Senior Software Engineer $150k - $200k base 6 Denver, CO

We have multiple openings for Senior Software Engineers to join our core development team. As a Senior Software Engineer at our fintech startup, you will design and build critical components of our account-to-account payments platform. You will be working on a modern tech stack to develop features that might include everything from customer onboarding and bank account connectivity, to payment transaction processing, fraud detection integrations, and user-facing dashboards. This is a hands-on engineering role with broad ownership: one day you might implement a new API endpoint or microservice, and the next day you debug a complex issue across the stack or refine our CI/CD deployment pipeline. In this early-stage environment, engineers aren 77t siloed— expect to work across the stack and touch various aspects of the system. Some of our engineers focus more on backend (building out our secure RESTful APIs, database schemas, and external integrations), while others drive frontend efforts (creating intuitive web interfaces for our clients and perhaps refining our embeddable bank connection widget). We value versatility: a willingness to learn new technologies and pitch in where needed. You will collaborate closely with product managers to understand requirements, and with designers to ensure the UI is polished and user-friendly. Security, reliability, and performance are paramount in fintech, so you will incorporate best practices for handling sensitive financial data and ensuring high uptime. As a senior member of the team, you will also help set coding standards, mentor less-experienced developers, and influence architecture decisions. We operate in a fast-paced, agile fashion: shipping iteratively, gathering feedback, and continually improving. This role is full-time in Denver, CO with hybrid/remote flexibility. We offer a competitive base salary, benefits, and equity participation. If you are excited by building complex systems in a startup setting and seeing the direct impact of your code in the product, we would love to hear from you. Key Responsibilities Design & Develop Features – Implement new features and services for our platform end-to-end, ranging from back-end logic (e.g., creating a service for handling ACH payment requests with proper verification) to front-end interfaces (e.g., building a section of the customer dashboard for viewing transaction history). Build Scalable APIs – Create and maintain RESTful APIs that are secure, well-documented, and easy for clients to integrate. Ensure our API endpoints (customer creation, payments, identity verification, etc.) are efficient and handle errors gracefully. Integrate External Services – Work with third-party integrations critical to our fintech product. Integrate open-banking APIs (Plaid, Finicity, MX) for bank data, or identity verification services for KYC. Handle webhooks and callbacks from these services reliably. Database & Systems Management – Design relational database schemas to store customers, accounts, transactions, and more. Write efficient queries and optimize where necessary. Contribute to decisions on data storage solutions (SQL vs NoSQL, caching strategies). Quality Assurance – Write unit, integration, and end-to-end tests to ensure code quality and prevent regressions. Participate in code reviews, provide feedback, and maintain a high standard of engineering excellence. Debug and resolve production issues with root cause analysis and fixes. DevOps & Deployment – Contribute to build and deployment processes. Create CI/CD pipelines or scripts to automate testing and deployment. Containerize services (e.g., Docker) and work with infrastructure-as-code tools to manage cloud resources. Ensure applications are monitored and logging is in place for quick issue identification. Security & Compliance – Implement security best practices at every layer, including authentication/authorization in APIs, encryption of sensitive data, protection against common vulnerabilities, and fintech compliance standards (PCI, SOC2 relevant controls). Collaboration & Mentorship – Work with cross-functional teams, understand requirements from the Product Lead, iterate on UI with the Design Lead, and coordinate data needs with the Data Science team. As a senior engineer, mentor junior developers through pair programming, code reviews, and knowledge sharing. Architecture & Innovation – Participate in high-level architecture discussions. Evaluate new technologies or frameworks, identify refactoring opportunities and tech debt, and prototype ideas to improve performance or capabilities. Required Qualifications Strong Coding Skills – 5+ years of professional software development with primary focus on .NET and TypeScript. Proficient in building robust backend services and modern web apps using C#, TypeScript, and (optionally) Python. Familiar with architectural and design patterns such as CQRS, IoC, Clean Architecture, DDD, SOLID. Experience with Entity Framework and AutoMapper; quick to learn new technologies. Database Knowledge – Strong SQL and relational databases experience (designing schemas, querying, tuning). Experience with PostgreSQL, MySQL, etc. Familiarity with ORM and caching. NoSQL exposure is a plus. Distributed Systems & API Integration – Experience integrating external APIs and services. Familiarity with message queues or asynchronous processing for workflows and handling webhooks. Problem Solving – Excellent debugging and problem-solving across the stack. Ability to break down complex problems and provide practical solutions. Experience with performance tuning and scaling. Best Practices & Testing – Strong understanding of version control, code reviews, testing methodologies, and agile development. Ability to write clean, maintainable code and advocate for standards. Security Mindset – Knowledge of secure coding practices, authentication/authorization, encryption, data privacy, and fintech compliance considerations. Communication & Teamwork – Strong communication and collaboration in an agile environment with product, QA, and other engineers. Comfortable with feedback. BS/MS in Computer Science or equivalent experience. Preferred Qualifications Fintech or Payments Experience – Prior work on financial systems, payment processing, or banking software; familiarity with PCI, reconciliation, ACH, gateways, etc. Open Banking & Financial APIs – Experience with Plaid, Stripe, PayPal, or similar; understanding bank auth flows, tokens, and secure data transfer between systems. Cloud Infrastructure – Hands-on with AWS, GCP, or Azure; services like EC2/ECS/EKS, Lambda, RDS, S3; architecture for scalability and reliability. DevOps Culture – Familiarity with IaC (Terraform, CloudFormation) and configuration management; monitoring/observability tools. Performance Optimization – Experience with performance testing and optimization of code, queries, and front-end performance. Contributions & Leadership – Ability to lead projects; mentoring; open source contributions or portfolio projects. #J-18808-Ljbffr Straddle