Build vs. Buy: Should You Develop Your Own Financial Calculation Engine in 2026?

Launching a Fintech or WealthTech is an exciting adventure. The ambition is to reinvent the user experience, create a seamless customer journey, and democratize investing. But beneath this polished interface lies a complex and costly technical reality: the quantitative calculation engine.

Quickly, every founder faces the most important strategic dilemma of their project: should they build this engine in-house or buy it via an API?

On paper, "building" is appealing. You imagine total control, proprietary technology. In reality, it's an iceberg where most founders only see the tip.

The Hidden Costs of "Build" (The Iceberg)

At Clearfolio, we've supported many players in this reflection. Here's what it really costs to develop a robust portfolio optimization engine:

1. Recruitment Costs (€150,000 / year)

The first obstacle is finding "the rare bird": a quantitative engineer (a "Quant") who is also an experienced Python developer. These profiles are rare, highly sought after, and their salary often exceeds €100,000 annually, not including recruitment and management costs.

2. Time Costs (12-18 months of R&D)

This isn't a project of a few weeks. You need to:

- Research, implement, and test models (Markowitz, Black-Litterman) - Handle edge cases and constraints (e.g., cardinality, transaction fees) - Set up data infrastructure Total: 12 to 18 months of R&D before having a stable product. Meanwhile, your competitors are already on the market.

3. Maintenance Costs (20-30% of dev time)

The engine is never "finished". You need to maintain it, fix bugs, adapt it to new market conditions, and evolve it. It's a permanent commitment that monopolizes precious resources that aren't allocated to your core product.

The Strategic Accelerator: "Buy"

Buying an API isn't a simple purchase, it's a strategic decision that frees up your two most precious resources: time and capital.

1. Time-to-Market (Launch in days)

Instead of 18 months, you can integrate complex optimization endpoints in a week. You can launch in a quarter, not in two years.

2. Focus on Your Core Business

The real value of your Fintech isn't the Markowitz algorithm. It's your user experience, your design, your customer acquisition, and your community. Outsourcing the quantitative "plumbing" allows you to focus 100% of your efforts where you're unique.

3. Instant Expertise

By integrating a specialized API, you instantly benefit from years of R&D. Your product, from day 1, can be more quantitatively performant than players established for 5 years.

Conclusion: Don't Build a Kitchen, Open a Restaurant

Building your own financial engine is like wanting to open a restaurant and starting by trying to forge your own pots. It's a costly distraction.

The real question isn't "Build vs. Buy", but "Do you want to be a quantitative R&D company or a Fintech that conquers a market?". Ready to accelerate?

Clearfolio Engine allows you to launch your product in days, not months. Discover how our API can propel your roadmap.