Top Senior Backend Engineer Jobs in Denver & Boulder, CO

Own and deliver goals for ML training and serving infrastructure. Lead engineers through ambiguous, distributed-systems challenges; design, develop, and operate highly available backend platforms; monitor reliability and support on-call operations. Collaborate with product and engineering stakeholders, improve code and design standards, identify and resolve technical issues, and mentor team members. The role focuses on scalable systems that enable production model training and serving.

Own and deliver quarterly engineering goals for Affirm’s ML Feature Platform. Design, develop, and launch scalable backend systems, lead engineers through ambiguous problems, collaborate with product and design stakeholders, improve platform reliability and availability, support on-call operations, establish quality standards, and mentor team members. The role focuses on highly available distributed systems supporting machine learning feature creation, storage, serving, and offline backfilling.

Design, develop, test, deploy, and monitor scalable backend systems for a payroll SaaS product. Build APIs and microservices, collaborate with product and engineering teams, participate in code reviews, and own the full development lifecycle in a continuous delivery environment. The role emphasizes Kotlin, Scala, or Java, cloud platforms, automated testing, relational databases, scalable architecture, and responsible use of AI coding tools.

Own backend engineering goals for Consumer Engineering, lead delivery of scalable systems, collaborate with product, design, and analytics, improve reliability and code quality, resolve technical and business issues, support on-call operations, and mentor engineers.

Own quarterly engineering goals, lead backend engineers through ambiguous problems, collaborate with product and analytics partners, improve system reliability and availability, monitor operational metrics, establish quality standards, and mentor team members. The role requires designing and launching highly available distributed backend systems at scale using Python or Kotlin, AWS, MySQL, and Kubernetes, while driving technical planning and safe changes across large codebases.

Design and evolve high-scale backend capabilities for GitLab’s container registry. Drive architecture, performance, reliability, security, APIs, testing, and operational readiness. Mentor engineers, influence technical direction, participate in incident response, and collaborate asynchronously across product, infrastructure, data, frontend, and security teams. Integrate and evaluate agentic AI systems in production engineering workflows while promoting responsible and effective use.

Architect and operate Affirm’s large-scale Amazon EKS compute platform, including cluster lifecycle, node management, autoscaling, shared components, infrastructure automation, workload safety policies, observability, cost and capacity optimization, and self-service workflows. The role drives technical strategy, mentors engineers, partners cross-functionally, and participates in on-call incident response.

Build and operate Affirm’s AI platform, including LLM and MCP gateways, agent runtimes, evaluation services, and governance controls. Design highly available backend systems, manage identity, quotas, routing, caching, reliability, observability, and security for AI workloads. Own projects from design through launch and on-call, establish engineering standards, collaborate across teams, mentor engineers, and help scale AI systems into production.

Build and enforce workload safety standards across Affirm’s Amazon EKS fleet. Responsibilities include Kubernetes resource management, workload isolation, disruption handling, cluster capacity analysis, policy automation, production debugging, incident response, fleet-wide rollouts, technical leadership, mentoring, and measuring infrastructure impacts on availability, latency, risk, and cost.

Build and ship backend features end-to-end using Ruby on Rails and SQL. Lead complex technical projects, solve architecture challenges, establish standards, conduct meaningful code reviews, resolve high-risk bugs, document systems, collaborate across engineering teams, and mentor junior engineers.

Build and release server-side product features and language-model-powered agents. Define system architecture, data structures, and service interfaces while owning projects from problem definition through production. Partner with founders on product direction, customer requirements, and deployments. The role requires independent judgment, advanced Python expertise, SQL database experience, and practical experience developing language-model or autonomous-agent software.

Design, develop, and maintain scalable PHP/Laravel backend applications and RESTful APIs. Build third-party integrations, optimize PostgreSQL databases, write automated tests, and manage Docker-based deployments across AWS environments. Monitor application health, troubleshoot defects, participate in code reviews, and improve CI/CD pipelines, documentation, and engineering processes while collaborating with product, QA, frontend, and DevOps teams.

