Introduction
When you’re creating a fintech application, the decision of what technology stack to use should not just be made from a technical perspective; it can also be looked at as a strategic decision. The technology stack that you choose will have an overall effect on matters such as regulatory compliance, the performance of your application, your ability to grow quickly or make changes to your product often, and whether or not your end-users (and auditors) are satisfied.
At Appricotsoft, we assist fintech entrepreneurs and product managers as they work through the challenges of balancing compliance, performance and product velocity. Whether you are creating your first neobank, expanding your payment gateway or developing tools for PSD2, KYC, or open banking, etc., the technology you select will either aid or impede your business. Here are a few tips on how to make those decisions.
Understanding the Bigger Picture: Fintech Applications Have Unique Technology Stacks
The technology stacks used by fintech applications are unique in that, when compared to other SaaS products:
- Fintech applications deal with highly sensitive user information (such as personal and financial data)
- Most fintech applications will require use of a regulated infrastructure (such as payment processing), such as PCI DSS, PSD2, AML/KYC Compliance, etc.
- Fintech applications must be highly available (they must be operational 24/7 – 365 days per year)
- The regulatory and market environments are constantly changing, and therefore, many of the technology stacks used by fintech applications will likely need to be updated on a very frequent basis
Thus, the technology stack used for fintech applications must provide security, traceability, perform well and be adaptable, while providing the ability to quickly develop and deliver application changes.
Let’s go into more detail about these factors.
The Safety & Performance of Back-End Languages
For the Fintech sector to excel, back-end languages need some fundamental characteristics that will allow them to meet the demands placed upon them: security, support, and auditing capability.
Back-End Tech Stack Recommendation:
- Typescript + Node.js: When used together, TypeScript provides for static type-checking combined with automated testing, allowing fast iteration while keeping the codebase secure. Typescript is also very effective when used in event-driven architectures and cloud-native applications.
- Go (Golang): Golang is increasing in popularity as a back-end language for creating high-performing APIs. Golang has a statically typed syntax, is fast and straightforward to use, making it an ideal choice for payment gateway APIs and/or microservice APIs.
- Java/Kotlin: Java and Kotlin continue to be the primary choice for enterprise-grade banks. Java and Kotlin also have a robust ecosystem to provide the necessary tools for the development of secure and compliant applications. Java and Kotlin are often used with the Spring Boot framework for building modern applications.
- Python: Python is well-suited for data-heavy applications in the fintech sector, such as risk analysis and machine learning. However, when using Python, it’s essential to have strong type-checking and automated testing done to reduce the risks associated with dynamic typing.
At Appricotsoft, we frequently recommend TypeScript or Go for clients requiring quick and secure development of their applications. If you plan to create third-party integrations or open banking APIs, we would recommend using lightweight, testable microservices as a back-end architecture.
The Connection Of Database Systems: Auditability And Structure
A database should have excellent transaction guarantees and an audit trail if you’re developing a Fintech application.
Database options available:
- PostgreSQL is the most commonly used database solution available. Its ACID-compliant (Atomicity, Consistency, Isolation, Durability) architecture, support for JSON datatypes, extensive audit trail functionality, and user-friendly design make it the best choice for transactional applications.
- MongoDB is also a viable option for applications that are being quickly constructed, but only if you have implemented a robust schema validation process first. It works well for logs, event stores, and storing metadata; however, it should never be used as a foundation for core financial systems.
- Redis can also provide you with solid performance for caching data and managing sessions, but it is not recommended for storing financial records.
- ClickHouse or BigQuery is a great analytic solution for real-time applicability, fraud detection, or reporting.
In addition, we want to make sure that the database that we choose conforms to any applicable legal or regulatory standards by adhering to the GDPR or PSD2 requirements.
Cloud Services: Scalability, Control And Compliance
The cloud provider that you use (AWS, GCP, or Azure) can greatly affect your Fintech product’s performance.
Key items to consider:
- If you plan to operate a multi-region cloud setup, it will adequately address your data residency obligations for data contained within the EU.
- Implementing Zero Trust Networking with Amazon VPCs, Firewalls and Security Groups will help keep your data secure against both external and internal attacks.
