Sr. Software Engineer
onPhase · Florida, United States
- Hybrid
- Full-time
- $130,000 / year
- Florida, United States
Tailored resume — keyword-matched to this role.
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Job highlights
- Develop financial tech applications for enterprise clients.
- Maintain large-scale invoice and payment systems.
- Utilize advanced .NET Framework and .NET Core.
- Work with SQL Server and cloud storage.
- Collaborate on legacy modernization projects.
About the role
About the Role
We are seeking an experienced Senior Software Engineer to join our software development team working on mission-critical financial technology applications. You will be responsible for developing and maintaining large-scale invoice processing, accounts payable, and document management systems serving enterprise clients across multiple industries. The ideal candidate brings hands-on experience in financial or B2B software, with a strong understanding of AP/AR workflows, Payments systems, and broader Finance domain processes.
Finance Domain Experience - Strongly Preferred
Given the nature of our core products — invoice processing, vendor payment management, and AP automation — we place significant value on candidates with real-world experience in:
- Accounts Payable (AP) and/or Accounts Receivable (AR) software development or operational systems
- Payments platforms including ACH, wire transfer, virtual card, and payment processing workflows
- Invoice processing, purchase orders, remittance processing, and B2B document exchange (EDI)
- Financial Technology (FinTech) products serving enterprise or mid-market clients
- ERP integrations — SAP, Oracle, NetSuite, QuickBooks, Microsoft Dynamics, or similar
- Audit trail design, financial data integrity, and compliance-aware software development
- Spend management, treasury operations, or general ledger (GL) system connectivity
Technical Skills
Core .NET Technologies
- Advanced C# and VB.NET proficiency — mixed-language enterprise codebase.
- .NET Framework 4.6–4.8 — extensive experience with legacy .NET Framework applications.
- .NET 6/7/8 — modern .NET development for new platform initiatives
- ASP.NET Web Forms and MVC — maintain and enhance hybrid web applications
- ASP.NET Web API — build and maintain RESTful services and integrations
- Entity Framework — data access and ORM patterns (Code First and Database First)
- Windows Services — background processing services for document workflow automation
Web Technologies
- Blazor Server — build modern web UIs for SaaS platform
- AngularJS — maintain existing frontend components
- JavaScript/jQuery — legacy frontend maintenance with jQuery UI and validation
- XSLT transformations — XML-based templating systems
- Telerik UI Components — enterprise UI components for legacy and modern applications
- OAuth 2.0 & JWT — modern API authentication and security
Database & Data Technologies
- SQL Server — complex stored procedures, functions, and database design
- Database-first development — schema changes, migrations, and performance optimization
- ADO.NET — custom data access patterns and legacy integration
- Amazon S3 — cloud document storage and management
Architecture & Integration
- Multi-tenant SaaS architecture — customer-specific configurations and customizations
- EDI processing — Electronic Data Interchange (810, 850, 855, 856 transaction sets)
- File processing — CSV, XML, fixed-width file imports/exports
- SOAP/REST web services — external system integrations
- Payment processing integrations — financial system connectivity
DevOps & Infrastructure
- MSBuild and Visual Studio — build automation and deployment
- IIS deployment and management — Windows-based web application hosting
- Git version control — large enterprise codebase management
- PowerShell scripting — deployment and automation tasks
- Azure DevOps Pipelines — CI/CD with YAML configurations and automated testing
- NuGet Package Management — private Azure Artifacts feeds and dependency management
Preferred Qualifications
- Bachelor's degree in Computer Science or related discipline.
- 5+ years of .NET development experience
- Finance/FinTech background — hands-on AP, AR, Payments, or financial software experience strongly preferred
- Strong SQL Server database design and optimization skills
- Self-motivated with ability to navigate complex, large codebases
- Strong problem-solving skills for debugging and optimizing enterprise applications
- Excellent communication skills for collaborating with business stakeholders and QA teams
- Experience with legacy modernization and gradual migration strategies
Key skills/competency
- Senior Software Engineer
- .NET Development
- C#
- SQL Server
- Financial Technology
- AP/AR Automation
- SaaS Architecture
- Legacy Modernization
- DevOps
- Problem-Solving
Skills & topics
- Senior Software Engineer
- .NET
- C#
- VB.NET
- ASP.NET
- SQL Server
- Financial Technology
- FinTech
- AP Automation
- Accounts Payable
- Accounts Receivable
- Invoice Processing
- Payments Systems
- SaaS
- Enterprise Software
- Legacy Modernization
- DevOps
- Azure DevOps
- Blazor
- AngularJS
- Entity Framework
- Web API
- Windows Services
- Telerik UI
- OAuth 2.0
- EDI
How to get hired
- Tailor your resume: Highlight your .NET, SQL Server, and financial domain experience. Emphasize AP/AR, payment systems, and SaaS architecture skills.
- Showcase FinTech expertise: Detail your work with invoice processing, vendor management, and ERP integrations in your application.
- Prepare for technical interviews: Brush up on C#, .NET Framework/Core, SQL Server stored procedures, and RESTful API design.
- Demonstrate problem-solving: Be ready to discuss complex coding challenges and debugging scenarios related to enterprise applications.
- Communicate your value: Articulate how your skills align with onPhase's mission-critical financial technology solutions.
Technical preparation
Master C# and .NET Framework/Core concepts.,Practice complex SQL Server queries and optimization.,Build sample RESTful APIs with ASP.NET Web API.,Familiarize with SaaS and FinTech principles.
Behavioral questions
Describe a complex codebase you navigated.,Share an experience debugging enterprise applications.,How do you collaborate with stakeholders?,Explain a legacy modernization strategy you used.
Frequently asked questions
- What are the primary responsibilities of a Senior Software Engineer at onPhase?
- As a Senior Software Engineer at onPhase, your primary responsibilities will involve developing and maintaining mission-critical financial technology applications, including large-scale invoice processing, accounts payable, and document management systems for enterprise clients. You'll work with advanced .NET technologies and SQL Server, focusing on financial domain processes.
- Is experience in financial technology a must for this Senior Software Engineer role?
- While not strictly mandatory, hands-on experience in financial or B2B software, particularly with AP/AR workflows, payments systems, and the broader finance domain, is strongly preferred for this Senior Software Engineer position at onPhase. This includes experience with invoice processing and ERP integrations.
- What .NET technologies are most important for this Senior Software Engineer position?
- The Senior Software Engineer role at onPhase heavily utilizes core .NET technologies. This includes advanced C# and VB.NET, extensive experience with .NET Framework 4.6-4.8, and modern .NET 6/7/8 development. Proficiency in ASP.NET Web Forms, MVC, Web API, and Entity Framework is also crucial.
- What kind of database experience is required for the Senior Software Engineer at onPhase?
- Strong SQL Server database design and optimization skills are highly valued for this Senior Software Engineer role. You should be comfortable with complex stored procedures, functions, database-first development, and performance optimization within SQL Server.
- How does onPhase handle legacy modernization for its financial applications?
- onPhase likely employs gradual migration strategies for legacy modernization. As a Senior Software Engineer, you may be involved in enhancing hybrid web applications (ASP.NET Web Forms/MVC) and maintaining legacy frontend components while contributing to new platform initiatives using modern .NET and Blazor Server.
- What are the typical work arrangements for a Senior Software Engineer at onPhase?
- While the job description doesn't explicitly state the work arrangement, similar roles in enterprise software development often involve a hybrid model. However, without explicit details, it's safest to assume an on-site or potentially remote arrangement depending on team needs and company policy.
- Can I apply for the Senior Software Engineer role if I don't have a Bachelor's degree but have significant experience?