Build and operate the backend platform powering autonomous cybersecurity agents across multi-tenant customer environments. Responsibilities include durable agent runtimes, tool and connector frameworks, safe-change pipelines, tenant isolation, ETL and GraphQL services, observability, auditability, and distributed systems reliability. Partner with AI researchers and security teams to productionize agent capabilities while managing authorization, credentialing, rollback, tracing, and data processing.

Build backend growth experiments for Clubhouse across invites, notifications, onboarding, reactivation, ranking, and personalization. Improve backend scalability and maintainability while working in a mature codebase. Partner with product, design, engineering, and data science teams to instrument experiments, analyze results, establish guardrails, and iterate quickly on features serving millions of users.

Own the end-to-end design, delivery, operation, and improvement of high-traffic Python backend services powering search, autocomplete, browse, recommendations, and public configuration APIs. Responsibilities include API evolution, distributed systems architecture, performance and reliability improvements, observability, incident response, code review, mentoring, and cross-functional collaboration. The role involves on-call ownership, scalable service design, backward compatibility, and leading small engineering initiatives.

Design and implement Mojo compiler features, optimization passes, and code generation for CPUs, GPUs, and AI accelerators using MLIR and LLVM. Collaborate with kernel authors, hardware engineers, researchers, and open-source contributors to improve compiler performance, language design, developer experience, and the broader Mojo technology stack.

Design, build, and maintain backend systems for payments, subscriptions, billing, and revenue workflows. Develop APIs, integrations, event-driven processing, database models, reconciliation tools, access controls, testing, monitoring, and reliability safeguards. Own complex initiatives from architecture through production, investigate incidents, collaborate with finance and product teams, and provide technical guidance while using AI-assisted development tools responsibly.

Lead technical vision and strategy for Affirm’s Cards backend engineering organization. Architect scalable and reliable platforms, guide cross-team initiatives, champion AI adoption and engineering excellence, influence technical roadmaps, and mentor engineers through Staff level. The role requires strong architectural expertise, organizational leadership, project management, communication, and cross-functional collaboration.

Own and deliver backend lakehouse infrastructure goals, lead engineers through complex problems, and build highly available distributed data systems. Collaborate with product, design, analytics, and engineering stakeholders; define scalable technical solutions; improve code quality and engineering standards; monitor operational health; support on-call responsibilities; and mentor team members.

Own backend features from inception through production, develop and improve Kotlin services, write maintainable and well-tested code, and design scalable, reliable distributed systems within a small cross-functional team.

Designs and scales high-performance backend web services and ETL pipelines supporting tens of thousands of transactions per second. Responsibilities include architecting fault-tolerant distributed systems, improving performance, developing monitoring and deployment strategies, collaborating across product and engineering teams, and supporting recruiting and onboarding. The role requires expertise in data-intensive systems, microservices, cloud architectures, and commercial SaaS products.

Own backend services for a card program, including authorization, clearing, refunds, disputes, and decline handling. Investigate transaction issues, collaborate with issuing partners, make product decisions, and measure outcomes. Improve infrastructure, CI/CD, observability, and monitoring while using AI tools to accelerate coding, analysis, investigation, and operational automation.

Lead development of scalable backend services and data platforms using Scala and Rust. Design distributed systems, APIs, data pipelines, and security-data workflows; guide Scala-to-Rust migration; support Python-based malware analysis, threat detection, and machine learning systems. Own production reliability, architecture, code quality, reviews, deployment, observability, and incident response in a cloud-native environment.

Develop and improve core software services supporting customer intake, application screening, and information dissemination. Design distributed, microservice-based systems; identify bottlenecks; improve reliability, scalability, and business logic; and contribute to modernization and architectural decisions. Work independently across the stack, communicate technical trade-offs, mentor junior developers, and use AI and automation tools to improve engineering outcomes.

Design and scale asynchronous Python backend systems, including REST/WebSocket APIs, multi-agent LLM workflows, provider-agnostic integrations, and RAG pipelines. Own relational data models, observability, performance, CI/CD, and production deployment. Establish AI governance covering code review, provenance, licensing, security, compliance, and customer data handling. Drive ideas from concept through production while owning architecture and outcomes.