Lithuanian electronic money institution ConnectPay has turned the proprietary core banking stack it built for its own operations into a standalone commercial product. The platform, now branded Serdis, is being offered to other European EMIs and financial institutions that want cloud-native infrastructure they can run and eventually own.
Serdis began life internally as a project called Mars.
ConnectPay developed it to end reliance on an external core provider—the layer that records balances, posts transactions, and sits at the center of regulatory reporting.
In July 2025 the company switched its live books onto the new system.
The cutover moved the equivalent of €14 billion in annual transaction volume over a single weekend and produced no customer-visible outage.
Before that weekend, the team had run the new core in parallel with the old vendor for nine months so reconciliation issues could be fixed in advance rather than during go-live.
ConnectPay now argues that experience is the product’s main differentiator.
Most core engines, the company says, are written by software vendors that have never held safeguarded client funds or answered a central bank supervisor.
Serdis was designed inside a licensed EMI and is therefore shaped by the same compliance calendar ConnectPay itself must meet.
Updates the firm builds for its own license can be passed through to licensees.
Founder and CEO Marius Galdikas put it bluntly: the platform “was built to run, not sell.”
Technically, Serdis is an AWS-native system running on a distributed microservices architecture on Amazon EKS.
It includes a tree-structured general ledger, real-time balances, automated IBAN lifecycle management, and dedicated FX and treasury engines.
Payment rails are native: SEPA, SEPA Instant, and SWIFT MT/MX. White-label web and mobile banking front ends ship pre-integrated.
Deployment is inside the client’s own AWS account, and contracts include a source-code buyout option so institutions can take full ownership rather than remain perpetual tenants.
The commercial pitch lands against a backdrop of tightening operational-resilience rules.
Industry figures cited by ConnectPay suggest roughly 70 percent of large banks still sit on legacy cores, a concentration that DORA and similar regimes treat as third-party risk.
Galdikas, who also chairs the Lithuanian Fintech Association, has framed the launch as a step toward a European market in which institutions own their books instead of renting them.
Coverage of the announcement has described the move as a sign that successful EMIs are no longer content to act only as distributors of someone else’s technology.
The name itself is a nod to origin: “Serdis” comes from the Lithuanian word šerdis, meaning core. For firms evaluating a migration, ConnectPay points to its own proof point—the parallel-run period and the quiet weekend cutover—as evidence that a regulated institution can reclaim technical control without interrupting customers.
