Category: Software Engineering
Custom software pays off financially when the accumulated gains from productivity, differentiation, and cost reduction exceed the initial investment and ongoing maintenance costs within an acceptable timeframe. In general, this happens when the process is strategic, serves many users, requires relevant integrations, or generates high recurring SaaS costs.
The decision should not be based solely on the initial price
An off-the-shelf SaaS solution almost always costs less to get started. The company pays for implementation, subscription fees, and possibly consulting, enabling it to launch a relatively standardized operation within days or weeks.
Custom software concentrates more costs upfront: discovery, architecture, development, testing, infrastructure, security, and change management. Therefore, comparing only the first invoice artificially favors SaaS.
The correct analysis considers the total cost of ownership, or TCO, over a three- to five-year horizon. It should also account for the financial benefits each alternative can generate.
The comparison can be summarized as follows:
Financial result = accumulated benefits − accumulated TCO
Benefits may include:
- work hours eliminated through automation;
- reduction in errors, rework, and losses;
- increased capacity without new hires;
- revenue or conversion growth;
- reduction in subscriptions and redundant systems;
- shorter service or processing times;
- creation of a feature that differentiates the company.
If these gains cannot be measured, development risks becoming a technology project without economic justification.
How to calculate the real cost of SaaS
The subscription price advertised by the vendor is only part of the TCO. To calculate the annual cost of SaaS, consider:
- subscription fees per user, unit, volume, or transaction;
- required additional modules;
- implementation, configuration, and training;
- integrations charged separately;
- consulting services for process adaptation;
- excess storage, traffic, or usage;
- contractual price adjustments and exchange-rate fluctuations;
- the cost of exporting, processing, or migrating data;
- manual work maintained because of product limitations;
- the cost of downtime or vendor dependency.
A simplified formula is:
SaaS TCO = implementation + subscriptions + integrations + internal operations + limitations + exit migration
The “limitations” item deserves attention. If ten professionals spend four hours per week working around a system restriction, that represents 160 monthly work hours not reflected in the subscription fee. Multiplying those hours by each professional’s fully loaded cost turns the inefficiency into a comparable monetary value.
The commercial model also changes the calculation. Per-user pricing may work well for small teams but grow disproportionately in operations with hundreds of people. Transaction-based pricing, on the other hand, may penalize the very increase in volume the company is seeking.
How to calculate the cost of custom software
The TCO of proprietary software includes more than the development of its first version:
Custom software TCO = discovery + development + infrastructure + maintenance + evolution + governance
Discovery defines processes, requirements, risks, and metrics. Development includes the interface, backend, integrations, testing, and deployment. After launch, there are ongoing costs related to monitoring, bug fixes, security, backups, updates, and functional evolution.
A recurring mistake is treating the budget for the initial version as the final cost. Living systems need to keep up with changes in the business, browsers, operating systems, APIs, security rules, and external integrations.
There is also an opportunity cost. During development, the organization has not yet captured all the expected benefits. For this reason, incremental deliveries are often financially superior to long projects with a single final deployment.
The company should also contractually clarify:
- who owns the source code and data;
- how documentation and knowledge transfer will work;
- which environments, repositories, and access credentials will remain under its control;
- which service levels will be adopted;
- how vulnerabilities and incidents will be handled;
- how much it will cost to maintain and evolve the system.
Break-even point example
Consider a hypothetical scenario with 180 users. A SaaS solution costs R$180 per user per month, plus R$8,000 per month in integrations and operational services. The total monthly cost is R$40,400, excluding implementation and price adjustments.
A custom solution requires an initial investment of R$480,000 and R$22,000 per month for infrastructure, support, and evolution. The simplified break-even point would be:
Payback = initial investment ÷ monthly savings
Payback = R$480,000 ÷ (R$40,400 − R$22,000) = approximately 26 months
Over three years, without considering cost of capital, taxes, or price adjustments:
- SaaS: R$40,400 × 36 = R$1.454 million;
- custom software: R$480,000 + (R$22,000 × 36) = R$1.272 million;
- estimated difference: R$182,400 in favor of custom software.
This example does not prove that development is always the better option. It shows how user volume, recurring pricing, and the analysis horizon can reverse a comparison that seemed favorable to SaaS in the first month.
