurship in Africa, Mohamed has been helping Sénégalese businesses with their digital transformation since 2020. Founder of Kolonell, he believes every SME deserves a professional and accessible online présence.
