Techresol and the Open Source Future of Fintech

Introduction

Fintech is moving faster than most industries can keep up with. Gone are the days of standing in line at a bank or waiting minutes for a clunky app to load. Customers now expect instant payments, mobile-first experiences, and AI-driven insights. Meanwhile, the software running behind the scenes at most financial companies is ancient. According to IBM, more than 40% of online banking systems, 80% of in-person credit card transactions, and 95% of ATM transactions still run on mainframes and decades-old code. And keeping these legacy systems alive is getting painfully expensive. IDC Financial Insights projects global spending on outdated banking tech to climb from $36.7 billion in 2022 to $57.1 billion by 2028, with maintenance costs growing nearly 8% a year.

So what's the way out? Open source. It has quietly become the foundation of modern finance, and companies like Techresol are among the first to build their fintech offerings on it from day one. This post breaks down why the shift matters, where legacy systems fall short, and what open source brings to modern finance.

The High Cost of Legacy Software

For decades, banks bought expensive software from a handful of vendors, signed long-term contracts, and hoped those vendors would keep pace with change. That model is breaking down, and the numbers are brutal.

Maintenance is eating everything. Deloitte research shows U.S. bank IT departments spend over 55% of their tech budgets just keeping the lights on, with only 19% left for innovation. Some estimates put maintenance as high as 75%. Vendor lock-in quietly drains the rest. Data ends up in closed formats, APIs are limited, and contracts renew at ever-higher prices — what analysts call a "hidden tax" on innovation.

And when something goes wrong, it goes really wrong. The 2018 TSB migration disaster locked millions of UK customers out of online banking for weeks, triggering a £48 million fine and over £400 million in losses. Meanwhile, 95% of banking executives now identify legacy cores as barriers to customer-centric growth, and Accenture says modernisation can cut total cost of ownership by 38–52%.

What Open Source Brings to Fintech

Open source is no longer a niche movement — it's the foundation that modern software is built on. According to the 2025 State of Open Source Report, 96% of organizations either increased or maintained their use of open source software in the past year, and 26% significantly ramped it up, with cost efficiency cited as the top driver.

Financial services is right at the centre of this shift. The FINOS and Linux Foundation 2025 report found that nearly one-fifth of financial firms now save more than $1 million a year from open source use. But the wins go well beyond cost. In financial services, the top reported benefits are industry standards and interoperability (59%), reduced product development costs (54%), and innovation (53%). The tech stack fintech is moving toward — AI/ML, cloud and containers, CI/CD pipelines — is overwhelmingly open source.

Add transparency that regulators can audit, flexibility without lock-in, and security strengthened by thousands of eyes on the code, and the picture is clear. The global open banking market reflects the momentum too, projected to triple from $30.89 billion in 2024 to $94.14 billion by 2029, powered almost entirely by APIs and open standards.

Why Everyone in Fintech is Betting on Open Source

A fair question: if open source is so great, why were banks so slow to adopt it? The honest answer is perception. Leaders worried open code was messier and less auditable than vendor software. Regulators have flipped that thinking. Europe's Digital Operational Resilience Act (DORA), which entered mandatory enforcement across the EU on January 17, 2025, rewards exactly what open source does well: transparency, traceability, vulnerability management, and full visibility into every software component. Ironically, DORA now classifies unsupported, unpatchable systems as "Legacy ICT" — meaning that "safe" closed platform you can't update is now the compliance liability.

The momentum is unmistakable. FINOS, the Fintech Open Source Foundation allied with the Linux Foundation, surpassed 100 members in January 2025, with Citi, Goldman Sachs, JPMorgan Chase, Morgan Stanley, BlackRock, Capital One, and the three major hyperscalers all onboard. Goldman Sachs open-sourced its Legend data platform. JPMorgan contributed Perspective and Quorum. Morgan Stanley released ComposeUI and Morphir. Deutsche Bank shared Plexus Interop and Waltz. As Morgan Stanley's Dov Katz put it: banks now collaborate openly on everything outside their core competitive advantage.

Techresol: Embracing Open Source From Day One

That shared foundation is where Techresol plants its flag. While most traditional finance vendors spent the last decade perfecting proprietary lock-in, Techresol made a different bet early on — build on open, transparent, community-backed technology, and pass every benefit straight to financial clients.

Open, modular architecture. Instead of forcing clients into monolithic platforms, Techresol builds on cloud-native, microservices-based frameworks — the same foundations FINOS members have standardised around. Clients can swap, extend, or upgrade individual components without the "rip-and-replace" pain that has haunted core banking modernisation for years.

Interoperability by default. Every solution is designed to plug into the wider fintech ecosystem — payment rails, open banking APIs, KYC and AML providers, regulatory reporting tools — instead of holding customer data hostage in proprietary formats.

Transparent, audit-ready delivery. Because the underlying stack is open, clients and their regulators get full visibility into what the code does and how it runs. That's a direct answer to what DORA, PCI-DSS, and SOC 2 auditors are actually asking for.

Cost structures that work for clients, not vendors. Without locked-in per-user licensing or forced annual price hikes, clients keep more of their IT budget free for real innovation — a big reason nearly one in five financial firms using open source now report over $1 million in annual savings.

Making the Shift: A Practical Path Forward

Moving to open source isn't a flip of a switch — it's a staged journey, and the institutions doing it well follow roughly the same playbook. Start by auditing what you already have. Most financial firms are surprised to learn they're already running open source in CI/CD pipelines, Linux servers, and data platforms — and under DORA, a full Software Bill of Materials is now a baseline requirement. From there, target the high-cost, low-flexibility pieces first: the vendor contracts growing fastest, the modules that refuse to integrate, the systems quietly delaying product launches. Ship value in 90-day increments alongside existing systems rather than betting everything on a single migration. Invest in governance through an Open Source Program Office, as every major FINOS member bank now does. And choose partners who build open by default, not as an afterthought.

That's where Techresol fits in. Open source has stopped being a gamble in financial services — it's the path the biggest banks, the strictest regulators, and the fastest-growing fintechs are all walking together. Staying on yesterday's proprietary stack isn't "safe" anymore, it's the expensive, slow, compliance-heavy option. The financial companies that win the next decade will be the ones that make the shift early and with the right partners. Techresol was built for exactly this moment — open by design, fluent in modern fintech stacks, and focused on helping financial institutions escape the legacy trap without the pain.

Ready to see what an open-source-first fintech stack looks like for your business? Reach out to Techresol and let's map your roadmap together.