WislaCode

Fintech Software Development

We partner with banks, insurers, payment providers and fintechs to design, build and integrate custom financial software. Our focus is custom engineering and implementation within your environment. WislaCode create secure, resilient systems that improve customer experience and operational efficiency while aligning with regulation and your risk posture.

Financial software development services

We provide greenfield platforms, update old systems, and enhance current solutions with new features.

Engagements are shaped around your architecture – core banking, payments, identity, risk, treasury, analytics. So change strengthens daily operations without vendor lock‑in.

Security, privacy and compliance are embedded throughout the lifecycle.

Product‑grade fintech app engineering

We design and evolve financial applications across web and mobile, prioritising performance, accessibility and secure data handling. From onboarding and KYC to payments, statements and servicing, we engineer reliable journeys with audit trails, idempotent operations and deep observability. Releases follow a secure SDLC with progressive delivery for safe, frequent updates.

Security information and event management (SIEM)

We design SIEM pipelines that correlate application, API gateway and infrastructure logs. High‑fidelity alerts reduce noise while detecting credential abuse, anomalous transfers and data‑exfiltration attempts. Detection rules evolve with threat intelligence; runbooks accelerate incident response and recovery.

Applied AI and machine learning

We deliver pragmatic AI/ML for financial services: risk scoring, anomaly detection, document processing and personalisation. Data pipelines include lineage, quality checks and bias monitoring. Models are served behind auditable interfaces with human‑in‑the‑loop controls where appropriate.

Identity and access management (IAM) for finance

We implement IAM to financial‑grade standards: fine‑grained authorisation, adaptive MFA and consent management. Strong customer authentication patterns are applied to critical actions, with central policy enforcement and tamper‑evident logs to support compliance and investigations.

API integration and open banking connectivity

We expose and use APIs with clear contracts and versioning. We also use gateways for rate limiting, schema validation, and threat protection. For open banking and PSD2 scenarios, we implement consented access, TPP onboarding controls and testable sandboxes – improving partner time‑to‑integrate while maintaining safeguards.

Integrated financial instruments and payment rails

We integrate cards, instant payments, bank transfers and wallets with explicit state models to prevent duplicate postings. Reconciliation services match authorisations, captures, settlements and fees, surfacing exceptions with full context to operator queues.

Custom fintech modules and platforms

Custom fintech modules and platforms

Streamlined operations, data‑informed decisions and improved CX across retail, commercial and investment use cases – delivered as targeted applications or cohesive digital ecosystems.

→ More about development Banking Software

Automated origination, pricing, collections and end‑of‑term flows for equipment and automotive finance, integrated with core platforms and dealer networks.

→ More about development Leasing Software

Real‑time market data processing, risk analytics and portfolio management capabilities to support informed decision‑making and compliance.
Advanced analytics over sensitive datasets to optimise processes and service quality, with strong governance, access controls and auditing.

Full‑cycle billing and mobile payments with detailed transaction reporting, dunning and dispute workflows – built for multi‑device continuity.

→ More about Billing and Payment Solutions

Enterprise‑grade software designed around the needs of banking, financial services and insurance, integrated with your existing estate.

→ More about Financial Solutions Development

Viacheslav Kostin
CEO WislaCode Solution

Ready to develop something unique?

Let's start the conversation and develop your own unique project.

How we deliver fintech software?

We dive deep into our clients’ businesses to create fintech solutions that align with their strategic goals, ensuring scalability and a future‑ready IT infrastructure.
Planning
Analysis

Testing, usability, performance and security – ensuring that the financial software and application are reliable, efficient and safe for users.

Testing
UX Research
Our commitment to quality includes comprehensive testing in functionality, usability, performance, and security, ensuring our financial software development services deliver robust applications.
Design
Development
Our solutions are built to scale and keep your application running smoothly, supporting your business for the long haul.
Launch
Support
Case: launching a compliant, scalable financial platform

A growth‑stage provider asked us to transform an early prototype into a production‑ready platform.

We re‑architected the core, implemented SCA‑ready IAM, introduced an API gateway and built reconciliation workflows across multiple payment methods. With progressive delivery and comprehensive observability, incident rates fell while weekly releases became standard.

The platform now supports consented data access, partner integrations and accelerating the roadmap without sacrificing control. This was a custom implementation within the client’s environment, not an off‑the‑shelf product.

