Top Senior 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.

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.

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.

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.

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.

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.

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.

Build and own the graph layer and RAG architecture enabling agent reasoning over full patient context. Select graph DBs, design query patterns, and ensure temporal coherence. Implement event-driven Kafka pipelines for auditable, immutable agent workflows and enforce ReBAC permissions. Prioritize safety and scalable AI-assisted workflows, participate in spec and plan reviews, and drive architecture decisions.

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.

Develop and evolve a high-throughput, low-latency US sports betting platform using distributed systems and microservices. Build resilient, scalable services for peak sporting events, collaborate with technical and non-technical stakeholders, contribute to architectural direction, and mentor junior engineers. The role also involves cloud infrastructure, Kubernetes, reliability, concurrency, debugging, and delivery of quality software in an agile environment.

Design and scale backend infrastructure for conversational AI, including databases, query and retrieval systems, distributed services, and real-time voice-agent orchestration. Own TypeScript/Node.js and Python services using cloud-native technologies, improve observability and reliability, and scale simulation infrastructure to over 200,000 concurrent calls. Diagnose performance bottlenecks, maintain high availability, and rapidly ship production solutions in a startup environment.

Build and maintain scalable Java backend services and APIs on AWS. Responsibilities include designing concurrent systems, debugging complex issues, optimizing performance, translating business requirements into technical solutions, collaborating cross-functionally, and owning projects in a fast-paced startup environment.

Leads backend engineering for a payments platform by designing scalable Golang microservices and RESTful APIs, driving architecture, improving reliability and observability, and supporting production systems. Collaborates across product and engineering teams, participates in on-call operations, establishes SLOs and incident processes, manages technical debt, and mentors junior engineers.

Design, develop, and maintain scalable backend architectures supporting Cresta’s AI Agent solutions. Lead initiatives improving reliability, performance, availability, security, and cost efficiency in high-volume production systems. Collaborate with frontend and machine learning engineers, optimize APIs, databases, server response times, and data processing, and deploy containerized microservices across cloud environments.

Lead architecture and hands-on development of scalable backend systems and APIs supporting real-time applications at massive scale. Own the full engineering lifecycle, establish standards for reliability and testing, troubleshoot production issues, influence technical roadmaps, collaborate cross-functionally, and mentor engineers. The role requires deep backend development, distributed cloud systems, system design, automated testing, and technical leadership experience.

Design and build scalable backend services and APIs using Java on AWS. Write clean, maintainable code; debug performance bottlenecks; develop concurrent software for multi-core systems; and collaborate with frontend, design, and product teams to solve large-scale technical problems. The role requires balancing technical rigor with rapid delivery in a small, fast-paced startup environment.

Design, build, and operate backend services for Bestow’s insurance platform using Python, Go, Java, and PostgreSQL. Collaborate on technical decisions, integrations, carrier onboarding, and scalable platform capabilities. Mentor engineers through reviews and pairing, improve production reliability and observability, participate in on-call support, and communicate technical decisions in a remote-first environment. Use agentic AI coding tools daily and help establish effective AI-assisted development practices.

Design, develop, and maintain scalable backend services, REST APIs, server-side applications, and database systems. Improve performance, reliability, monitoring, and security; integrate third-party services; write tested code; troubleshoot production issues; and contribute to code reviews and engineering best practices. Collaborate with frontend, DevOps, QA, and product teams while deploying and operating applications using cloud infrastructure, Docker, and CI/CD pipelines.

Design, build, and maintain scalable backend services, REST APIs, server-side applications, and database systems. Improve performance, reliability, security, monitoring, and logging; integrate external services; write tested code; review implementations; troubleshoot production issues; and collaborate with frontend, DevOps, QA, and product teams. The role also involves Docker, CI/CD, cloud deployments, and potentially Kubernetes, infrastructure as code, and event-driven systems.

Build and operate Python backend services, REST APIs, clinical data models, and batch or event-driven pipelines. Work with FHIR and HL7 healthcare data to support reliable integrations, reporting, analytics, and AI workflows. Establish data quality, validation, governance, lineage, monitoring, and auditability practices. Lead architectural discussions, review implementations, mentor engineers, and collaborate with clinical, product, analytics, and AI teams.