About the Role

We are looking for a Senior Full Stack Developer to join our engineering team and help build and complete revenue-critical financial technology workflows. You will work across the .NET backend, React/TypeScript frontend, PostgreSQL data layer, APIs, asynchronous integrations, and Azure platform. The role is hands-on and suited to an engineer who can take ownership of complex workflows from database and API design through frontend experience, automated testing, deployment, and production support.

What You Will Own

· End-to-end development of financial transaction, account, payment, beneficiary, reporting, and reconciliation workflows.

·   C#/.NET services and REST APIs, including validation, authorization, idempotency, retries, state transitions, and error handling.

· React and TypeScript merchant and operational interfaces with clear handling of pending, failed, rejected, returned, reversed, cancelled, and completed states.

· PostgreSQL database design, relational data modeling, transactional integrity, performance, and audit-friendly data structures.

· Integration with third-party payment and financial providers, including webhooks, provider references, status mapping, timeouts, retries, and reconciliation.

·  Double-entry ledger-related workflows for transactions, fees, holds, reversals, adjustments, collections, payouts, and pay-ins where applicable.

·   Automated testing across unit, integration, contract, API, end-to-end, replay, duplicate, timeout, and negative-path scenarios.

· Deployment and operational support within the existing Azure environment, working closely with DevOps and platform engineering.

Key Responsibilities

· Design, develop, debug, and complete existing workflows without defaulting to unnecessary rewrites.

· Build secure, versioned, reliable APIs using C#/.NET and PostgreSQL.

· Develop responsive and operationally effective React/TypeScript interfaces integrated with backend transaction states.

· Implement safe idempotency and retry behavior so duplicate requests cannot create duplicate financial movements.

· Implement explicit transaction and balance states and ensure valid state transitions.

· Capture provider request/response evidence, provider IDs, event IDs, timestamps, correlation IDs, payload hashes, and immutable status history where required.

· Verify webhook authenticity, deduplicate events, handle replay and out-of-order events, and manage provider failures gracefully.

· Use reversal, adjustment, or correction entries rather than destructive updates for financial records.

· Implement role-based access control, permissions, authentication, and secure handling of sensitive operations.

· Work with QA to create meaningful automated coverage, especially for failure, duplicate, timeout, return, reversal, and reconciliation scenarios.

· Investigate production issues using application logs, database state, provider evidence, and monitoring data.

· Collaborate with Product, QA, DevOps, Operations, Compliance, and other engineers to deliver production-ready features.

Required Skills & Experience

· 5+ years of professional software engineering experience, with strong full-stack development experience.

· Strong hands-on experience with C# and modern .NET / ASP.NET Core.

· Strong React and TypeScript experience, including component design, forms, tables, state management, and API integration.

· Strong PostgreSQL and relational database development skills, including schema design, queries, transactions, indexing, and performance tuning.

· Solid experience designing and consuming REST APIs and versioned API contracts.

· Practical experience with asynchronous processing, queues, retries, webhooks, distributed systems, and state-machine-style workflows.

· Strong understanding of authentication and authorization, including OAuth/OIDC, roles, permissions, API keys, or equivalent mechanisms.

· Experience writing automated unit and integration tests and contributing to end-to-end testing.

· Ability to debug complex production workflows across frontend, backend, database, integrations, and infrastructure.

· Strong understanding of clean code, SOLID principles, design patterns, code review, Git, and engineering best practices.

Strongly Preferred

· Experience in FinTech, payments, banking, treasury, accounting, money movement, or other financial systems.

· Experience with double-entry accounting or immutable financial ledgers.

· Experience with payout, pay-in, ACH, wire, SWIFT, FX, stablecoin, collections, or reconciliation workflows.

· Azure experience with AKS/App Services, Azure Service Bus, Key Vault, Blob Storage, managed identity, monitoring, and application insights.

· Experience integrating imperfect or inconsistently documented third-party APIs.

· Experience with CI/CD pipelines and Azure DevOps.

· Experience with Playwright, Cypress, Postman/Newman, Pact, or similar testing tools.

· Experience working in regulated or compliance-sensitive environments.

What Good Looks Like

· You understand that a provider-submitted transaction is not necessarily a settled transaction.

· You design retries and idempotency so financial operations remain safe under duplicate requests and provider replays.

· You clearly distinguish failed, rejected, returned, cancelled, reversed, pending, processing, and completed outcomes.

· You treat auditability, reconciliation evidence, and data integrity as part of the product definition of done.

· You can explain how a transaction moves from API request through provider processing, ledger posting, reconciliation, and final status.

· You build frontend experiences that make financial uncertainty and operational exceptions clear rather than hiding them behind generic statuses.

· You are comfortable owning a feature end-to-end and working hands-on across the stack.

Technology Environment

· Backend: C#, .NET / ASP.NET Core, REST APIs

· Frontend: React, TypeScript

· Database: PostgreSQL

· Cloud & Platform: Microsoft Azure, AKS / App Services, Service Bus, Key Vault, Blob Storage

· Engineering: Git, CI/CD, automated testing, observability and production support

· Integration: Third-party financial/payment providers, webhooks, asynchronous messaging and reconciliation

Why Join Us?

· Work on technically challenging, revenue-critical financial technology.

· Own features across the complete technology stack rather than being limited to a single layer.

· Solve real-world problems involving payments, distributed systems, reconciliation, data integrity, and provider integrations.

· Work with an experienced engineering team and collaborate across product, engineering, QA, operations, compliance, and platform teams.

· Have a direct impact on building reliable and scalable financial infrastructure.

How to Apply

If you are a senior full-stack engineer who enjoys solving complex engineering problems and wants to work on financial technology where correctness, reliability, and engineering quality matter, we would love to hear from you.