Why WislaCode?
Security, traceability and consent management are embedded from day one. Strong authentication, immutable audit trails and change governance reduce compliance risk while maintaining delivery momentum.
Regulatory‑ready
Operational excellence baked in observability, resilience and disaster recovery are treated as first‑class features. Clear SLOs, tested failover and actionable dashboards keep platforms reliable and cost‑efficient at scale.
Cost‑efficient at scale
We decouple legacy dependencies via gateways and adapters, enabling new services to ship while back‑office systems evolve. Sandboxes and conformance tests shorten partner onboarding.
Integrations
Domain‑driven analysis, measurable milestones and progressive delivery let us ship value quickly – without compromising security, maintainability or user experience.
Progressive delivery

FAQ About Fintech Software Development

Financial platforms must prioritise transactional integrity, consented data access, and rigorous auditability. Architectures handle high‑throughput events with low latency and idempotent operations to avoid duplicates. Identity, authorisation, and strong customer authentication sit across critical journeys, and every sensitive action is logged. Integration spans core systems, payment gateways, and third‑party providers via API gateways with versioning and policy enforcement. Delivery pipelines add secure SDLC controls, segregation of duties, and traceable change management suited to regulated contexts. Reliability, observability, and disaster recovery are built in from the start. They include clear RTO and RPO targets. The result is resilient, compliant software that supports payments, account services, reporting, and partner ecosystems at scale.
We implement an API‑first approach with explicit contracts, schema validation, and consistent versioning. Gateways apply rate limiting, threat protection, and consent enforcement, while service‑to‑service authentication secures internal traffic. For open banking/PSD2, we deliver consent flows, TPP onboarding and verification, and testable sandboxes, aligning with ecosystem terminology such as AISP, PISP, and SCA from open banking resources. Read/Write API behaviours are observable end‑to‑end, with tamper‑evident audit trails for access requests and payment initiation. Progressive rollout and conformance testing reduce integration risk. This balance preserves developer experience and interoperability, while maintaining robust control across data sharing and payment flows.
Security is embedded from discovery to operations. We run threat modelling for domain‑specific risks, apply SAST/DAST and dependency scanning, and validate infrastructure as code. Secrets management, encryption in transit and at rest, and least‑privilege access are standard. CI/CD pipelines enforce quality gates and traceability, preventing promotion of artefacts that fail security or compliance checks. In production, SIEM correlates logs from applications, APIs, and infrastructure, with tuned detections for anomalous transfers and privileged activity. Incident playbooks and rehearsals accelerate response and recovery. Audit trails cover sensitive actions to support investigations and regulatory reviews, ensuring continuous assurance without slowing delivery.
We design for reliability at multiple layers. Stateless services and horizontal scaling manage variable loads; durable data stores with replication protect integrity. Queues and event streaming smooth peaks and isolate bottlenecks. We define SLOs for key journeys and use error budgets to guide releases. Load and chaos testing validate capacity and failure modes before traffic ramps up. Disaster recovery is verified through drills, with RTO/RPO targets agreed early. Cost-to-serve is tracked through telemetry and rightsizing. This keeps things efficient while maintaining a good user experience. Clear runbooks and dashboards keep operations predictable as volumes grow.
We treat data as a product with defined ownership, versioned contracts, and pipeline checks. Lineage tracks each transformation from source events to analytics and reporting. Quality rules monitor completeness, accuracy, and timeliness, with alerts routed to issue queues. Personally identifiable and sensitive fields are classified, masked where appropriate, and governed by retention policies. Reconciliation processes compare operational events with ledger entries and settlements to prevent drift. For reporting, we maintain traceability back to raw data, enabling defensible figures and faster audits. This governance model reduces defects and supports trustworthy insights.
Small teams own clear domains and release via trunk‑based development with short‑lived branches. Test suites cover unit, contract, integration, and end‑to‑end paths; environment parity reduces surprises. CI/CD pipelines enforce gates for security, performance, and compliance. Feature flags, canaries, and blue‑green deployments limit blast radius. After release, we keep an eye on key indicators like latency, error rates, and abandonment. This helps us spot problems early. Reference components for consent management, audit logging, and payment connectors speed delivery while preserving consistency and control.
We implement explicit payment state models and idempotent operations to avoid duplicates. Connectors to schemes and gateways run behind an API gateway with retries, back‑off, and circuit breaking. Events capture authorisations, captures, refunds, chargebacks, and fees for downstream reconciliation. Exceptions surface to operator queues with full context and audit history. Reporting paths are validated against control totals, maintaining financial accuracy and regulatory confidence. This approach reduces operational risk and improves transparency across the payment lifecycle.
Yes. We focus on high‑value applications such as anomaly detection, risk scoring, document processing, and personalisation. Data pipelines include lineage and quality checks; model governance covers versioning, performance monitoring, and bias evaluation. Sensitive features are minimised; human‑in‑the‑loop is used where necessary. Models are deployed behind auditable services with rate limits and rollback strategies. This enables meaningful automation and insight while preserving explainability, control, and compliance.

Viacheslav Kostin

Viacheslav Kostin, CEO

20+ years of experience in managerial positions in IT and banking.

Viacheslav Kostin, CEO
Previous roles: CEO in IT, Director of Strategy and Marketing in Banking, Curator of Holding Banks, Head of Products and Project Office.
Education: MBA for Executives at IMD (Switzerland), Leading Digital Business Transformation (IMD). Provides consulting in strategy and digital transformation.

Pahomov

Vasil Pahomov, CTO

20+ years of experience as a developer, analyst, and solutions architect.

Vasil Pahomov, CTO
Designs resilient, high-load systems with multiple integrations for banks and financial institutions. Expertise in distributed storage and microservices architecture.
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Let's discuss your project's evolution.
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