Should you rebuild your existing app or start fresh? Learn the decision framework, cost analysis, and ROI calculations for both approaches.
Rebuild vs. New Build: Decision Framework
When to Rebuild
Rebuild if: Existing app has valuable features and data, data migration is feasible, timeline is critical (60-90 days vs. 120+ days), cost is a concern (rebuilds cost 60-80% of new builds), or you want to preserve user data and workflows.
When to Build New
Build new if: Architecture is fundamentally broken, security risks are severe and can't be patched, tech stack is obsolete and migration is complex, or you're pivoting to a completely different product.
Cost Comparison
Rebuild Costs: Foundation tier $50K (60 days), Growth tier $85K (90 days), Scale tier $125K (120 days). Typically 60-80% of new build cost.
New Build Costs: Foundation tier $60K (90 days), Growth tier $100K (120 days), Scale tier $150K (150 days). Typically 20-40% more expensive than rebuilds.
Why Rebuilds Cost Less: Existing features can be preserved, data migration is simpler, architecture patterns are established, and timeline is shorter.
Timeline Comparison
Rebuild Timeline: Foundation 60 days, Growth 90 days, Scale 120 days. Faster because features exist and architecture is understood.
New Build Timeline: Foundation 90 days, Growth 120 days, Scale 150 days. Longer because everything is built from scratch.
Risk Analysis
Rebuild Risks: Legacy code issues may persist, data migration challenges, technical debt may remain if not addressed properly.
New Build Risks: Longer timeline, higher cost, loss of existing features, data migration from old system, user disruption.
ROI Comparison
Rebuild ROI: Lower initial cost, faster delivery, preserves existing value, average 1,733% 5-year ROI.
New Build ROI: Higher initial cost, longer timeline, but clean slate with no legacy issues.
Recommendation
Choose rebuild if: Existing app has value, timeline is critical, or budget is constrained. Choose new build if: Architecture is fundamentally broken or you're pivoting completely.