Senior Backend Developer – C#

Job Title: Senior Backend Developer – C\# / .NET 8/9 \& AWS Serverless (Stripe \& Integrations) Job Type: Short\-Term Contract / 1099 Location: Remote (US) Schedule: Full\-time Duration: Short\-Term Project (Immediate Start) About the Position: We are seeking a Senior C\# / .NET Backend Developer for an immediate\-start, short\-term contract position on a US HealthTech platform. You will be stepping in to take full technical ownership of our serverless backend architecture. You'll be maintaining and building critical features around complex Stripe billing engines, third\-party vendor integrations (OAuth2, Firebase, Checkr), and AWS infrastructure. What You Will Do: * Daily development in C\# / .NET (8/9\) within a production AWS Serverless stack. * Maintain and refine complex server\-side Stripe logic (webhooks, custom invoice items, two\-stage shift counting, and tier\-crossing subscription models). * Build and manage server\-to\-server integrations (Firebase Admin SDK, OAuth2 workflows, pending Checkr integration). * Manage relational DB design and queries via EF Core. * Maintain IaC templates using AWS SAM, CDK, or CloudFormation (Lambda, API Gateway, S3, Secrets Manager, CloudWatch/X\-Ray). * Maintain high standards for code review, PR discipline, and credential isolation. Requirements: * 5\+ years of experience in C\# / .NET development (experience with .NET 8/9 required). * Strong expertise in AWS Serverless services (Lambda, API Gateway, Secrets Manager, IAM, CloudWatch/X\-Ray). * Deep experience implementing complex server\-side Stripe billing (custom subscription logic, webhooks, invoice items). * Proficiency with EF Core and relational database modeling. * Experience with server\-side SDKs and third\-party API integrations (Firebase, OAuth2\). * Strong Git/GitHub PR discipline and security practices. * Ability to onboard quickly and work independently with minimal hand\-holding. * Full professional English proficiency. Preferred Skills: * HealthTech or workforce/shift management domain experience. * Direct experience with Checkr integration. To Apply: Please submit your resume along with a brief summary of your experience with C\# / .NET 8/9, AWS Serverless, and custom Stripe server\-side integrations. Pay: $60\.00 \- $75\.00 per hour Expected hours: 20\.0 per week Application Question(s): * Do you have direct experience with server\-side Stripe integrations (webhooks, subscriptions, and custom tier billing) on AWS Serverless? Work Location: Remote