Software Engineer, Payments (.NET / Vue.js)

Neumo Holdings LLC• Bloomington, NH, US, TX

About The Position

The individual in this role will design, build, test, and maintain features for our payments platform, including the web-based merchant portal and checkout experiences, backend services and APIs, and integrations with physical payment terminals and payment processors. The Software Engineer works across the stack (.NET 8, Vue.js, and Azure Table and Blob Storage) to deliver reliable, secure, and well-tested software that accurately moves money. Competitive candidates have [3+] years of professional software development experience, ideally on transaction-processing or other high-reliability systems.

Requirements

3-6 years of professional software development experience
Building and maintaining web applications and REST APIs
Working within Agile or Scrum teams, including code reviews and version control workflows
Writing automated unit and integration tests
Proficiency in C# and .NET (.NET 8 preferred), including ASP.NET Core web APIs
Experience with a modern JavaScript front-end framework, preferably Vue.js, along with HTML, CSS, and TypeScript or JavaScript
Experience with cloud-based or NoSQL data storage, such as Azure Table Storage, Blob Storage, or similar
Experience with Git-based source control and CI/CD pipelines (e.g., Azure DevOps or GitHub Actions)
Strong understanding of software design principles, including API design, asynchronous processing, error handling, and distributed systems concepts.
Working knowledge of payment flows and concepts, including authorization, settlement, chargebacks, refunds, reconciliation, tokenization, and encryption, or the ability to learn them quickly.
Understanding of the trade-offs of working with non-relational storage, such as eventual consistency, limited transaction support, and query design driven by partition and row keys.
Strong debugging and troubleshooting skills across web, API, data, and device layers.
Highly organized and detail-oriented, with particular care where money movement or customer data is involved.
Ability to prioritize and manage multiple tasks with composure, including time-sensitive production issues affecting merchants.
Ability to maintain a positive and professional attitude in a fast-paced environment.
Ability to work independently and as a contributing member of a team.

Nice To Haves

Experience in payments, fintech, or financial services
Experience with the Microsoft Azure ecosystem, including Azure Functions, Service Bus or Queue Storage, Key Vault, Application Insights, and Log Analytics
Knowledge of PCI DSS and secure software development practices

Responsibilities

Translate business requirements and payment processes (authorization, capture, void, refund, settlement, reconciliation) into technical designs and working software.
Design, develop, and maintain backend services and APIs using C# and .NET 8, including payment, webhook, and reporting endpoints.
Build and maintain front-end features in Vue.js for the merchant portal, hosted checkout, and admin tools, with attention to usability, accessibility, and cross-browser behavior.
Design and implement data models and access patterns in Azure Table Storage and Blob Storage, including partition and row key design, query performance, and data retention.
Build integrations with payment processors, gateways, and terminal software, handling asynchronous responses, timeouts, retries, and error conditions gracefully.
Design for idempotency, data consistency, and fault tolerance so that duplicate requests, network failures, and partial failures never result in incorrect charges or lost transactions.
Support terminal-related development, including communication between terminals and the platform, offline or store-and-forward scenarios, and firmware and application update workflows.
Write clean, maintainable, and well-documented code, and participate in code reviews, design discussions, and architecture decisions.
Write unit, integration, and automated tests, and partner with QA to ensure features are testable and thoroughly validated before release.
Investigate and resolve defects, including issues escalated by the support engineering team, using logs, monitoring, and transaction data to identify root causes.
Collaborate with the support engineering team to improve diagnostics, logging, and internal tooling so that transaction lookups and issue investigations are faster and more reliable.
Follow secure coding practices and PCI DSS requirements, including protection of cardholder data, encryption, tokenization, secrets management, and access controls.
Support certification and compliance efforts, such as card brand, EMV, acquirer/processor, and PCI-related requirements.
Contribute to CI/CD pipelines, deployments and release readiness, and support post-release monitoring.
Monitor application performance and reliability, and improve performance, scalability, and cost efficiency in Azure.
Identify technical debt and recurring problem areas and recommend and implement improvements.
Independently own a workstream or product area (for example, terminal integration, merchant portal, or payment APIs), from design through deployment and ongoing support.
Participate in daily engineering meetings to update teammates and management on status.
Present technical expertise in training, implementation, and cross-team environments as needed.
Perform other duties as assigned.