Custom vs SaaS: How to Choose?

It’s one of the most common questions we receive at INYSTER: “Should we use an existing software solution or build something custom?”

The honest answer: it depends. But here’s a framework to help you make the right choice.

SaaS: the quick solution

SaaS (Software as a Service) is a cloud-hosted application, accessible via a monthly subscription. Salesforce, HubSpot, Monday, Notion — you’re probably already using several of them.

Advantages of SaaS

• Immediate start: create an account and start using it the same day
• Low entry cost: a few dozen euros per month to get started
• Maintenance included: updates, security, hosting — everything is handled by the vendor
• Community and support: documentation, forums, tutorials

Limitations of SaaS

• Functional rigidity: you have to adapt your process to the tool, not the other way around
• Cumulative costs: 50 EUR/month x 10 users x 12 months = 6,000 EUR/year — and it keeps increasing
• Dependency: your data is held by a third party, and the vendor can change their pricing or terms at any time
• Limited customization: the available “customizations” often have frustrating limitations

Custom development: the solution tailored to you

A custom tool is developed specifically for your company, your processes, and your constraints.

Advantages of custom development

• Perfect fit: the tool does exactly what you need, nothing more, nothing less
• Scalability: you can add features as you go
• Ownership: the code belongs to you, your data stays with you
• Competitive advantage: a unique tool that your competitors don’t have

Limitations of custom development

• Initial investment: the development cost is higher than a first SaaS subscription
• Lead time: it takes time to design and develop
• Maintenance: you need to plan for an ongoing maintenance budget

The real calculation: total cost over 3 years

This is where the comparison gets interesting. Let’s take a concrete example.

Scenario: order management tool for an SME with 15 employees

SaaS option:

• Subscription: 80 EUR/month x 15 users = 1,200 EUR/month
• Training: 2,000 EUR (one-time)
• Customization: 3,000 EUR (integrator)
• Total cost over 3 years: 48,200 EUR

Custom option:

• Initial development (MVP): 12,000 EUR
• Year 1 enhancements: 5,000 EUR
• Maintenance years 2-3: 500 EUR/month = 12,000 EUR
• Total cost over 3 years: 29,000 EUR

In this scenario, custom development is 40% less expensive over 3 years — and the tool matches the exact needs.

This isn’t always the case, of course. For a general-purpose CRM with 2 users, a SaaS at 30 EUR/month will always be more relevant.

The decision grid

Choose SaaS if:

• Your need is standard (basic CRM, emailing, simple project management)
• You have fewer than 5 users
• You don’t have industry-specific business processes
• Your initial budget is very tight (< 5,000 EUR)

Choose custom development if:

• Your business process is specific to your industry
• You’ve been working around SaaS limitations with Excel exports or duplicate data entry
• You have more than 10 users
• Data control matters (GDPR, sensitive data)
• You’re looking for a competitive advantage

Choose a hybrid approach if:

• You want to keep your existing SaaS tools but connect them together
• You need a dashboard that aggregates data from multiple sources
• Some processes are standard (SaaS) while others are highly specific (custom)

The INYSTER approach

We’re not dogmatic. Sometimes, the best recommendation is “use this SaaS.” We’d rather give you honest advice than develop a tool you don’t actually need.

When custom development is the right call, we start with an MVP to validate the approach before building the full solution. It’s the best way to control the budget while confirming the tool’s value.

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Torn between SaaS and custom? Take 30 minutes to discuss it with us — we’ll give you an honest opinion, even if the answer is “keep your SaaS.”