For a more rigorous decision, apply net present value to the cash flows and test at least three scenarios: conservative, likely, and optimistic. The conservative scenario should include delays, scope increases, and lower-than-expected benefits.
When building from scratch tends to pay off
Custom software becomes financially stronger when several of the criteria below are present:
- the process is central to revenue, margins, operations, or customer experience;
- off-the-shelf tools require many manual workarounds;
- SaaS costs grow rapidly with users or transactions;
- deep integrations with ERP, CRM, devices, or legacy systems are required;
- proprietary rules generate a competitive advantage;
- the company needs to control data, infrastructure, or audit trails;
- the operation has enough scale to spread out the investment;
- the system will be used for at least three to five years;
- automation eliminates a measurable amount of work;
- there is a team and budget to maintain the product after launch.
It is not necessary to build absolutely everything. An economically efficient architecture can combine off-the-shelf components for authentication, payments, messaging, or infrastructure with proprietary modules for strategic rules.
When SaaS is the more rational choice
SaaS is usually superior when the process is common across the market and does not represent differentiation. Corporate email, video conferencing, and many administrative functions rarely justify being rebuilt in their entirety.
Choose an off-the-shelf solution when:
- the need is urgent and well served by the existing product;
- there are few users or a low transaction volume;
- the process is still changing rapidly and has not been validated;
- the initial budget is limited;
- the requirements are mostly standardized;
- there is no internal capacity to govern a digital product;
- switching vendors is feasible and the data can be exported;
- the development risk exceeds the potential savings.
Purchasing SaaS can also serve as a learning stage. The company validates the workflow, identifies actual limitations, and only then develops the modules that justify ownership.
Trade-offs that do not appear in the spreadsheet
The financial decision depends on technical and operational factors. A proprietary system offers greater control but transfers responsibility for availability, security, and evolution to the company. SaaS reduces this burden but creates dependency on the vendor’s roadmap, commercial policies, and continued operation.
Pay particular attention to:
Dependency and portability
Check whether data, attachments, histories, and configurations can be exported in usable formats. Having an API does not, by itself, mean that migration will be simple.
Security and compliance
Proprietary software is not automatically more secure. It enables specific controls but requires ongoing management of access, dependencies, vulnerabilities, logs, backups, and incidents. With SaaS, the company must review the contract, architecture, data segregation, and shared responsibilities.
Speed and fit
SaaS delivers ready-made features quickly, but it may force the business to adapt its processes. Custom software follows the operation, but its value depends on the quality of discovery, architecture, and delivery.
Financial decision checklist
Before approving the investment, answer the following questions:
- What is the TCO of each alternative over 36 and 60 months?
- How many monthly hours will actually be saved?
- What is the fully loaded cost of those hours?
- Is there a verifiable impact on revenue, margins, or risk?
- How many months will it take to achieve payback?
- Does the calculation include maintenance and evolution?
- What happens if the project is delayed by 30%?
- What happens if only 50% of the benefits are achieved?
- Is there an MVP capable of validating the riskiest assumptions?
- Will code, data, documentation, and infrastructure be portable?
- Who will be responsible for the product after deployment?
A robust decision should remain defensible under the conservative scenario. If the return only appears with perfect adoption, no delays, and maximum gains, the justification is fragile.
How Predictor Solutions addresses this
Predictor Solutions begins by modeling the problem economically and technically instead of assuming that every process requires development from scratch. The work may involve discovery, TCO calculation, MVP prioritization, architecture, development, applied artificial intelligence, data engineering, cloud/DevOps, security, and integrations such as HL7 v2 and FHIR.
When a combined approach is more efficient, SaaS components are integrated with proprietary modules. When control, scale, or differentiation justify ownership, the solution is built through incremental deliveries, metrics, and validation criteria.
Across its projects and product portfolio, Predictor Solutions has served 9 medium-sized and large companies. The reported aggregate results include average savings of R$1.32 million per client per year, an average productivity increase of 70%, and 43% profit growth in six months—indicators that should be interpreted within the context and metrics of each operation, not as an automatic guarantee for new projects.
To evaluate SaaS versus custom software based on cost, risk, and return: contato@predictorsolutions.com / WhatsApp +55 31 98835-3246.