Top Backend Engineer Jobs in Denver & Boulder, CO

Build and lead development of high-availability backend services for Affirm’s card loan platform. Design scalable APIs, data models, microservices, and event-driven systems supporting real-time loan attribution, approvals, origination, and refunds. Drive technical strategy, troubleshoot complex performance issues, collaborate with cross-functional teams, and mentor engineers while ensuring long-term system robustness and scalability.

Lead backend engineering strategy for Affirm’s search and recommendation platform. Design and launch highly available distributed systems, guide technical architecture and execution, improve team operations and reliability, establish engineering quality standards, collaborate with product, design, and analytics, and mentor engineers. The role focuses on search, recommendations, consumer shopping experiences, monetization, and scalable platform foundations.

Develop and scale backend streaming and data infrastructure using Kafka, Flink, AWS, Kubernetes, and related technologies. Break down projects, deliver tested software, collaborate with product and engineering teams, monitor system availability, participate in on-call support, debug code, conduct code reviews, and contribute to team development.

Architect, build, and operate large-scale relational and distributed SQL database infrastructure. Responsibilities include database control-plane automation, provisioning, failover, backups, upgrades, zero-downtime migrations, Kubernetes networking, connection proxy optimization, reliability monitoring, capacity planning, and operational support. The role also leads technical delivery, mentors engineers, establishes quality standards, collaborates cross-functionally, and contributes to team roadmap and on-call operations.

Build and operate production-grade Python backend services, APIs, distributed systems, data pipelines, and agentic workflows for an AI observability platform. Own ambiguous projects from prototyping through architecture, testing, deployment, and ongoing operation. Collaborate with product, machine learning, and infrastructure teams, while contributing React front ends when needed. The role requires strong backend depth, distributed-systems expertise, cloud experience, and end-to-end product ownership.

Own and evolve a high-traffic catalog API for satellite imagery. Design backend services and data pipelines in Python, optimize PostgreSQL performance over large geospatial datasets, operate cloud infrastructure, and deliver reliable deployments with automated testing. The role offers significant architectural ownership on a small, autonomous team and involves geospatial standards, scalable services, and production modernization.

Lead backend engineering strategy for Affirm’s international Identity team. Design and launch highly available distributed systems supporting KYC, user lifecycle management, and identity decisioning. Drive technical planning, cross-functional collaboration, operational excellence, monitoring, testing, and on-call readiness. Establish engineering quality standards, influence architecture, mentor team members, and deliver scalable systems using Python or Kotlin, AWS, MySQL, Spark, and Kubernetes.

Lead technical strategy and execution for foundational Trust and Safety systems supporting consumer risk and credit reporting. Design and operate highly available backend systems, improve reliability and monitoring, establish engineering standards, guide complex cross-functional initiatives, and mentor engineers. The role involves ownership of system architecture, technical planning, operational readiness, code quality, and team development.

Build and launch backend identity decisioning systems that validate consumer identity and satisfy KYC regulations. Collaborate with Product, Compliance, Auth, Fraud, Analytics, and engineering teams; decompose projects, write tested and extensible code, monitor system metrics, support availability and on-call operations, debug code, participate in reviews, and contribute to technical decisions and team development.

Build scalable backend services and infrastructure for mobile and web products. Design secure RESTful APIs, architect high-performance systems, apply engineering best practices, estimate and track Agile tasks, mentor teammates, collaborate with clients and engineers, and take ownership of technical solutions.

Design, build, and improve scalable backend systems that collect hard-to-access OSINT; build pipelines and ETL for messy data; collaborate with product and mission teams; mentor engineers and ensure reliable data delivery for DoD workflows.

Lead the technical direction and architecture of the Foundations platform team, owning authentication, authorization, SSO, secrets management, tenancy, and core platform services. Design APIs, drive services through launch, make technical decisions, establish engineering standards, and mentor engineers without formal management authority. Partner with engineering and product leaders to align execution with priorities.

