Mobile Banking App Modernization

Our collaboration involved migrating the platform to the cloud, providing access to a scalable and highly available database in a service-based model, with billing based on actual usage of computing resources.

August 26, 2026•

Project Scope

Our client is a mid-sized commercial bank operating in one of the Central and Eastern European markets. It serves retail customers, small and medium-sized enterprises, and corporations, with approximately half a million users relying on its services.

Client

A bank serving retail customers, SMEs, and corporations

Solution

Migration of the mobile banking platform to the cloud

Outcome

3 months were enough to successfully complete the cloud migration

Project Objective

Mobile Banking App Modernization

An additional benefit of the collaboration was immediate access to tools for building automated CI/CD processes. Because the client lacked in-house expertise in this area, it sought an experienced partner to support the bank’s team in migrating the platform and performing the necessary code optimization.

Our goal was to provide advisory support, coordinate the activities, and manage the migration process end-to-end. After evaluating available solutions, costs, and benefits, the bank selected Google Cloud as its cloud platform and began working with Ailleron, a certified Google Cloud Partner, to provide IT consulting, implementation support, and migrate the platform to the cloud.

Business Challenges

1. The Client’s Mobile Banking Channel

Mobile Banking as a Key Digital Customer Service Channel

Among the bank’s digital channels, mobile banking plays the most important role due to the rapidly growing number of active users, currently at around 300,000; a high login frequency of approximately 30 times per month, which is about three times higher than for online banking; and its critical role in mobile payments and securing payment card transactions through 3D Secure.

An Innovative Mobile App Tailored to Customer Needs

The bank’s mobile app is perceived by the market as an innovative solution. It supports both retail and business customers and enables a wide range of payment methods, including instant interbank transfers, e-commerce transactions, Apple Pay and Google Pay payments, 3D Secure authentication, and cardless ATM withdrawals.

Modern Architecture Built on Scalable Technologies

The mobile banking platform was designed and launched several years ago using a modern technology stack that includes native applications built in Kotlin and Swift, a microservices architecture, and an Oracle database. The environment is managed using OpenShift.

On-Premises Infrastructure Ready to Handle Periodic Spikes in Demand

The platform operates in an on-premises environment, with the hardware infrastructure providing sufficient performance and capacity to handle periodic spikes in demand – both regular peaks associated with payday periods and seasonal surges such as Black Friday, post-Christmas sales, and summer sales.

2. The Bank’s CTO Identified the Main Challenges Related to Maintaining the Mobile Platform

High Infrastructure Expansion Costs

The on-premises infrastructure must be ready to handle rapid user growth and several periodic demand peaks throughout the year.
Given the platform’s critical role in payment processing, the infrastructure must ensure high performance and reliability.
It's necessary to maintain reserve computing capacity that is used only a few times a year.

High Costs of Maintaining Resources Across Different Environments

With on-premises infrastructure, the bank must invest in maintaining multiple hardware environments.
Examples include development, staging, test, including User Acceptance Testing (UAT), pre-production, production, and reference environments used to compare results and verify potential errors.
Each environment includes hardware that must be maintained, periodically upgraded, and/or purchased to support new initiatives.

High Database Licensing Costs

A significant burden on the IT budget is the annual licensing fee for the database solution.
The bank is considering migrating to an alternative open-source database.

Project Implementation

The Journey to Google Cloud

As part of the preparations for migrating the mobile banking platform to the cloud, we carried out a series of optimization activities. We used Google Kubernetes Engine to replace the existing OpenShift solution, implemented the native Google Cloud SQL for PostgreSQL service to reduce database licensing costs, and planned the data migration to PostgreSQL.

Following the successful migration, the bank’s representatives expressed their willingness to continue the collaboration. They also entrusted us with monitoring the environment and helping optimize Google Cloud usage costs.

Scope of Collaboration

Cloud Migration Step by Step

Migration from OpenShift to Google Kubernetes Engine

Adaptation of the mobile banking back end to the Kubernetes environment
Integration with native Google Cloud services, such as Pub/Sub
First test deployment of the mobile banking platform on Kubernetes
Building and configuring a mature CI/CD pipeline
Setting up the required environments in Google Cloud: test, staging, and production
Test deployment of the mobile banking platform on GKE, including end-to-end (E2E) testing, performance testing, and sizing of the production environment
Configuration of secure inbound and outbound traffic and integration with external services outside the public cloud
Redirecting traffic from the local environment to Google Cloud

Configuring Cloud SQL for PostgreSQL

We have prepared and verified the Liquibase change sets
We launched the system on a test basis in a local environment using a PostgreSQL database
We have defined the sizing for Cloud SQL
We migrated data from Oracle to Cloud SQL for PostgreSQL in the test environment
We conducted performance tests and tuned the database
We have completed a test migration of the production database
We migrated the production database

Data Migration to Cloud SQL for PostgreSQL

We have configured Cloud SQL for the pre-production environment
We performed the data migration and then verified the migration results
We launched a trial version of our mobile banking service using the Cloud SQL database
We conducted performance tests and verified key performance indicators
We set up backup policies on a trial basis and ran restoration tests

Migration to the Production Environment

We have configured Cloud SQL for the production environment
We performed the data migration and then verified the migration results
We conducted performance tests and verified key performance indicators
We configured the backup policies and performed restore tests
We have migrated the system's traffic to the Cloud SQL database

Project Results

Smooth Migration to the Cloud

After receiving the green light from the CTO, we assembled a team together with the bank's experts and began implementing the previously agreed-upon plan.

Infrastructure Flexibility and Cost Reduction

The bank has gained full flexibility in utilizing its infrastructure capacity, while maintaining high availability and reducing the costs of maintaining multiple environments.

Modern Architecture on Google Cloud

Google Cloud is responsible for services related to the Cloud SQL database, the GKE Kubernetes cluster, asynchronous communication, and security patches.

Software Lifecycle Automation

Fully automated release management and CI/CD processes were implemented, which helped reduce the potential risk of human error and improve the quality of the software development process. The bank also eliminated database licensing costs from its IT budget.

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Mobile Banking App Modernization