The verdict in three sentences
Refactoring a legacy SaaS that is too slow and too costly to maintain runs in Toronto at 55,000 to 165,000 CAD over 4 to 8 months, after a technical audit at 4,000 - 11,000 CAD. The right method is the progressive rewrite (strangler fig): you replace modules one by one without pausing production, which cuts infra costs by 20 to 40 % and lowers risk at every step. The big-bang rewrite (throw everything out, recode it all) is the classic trap: it often doubles the budget and freezes new features for months.
Audit first, refactor second
You don't refactor blind. The audit quantifies technical debt and prioritizes. 2026 ranges.
| Service | Scope | Cost | Timeline |
|---|---|---|---|
| Technical audit | Code, arch, security, infra cost | 4,000 - 11,000 CAD | 1 - 2 wk |
| Targeted refactor | 1 to 2 critical modules | 21,000 - 55,000 CAD | 6 - 12 wk |
| Progressive rewrite | Strangler fig, 4 to 6 modules | 55,000 - 125,000 CAD | 4 - 7 mo |
| Full rebuild | New codebase + migration | 110,000 - 165,000 CAD | 6 - 8 mo |
| Data migration | Scripts, tests, cutover | 8,000 - 25,000 CAD | 3 - 6 wk |
The audit pays for itself: it avoids refactoring modules that work and focuses the budget where debt truly costs (slowness, bugs, cloud bills).
Strangler fig versus big-bang
Two strategies, two risk profiles. The table quantifies the 2026 gap.
| Criterion | Strangler fig (progressive) | Big-bang (rewrite) |
|---|---|---|
| Typical budget | 55,000 - 125,000 CAD | 110,000 - 165,000+ CAD |
| Duration | 4 - 7 mo | 6 - 12 mo |
| Production meanwhile | Continuous | Often frozen |
| Overrun risk | Low to medium | High |
| New features | Possible in parallel | Suspended |
| Infra cost reduction | 20 - 40 % progressive | 20 - 40 % at the end |
Strangler fig almost always wins for a SaaS in production with paying customers: each refactored module delivers a measurable gain (speed, cost, stability) without pausing the business.
Need a professional website?
Kolonell builds websites that attract clients, optimized for the Sénégalese market. Free quote in 2 minutes.
Mini case study
Julien, CTO of a SaaS vendor in Toronto, faces a cloud bill of 5,800 CAD/month and degraded response times churning his customers. Audit at 8,000 CAD: debt is concentrated in two modules (search + reporting). Progressive refactor of those two modules: 66,000 CAD over 4 months. Result: infra bill down to 3,700 CAD/month (-36 %, i.e. 25,200 CAD/year saved) and reduced churn. The refactor pays back in 31 months on infra alone, not counting regained customer retention.
FAQ
When to refactor rather than patch? When maintenance exceeds 30 % of the team's time or when the infra bill climbs unrelated to traffic. Below that, an audit at 4,000 - 11,000 CAD will tell you whether targeted fixes suffice.
How much do you save on infra? A well-run refactor cuts cloud costs by 20 to 40 %: caching, optimized queries, right-sizing. On a 5,800 CAD/month bill, that is 1,160 to 2,320 CAD/month recovered.
Is a big-bang rewrite always to avoid? No, but rarely justified: it makes sense if the codebase is unrecoverable (dead tech, no docs). Otherwise it costs 110,000 - 165,000+ CAD and freezes features for 6 to 12 months, a major business risk.
Can you refactor without pausing production? Yes, that is the whole point of strangler fig: you progressively route traffic to the new modules. Zero downtime, measurable gains at each step.
How much does data migration cost? Budget 8,000 to 25,000 CAD depending on volume and schema complexity. Never underestimate it: a failed cutover costs more than the refactor itself.
Let's scope your project. Send us your infra bill, your team size and your two most painful modules; we start with a 4,000-11,000 CAD audit then scope a progressive refactor between 55,000 and 165,000 CAD. 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.
