C#/.NET Engineer – ERP and QuickBooks Integration

C#/.NET Engineer – ERP & QuickBooks Integration

Location: Ukraine — 100% Remote
Employment Type: Full-Time
Salary: $2,000–$2,500 USD/month
Required Working Hours: U.S. Eastern Time (ET)

About the Role
We are looking for an experienced C#/.NET Engineer based in Ukraine to join our development team and work primarily on ERP development and QuickBooks integrations.
This is a remote position, but candidates must be available to work U.S. Eastern Time business hours. This requirement is important because the engineer will collaborate directly with our U.S.-based engineering team, customers, and business stakeholders.
You will build and maintain backend services, APIs, synchronization processes, and integrations connecting our ERP platform with QuickBooks and other business systems.

Responsibilities
Develop and maintain backend applications using C# and .NET / .NET Core.
Build and maintain ERP integrations with QuickBooks.
Develop integrations with QuickBooks Online (QBO) APIs.
Work with customers, vendors, invoices, payments, bills, expenses, purchase orders, accounts, payroll-related data, and inventory.
Design reliable two-way data synchronization between ERP and QuickBooks.
Build REST APIs, webhooks, background services, and scheduled synchronization jobs.
Implement OAuth 2.0 and other authentication mechanisms.
Handle data mapping and transformation between ERP and QuickBooks.
Troubleshoot synchronization failures, duplicate records, API errors, and data inconsistencies.
Implement retry mechanisms, logging, monitoring, and error handling.
Work extensively with SQL Server and relational data.
Investigate and resolve production integration issues.
Participate in code reviews and architecture discussions.
Collaborate directly with U.S.-based developers, product managers, customers, and stakeholders.
Participate in meetings and technical discussions during U.S. Eastern Time working hours.

Required Technical Skills
3+ years of professional C#/.NET development experience
Strong C# programming skills
.NET 6/7/8 or later
ASP.NET Core / Web API
REST API development and third-party integrations
SQL Server
Entity Framework / Entity Framework Core
OAuth 2.0
JSON and API data transformation
Background workers and scheduled jobs
Asynchronous programming (async / await)
Git
Strong debugging and troubleshooting skills

ERP & QuickBooks Experience
Experience in one or more of the following is strongly preferred:
QuickBooks Online API
QuickBooks Desktop integrations
QuickBooks Web Connector
ERP development
Accounting system integrations
Customer/vendor synchronization
Invoice and payment synchronization
Payroll integrations
Inventory and purchasing workflows
CRM-to-accounting integrations
Financial data synchronization

Previous QuickBooks integration experience is highly preferred.
Nice to Have
Microsoft Azure
Azure Functions
Azure App Service
Azure SQL
Azure Service Bus
Docker
CI/CD
GitHub Actions or Azure DevOps
Microservices
Message queues
Redis
Vue.js, Angular, or React
Multi-tenant SaaS experience
Experience modernizing legacy .NET applications

Working Hours — Important
This position requires working according to the U.S. Eastern Time (ET) schedule.
Candidates must be comfortable working U.S. business hours from Ukraine and should be consistently available during the agreed Eastern Time schedule for:
Daily development work
Team meetings
Customer meetings
Technical discussions
Production support
Collaboration with U.S.-based team members

Please apply only if you are comfortable working U.S. Eastern Time hours on a long-term basis.

What We're Looking For
We need an engineer who can take ownership of integrations from beginning to end: understand the business workflow, review third-party API documentation, design the solution, implement it, test it, deploy it, and troubleshoot production issues.
Because this role involves accounting and financial data, accuracy, reliability, data integrity, logging, and robust error handling are critical.
Strong English communication skills are also important because you will regularly communicate with U.S.-based team members and potentially customers.