Senior Software Engineer | Python / C# / AWS (LATAM)

Upstart AEC is seeking a Senior Software Engineer to support critical data ingestion and processing workflows within a high-volume financial technology platform. The role combines backend development, performance optimization, and system modernization. You will work with C#/.NET services while helping build new Python-based AWS Lambda, microservices, and Step Functions solutions. The ideal candidate is comfortable with both Python and C#, experienced with performance-sensitive systems, and able to work effectively through technical debt, changing priorities, and complex production issues.

Key Responsibilities

• Develop and maintain backend services in Python and C#/.NET.
• Build serverless services using Python, AWS Lambda, and related AWS technologies.
• Support the evolution toward scalable microservices and serverless architecture.
• Develop and optimize high-volume data ingestion and processing workflows.
• Diagnose performance issues, bottlenecks, race conditions, and distributed-system failures.
• Optimize application code, database queries, and processing workflows.
• Work with SQL-based systems, DynamoDB, and PostgreSQL.
• Develop reliable APIs and AWS-based solutions using Lambda, S3, and Step Functions.
• Investigate production issues and communicate root causes and trade-offs clearly.
• Review unfamiliar code and documentation before making changes.
• Participate in code reviews, documentation, and responsible use of AI-assisted development tools.
• Collaborate across squads and support other engineers when needed.

Required Skills

• 5+ years of professional software development experience.
• Strong experience with both Python and C#/.NET.
• 4+ years designing or operating cloud-native AWS applications.
• Hands-on AWS Lambda and serverless development experience.
• Strong SQL skills, including query optimization and performance troubleshooting.
• Experience with relational databases and high-throughput data processing.
• Understanding of concurrency, retries, idempotency, failure handling, and service dependencies.
• Proven experience improving application performance in production.
• Strong problem-solving, communication, and collaboration skills.
• Ability to work with unfamiliar or legacy codebases.
• Comfortable with technical debt, shifting priorities, and urgent production needs.
• Experience evaluating and correcting AI-generated code.

Nice-to-Have Skills

• AWS Step Functions, S3, API Gateway, EventBridge, SQS, or SNS.
• DynamoDB and PostgreSQL experience.
• Identity and access management, including JWT authentication.
• Infrastructure as code with Terraform or CloudFormation.
• Observability tools such as CloudWatch, Datadog, or AWS X-Ray.
• Experience mentoring junior or mid-level engineers.