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Core Banking: Build or Buy? A Decision Guide for LATAM
- WAU Marketing
- Jan 6
- 4 min read
Updated: Jun 23
The question isn't "build or buy." It's where you want to spend your best engineering hours.
Nearly every financial institution in the region reaches this fork sooner or later. The core that carried it for fifteen years starts to drag: every new product takes months, every fintech integration becomes a project, and IT spends more time maintaining the old than building the new. That's when the classic question shows up: do we build our own core or buy one?
It's the right question, asked the wrong way. Framing it as a yes or no—all in-house or all outsourced—almost always leads to the most expensive answer. Let us offer a different lens.
What building costs (and why almost no one should)
Building a core banking system from scratch is one of the hardest software projects there is. It isn't an app. It's the bank's ledger: it has to balance to the cent, run 24/7, and survive an audit. And the industry numbers are blunt: an in-house core takes three to five years and routinely tops $50 million, while a modern vendor platform reaches production in 18 to 36 months, according to Crassula's core banking guide.
There's a cost almost no one puts on the spreadsheet: opportunity cost. Every engineer you assign to building an accounts engine is an engineer who isn't building what sets you apart from the bank next door. In LATAM that hits harder, because senior talent in financial systems is scarce, expensive, and fought over by the fintechs themselves.
When does building actually make sense? When the core is your differentiator, not your infrastructure. If you're a tier-one institution with unusual requirements and a team of more than fifty dedicated engineers, the math changes, as Crassula also frames it. For the other 95% of the region, building the full core means solving a problem that's already solved.
What buying costs (and the demo trap)
Buying sounds simpler, and often it is: deployment in weeks, a subscription model instead of a capital project, maintenance handled by the vendor. But there's a trap, and it's the one that derails the most budgets.
The license price is just the tip. In practice, the subscription is only a fraction of total cost of ownership; the rest goes to implementation, data migration, training, integrations and—crucial in this region—the regulatory compliance layer that often isn't included. In fact, a useful industry rule of thumb says that for every dollar you spend on vendor software, count on two or three in implementation and another per year in operation, according to Crassula. The real economic weight isn't in the license—it's in integration, data migration, and process reengineering, as Rootstack underscores. A core that costs $100K a year but demands $500K in integration and localization can end up pricier than one at $200K that's ready to operate.
Here's the detail that separates a good purchase from a bad one: most cloud-native cores on the market were designed for Europe or Asia. The local regulatory layer—CNBV and Banxico in Mexico, AML rules, each regulator's reporting—rarely comes out of the box. Either your team builds it, or an integrator does, or you fall short in front of the regulator. "We adapt to local regulation" can mean three very different things; you need to know which before you sign.
The factors that actually decide it
When we walk an institution through this decision, we boil it down to five concrete questions:
Time-to-revenue. In financial services, every month you take to launch is a month without revenue from that product. The institutions that choose well optimize for time-to-revenue, not for the flashiest feature in the demo.
Five-year TCO. Not the sticker price: the cost of maintaining, integrating, scaling and complying, summed over time. Rule of thumb for a mid-size bank: for every dollar in vendor software, count on two or three in implementation and another per year in operation.
Talent. Do you have—and can you keep—the team to build and maintain a core to the standards a financial system demands? If the honest answer is "not really," half the decision is already made.
Migration risk. It's the barrier that stalls modernization most: the fear of disrupting operations keeps many institutions trapped in tech that no longer serves them. A good vendor lowers that risk with a phased, wave-by-wave migration; a bad one hands it to you whole.
Control and regulation. The more particular your operation and the faster your regulatory framework changes, the more it's worth being able to extend the platform without asking permission.
The real answer is rarely binary
The strategy that works best isn't build everything or buy everything: it's buy the foundation and build your differentiator. You buy the core—ledger, accounts engine, processing—where reinventing the wheel earns you nothing, and you reserve your best engineers for what makes you distinct: the customer experience, the credit product no one else offers, the integration with your ecosystem. It's what the region's most successful neobanks do: they run on a modern core from day one and put their energy where they actually compete.
And something we always repeat: this isn't a once-and-done decision. Revisit it every 12 to 18 months, because what you buy today can become part of your core tomorrow—and vice versa. Technology, owned or acquired, is a means. The edge comes from how you integrate it and put it to work for your value proposition. It helps to keep the backdrop in mind: up to 60% of the region's core banking systems still run on legacy technology, per Finnovista figures cited by Galileo—the decision to modernize isn't marginal, it's the majority case.
How we see it at WAU
At WAU we work with financial institutions across the region that are at exactly this fork. We don't believe in the off-the-shelf answer—neither "build it all" out of technical pride, nor "buy it all" under commercial pressure. We believe in looking at your operation, your regulatory framework and your team, and designing the path that gets you to your goals faster and more sustainably.
If your core is already holding you back and you want to put real numbers on the decision—build, buy or blend—let's talk. We'll help you build the case with timelines, TCO and risk that are real for your institution, not for a demo. 👉 Book a conversation with our team.
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