Senior Full-Stack Developer

Company Description LVJ Soft helps organizations optimize software development and operations, adopt transformative technologies, and drive sustainable growth. The company focuses on delivering actionable insights and practical implementations that improve engineering efficiency and product quality.

We are looking for a Senior Full-Stack Engineer to join an established and rapidly growing FinTech platform. This is a hands-on senior individual-contributor role with broad technical ownership across mobile applications, backend services, databases, and AWS infrastructure.

The ideal candidate can work across the full application stack, troubleshoot complex production issues, and improve performance, security, reliability, and scalability as the platform grows.

Key Responsibilities

• Develop and maintain cross-platform mobile applications using React Native for iOS and Android.
• Build and maintain backend services using Python and C#/.NET.
• Develop and maintain REST APIs and third-party integrations.
• Optimize MySQL queries, indexes, schemas, and database performance.
• Support and improve AWS production infrastructure and CI/CD pipelines.
• Troubleshoot issues across mobile, backend, database, and cloud infrastructure.
• Improve application performance, scalability, security, and operational reliability.
• Review code, document critical workflows, and contribute to architectural improvements.

Requirements:

• 7+ years of professional software engineering experience, or equivalent demonstrated senior-level experience.
• Strong hands-on experience with React Native for both iOS and Android.
• Strong backend development experience with Python and C#/.NET.
• Experience developing and maintaining ASP.NET Core REST APIs, services, or microservices.
• Strong knowledge of REST APIs and MySQL or similar relational databases.
• Hands-on AWS production experience, particularly with EC2, RDS, IAM, and VPC.
• Experience with CI/CD, Git, code reviews, and production troubleshooting.
• Strong understanding of application security, performance optimization, and scalable system design.
• Ability to work independently with an existing production codebase and take ownership across multiple technical layers.

Preferred Qualifications:

• FinTech, banking, payments, lending, or financial-data integration experience.
• Experience with Node.js, JavaScript, or TypeScript backend services.
• Experience with AWS S3, SQS, Lambda, API Gateway, KMS, and Secrets Manager.
• Experience with microservices, load testing, capacity planning, and application security testing.
• Important: This role is not limited to mobile, frontend, or backend development alone. We are looking for an engineer who can understand and troubleshoot the system as a whole.