Build reusable backend platforms and developer-facing tooling for performance testing, analysis, reporting, and AI-assisted engineering workflows. Enable service teams to independently incorporate performance testing into development and CI workflows through self-service capabilities, documentation, templates, diagnostics, and guidance. Partner with engineering teams, influence adoption, generalize solutions, and provide expertise on complex performance challenges.

Design and implement backend services, modernize legacy systems into microservices, ensure strong testing and production observability, and collaborate with Product and Engineering teams. The role requires independent project ownership, strong system design, AI-assisted development using tools such as Claude or Cursor, effective communication with nontechnical stakeholders, and adaptability in an ambiguous, fast-changing environment.

Leads cross-team backend initiatives and technical architecture for GitLab’s Core DevOps platform. Responsibilities include modernizing a monolith, establishing service, API, data, security, testing, and observability standards, guiding Go and Kubernetes practices, supporting Rust adoption, participating in incident response, mentoring engineers, reducing technical debt, and advancing AI-assisted engineering workflows.

Design, implement, and maintain scalable, secure, high-performance backend systems and public-facing APIs. Collaborate with Product and Data Science teams, lead initiatives improving efficiency and system performance, and support customer satisfaction. Work may involve distributed systems, pricing engines, identity management, authentication, authorization, API versioning, deprecation, and rate limiting.

Designs, builds, and scales backend services and integrations for payments, billing, identity, and partner connectivity. Sets technical vision and architecture for distributed systems, leads cross-team delivery, manages production rollouts, builds fault-tolerant services and data pipelines, and mentors engineers. The role partners with product, design, and engineering teams to deliver frequent, reliable improvements for Flex’s rent payment platform.

Design, build, and scale backend services and integrations for payment, billing, identity, and partner systems. Own API scoping, design, implementation, deployment, and production operations with minimal oversight. Build fault-tolerant systems, data pipelines, and scalable architectures while collaborating with product, design, engineering, and external partners. Contribute to reliability monitoring, observability, automation, technical standards, and mentoring in a distributed team.

Build and scale backend data platforms and services for real-time loan origination and financial reporting. Lead quarterly delivery, guide engineers, define technical plans, collaborate with product and design partners, improve reliability and operational practices, monitor service metrics, participate in on-call support, uphold engineering quality standards, and mentor team members. The role requires developing highly available distributed systems and scalable data pipelines using technologies such as Python, Kotlin, AWS, MySQL, Kubernetes, Spark, and Airflow.

Build and operate Go-based automation for PostgreSQL provisioning, configuration, upgrades, failover, scaling, and decommissioning at GitLab.com scale. Develop a PostgreSQL-as-a-service platform, integrate cloud infrastructure and infrastructure-as-code tooling, improve database performance and reliability, and create safe upgrade automation. The role includes production ownership, architecture leadership, code reviews, documentation, cross-team collaboration, mentorship, and using AI agents in engineering workflows.

Design, develop, launch, and maintain scalable backend systems and APIs used by merchant and partner integrations. Collaborate with engineers and stakeholders, balance speed with system quality, debug code, conduct code reviews, and write tested, extensible software. The role requires experience with distributed systems, Python or Kotlin, AWS, MySQL, and Kubernetes, along with strong communication and ownership of professional growth.

Design, build, and optimize scalable backend services, APIs, and data pipelines. Integrate with third-party billing/commerce systems, maintain serverless/event-driven architectures on AWS, ensure security and performance, implement automated tests and CI/CD, mentor engineers, and drive architectural decisions.

Build and scale backend systems for a high-traffic donor CRM and payments platform. Own performant SQL and realtime querying, optimize payment flows, implement AI agents, and collaborate across product and design to ship resilient, production-grade features at scale.

Design, build, and maintain backend services and APIs using Ruby on Rails. Improve performance, scalability, reliability, and write well-tested production code. Collaborate with Product, Frontend, Data Engineering, and QA teams.

Design, build, test, and support EPIC integration solutions across the full interface lifecycle. Gather requirements, resolve integration issues, develop standards and documentation, and provide production support within a remote, volunteer, part-time setup.