The fundamental difference
A SaaS product offers a ready-built solution, used by many customers, with limited customization. Custom software is built specifically for that process, with the cost and time that dedicated development entails. Neither is universally “better” — it depends on how specific the process is.
When a SaaS is the right choice
When the process is similar enough to that of other companies in the field that a generic product covers the need without constant compromises. The cost is lower and it’s faster to get started — there’s no need to reinvent something that already exists and is well built.
When custom software is the right choice
When processes are specific enough that a SaaS would force constant workarounds, or when full control over data and integrations is needed — for example, confidentiality requirements that don’t fit a multi-tenant product.
Costs and trade-offs
SaaS: predictable cost, fast start, but limited customization and dependence on the vendor’s decisions. Custom software: higher upfront cost, longer delivery time, but full control and an exact fit to the process.
Examples
Our own products illustrate both directions: eSRL and 1002 are designed as SaaS products, for a broad audience with similar needs. For clients with highly specific processes, we recommend custom software — also see the page on building your own SaaS product for cases where the intent is to build a product, not just use an existing one.
Resources and references
- Gartner — Comparison of Total Cost of Ownership Between On-Premises and SaaS Business Applications — the real cost of a SaaS subscription includes integration, data migration, training, and customizations, often overlooked in the initial comparison with a dedicated, purpose-built system.
- A simple vendor-independent calculation to compare: long-term SaaS cost = annual subscription × years of use + integration/migration costs; custom software cost = initial development + annual maintenance. The break-even point varies case by case, but it’s worth calculating before deciding, not assuming.
Checklist
- Is the process similar to that of most companies in the field, or does it have real particularities?
- Does an existing SaaS cover 80%+ of the need without constant workarounds?
- Are specific integrations required that the SaaS doesn't support natively?
- Is control over data a critical requirement (regulations, confidentiality)?
- Do the available budget and time support dedicated development?
Risks to consider
- Custom software built without a real need for customization becomes a cost without proportional benefit.
- A SaaS forced onto too specific a process leads to constant workarounds that, cumulatively, cost more than dedicated development.
- Migrating later from a SaaS to an in-house system can be costly if the data is difficult to export.