- There are several managed service options available for secret and key management in Cloud Services, including AWS Secrets Manager and Google Secret Manager.
- Compliance requires having an Audit Log and Version Control.
We will implement Infrastructure as Code (Terraform) for provisioning and auditing your cloud services and build CI (Continuous Integration) pipelines that include compliance checks starting on day one.
The Speed and Safety of CI/CD
With the correct pipeline, you can have both speed and safety without needing to compromise one for the other.
Tooling Recommendations:
- GitHub Actions or GitLab CI for versioned, repeatable builds.
- Automated code scanning (SonarQube/Snyk) to catch vulnerabilities early.
- Test coverage enforcement: unit, integration, and regression testing.
- Manual approval processes for production deployments (required by regulations).
Automated and visible tooling can aid in meeting regulators’ expectations of traceability and change management.
Observability – Because Uptime is Your Product
Logs, metrics, and traces are not simply nice to have; they are critical for illustrating success in the Fintech industry.
Our preferred stack:
- Prometheus + Grafana for collecting metrics and displaying them via dashboards.
- OpenTelemetry + Jaeger for tracking distributed systems.
- Elastic Stack or Loki for logging purposes.
We also create alerting systems (PagerDuty, Slack + Opsgenie) to allow us to respond quickly to incidents and create post-incident documentation for transparency.
Mobile Development Frameworks: Considerations for Native vs. Cross-Platform
Are you a mobile-first fintech company? You bet! But selecting the wrong mobile stack can delay you.
When to Use Native:
- If your application will have lots of device features (FaceID, NFC).
- If you need to implement a regulatory requirement that requires you to use a platform-specific feature.
- If your customers demand a high level of performance and UI.
When to Use Cross-Platform:
- When you will be creating applications with the same UI logic (onboarding, dashboards & alerts).
- When you are building an early stage MVP (minimum viable product) and do not have much budget.
- If you want to create the same functionality across iOS and Android.
Appricotsoft’s Recommendation: React Native. As a React Native app development company we have built Fintech apps that balance time to create and improve usability by allowing you to iterate on your applications without creating duplicate content.
We also provide our fintech clients with shared UI component libraries and design systems to help ensure consistency between the different platforms.
Compliance and Stacking Choices: What Entrepreneurs Often Miss
The following are the things compliance auditors will actually verify.
Audit Logs – who made a change to what and at what time (including changes to infrastructure).
Change Control Management – how your software code is enforced in the production environment.
Change Control Management on Your Configuration Settings — how your configuration files are controlled.
Encryption – how your data is secured while it is being processed and encrypted when it is stored and/or backed-up.
Access Control Policies (e.g., Role-Based Access Control, Multiple Factor Authentication, and Shared Credentials Not Allowed).
Code Quality – how your code has been produced by the developers and how much testing has been performed against it to ensure that the current functionality works appropriately.
Your Stack Will Have to Support:
✅ Immutable Builds
✅ Role-Based Access Control
✅ Clean Code History
✅ Automated Testing and Deployment Pipelines
✅ Secure Storage of Secrets
To ensure you do not need to remember to implement these controls each and every time you develop a new application, we build in these controls for each project using the AI-based Unison Delivery Framework.
How Your Stack Choice May Affect Scaling
Many startups utilize the stack that their original engineer works with. That’s alright until you grow.
The following are some warning signs we look for when working with stacks:
- A monolith that has no separation between the admin side and the end user side
- In-memory session storage in deployments with multiple instances
- No logging or monitoring beyond console.log
- Database writes were made without any sort of tracking for audits
At our company, Appricotsoft, we offer detailed Architecture Review & Practical Migrations services to alleviate these issues.
We will assist you through every aspect of Fintech discovery and planning, as having a good stack or way to build systems will not solve your problems by itself.
Conclusion: Build What is Coming
Fintech is constantly evolving, including all other areas of financial technology such as Embedded Financial Technology Products or Services, Distributed Ledger Technology (DLT) and Open Banking.
You will need to build your stack with this in mind. At Appricotsoft, we go beyond just building applications by assisting fintech founders in thinking a few steps ahead regarding the selection of proper technology and through assistance during the audit and compliance review process; we hope you will be ready to launch your application with confidence and grow your application as planned.