Top Senior Backend Engineer Jobs in Denver & Boulder, CO

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.

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, 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.

Owns delivery of backend money movement and card ledger systems, leading engineers through complex problems and ambiguity. Collaborates with product, design, analytics, and engineering stakeholders; defines scalable technical solutions; supports system availability, monitoring, on-call operations, code quality, and engineering standards. The role also includes mentoring and developing team talent while building highly available distributed systems for Affirm’s financial products.

Leads architecture and hands-on development of scalable backend systems and APIs supporting real-time applications. Owns the engineering lifecycle, writes high-performance code, establishes testing and reliability practices, resolves production issues, guides technical roadmaps, collaborates cross-functionally, and mentors engineers. The role requires expertise in object-oriented backend development, distributed cloud systems, automated testing, system monitoring, and technical leadership.

Own and lead the technical direction of a major codebase section while designing, building, testing, documenting, and maintaining secure, scalable API-based decisioning products. Partner with product, engineering, and security teams on agile delivery, troubleshoot production issues, meet SLA requirements, and participate in an on-call rotation.

Build and scale Go backend services for agent quoting, configuration, and application submission. Partner with adjacent teams, resolve partner-specific edge cases, provide architectural leadership, write unit and integration tests, review code, and promote automation, CI/CD, and continuous improvement. The role expects daily use of AI coding tools and ownership of services across distributed systems and microservices environments.

Design, build, and operate backend Go services and smart contracts that mint, burn, bridge, and reconcile wrapped assets across multiple chains. Own end-to-end delivery from smart contract deployment through API design, SLOs, and production rollout. Drive asset migration pipeline improvements, run on-call operations, build observability and runbooks, and mentor junior engineers.

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.

Design, build, test, and maintain backend services and APIs powering the insurance platform. Integrate payments, documents, and data providers, improve system stability, performance, and scalability, mentor team members, and participate in architectural decisions and agile ceremonies.

As a Senior Backend Engineer at DuckDuckGo, you'll lead backend projects, mentor engineers, and develop AI-enhanced features for the company's privacy-centric product line.

Design and implement secure, scalable backend services for speech inference and audio processing. Optimize networking, transcoding, latency, memory, and distributed compute orchestration. Measure and improve system performance, debug complex networking/scheduling/HPC issues, customize services for customers, and partner with Product to deliver features end-to-end.

Design, build, and operate payment services for card processing, refunds, reconciliation, and processor integrations. Develop scalable Kotlin and Java Spring Boot APIs, optimize PostgreSQL schemas and SQL, and implement idempotency, retries, webhooks, audit trails, and reconciliation. Respond to payment incidents, conduct root cause analysis, collaborate cross-functionally, review architecture and code, and mentor engineers. The role requires strong distributed-systems, payments, PCI DSS, debugging, and production operations experience.

Build and operate scalable backend services for connected devices, including device connectivity, telemetry ingestion, health monitoring, command and control, and data pipelines. Collaborate with firmware, mobile, and product teams on APIs and workflows. Use AWS, microservices, streaming systems, observability tools, and AI coding agents to deliver reliable features, participate in incident response, and improve automation and engineering practices.

Designs, builds, and supports scalable Java and Spring Boot microservices on GCP. Responsibilities include SQL and data pipeline development, CI/CD with Jenkins, infrastructure automation using Terraform, comprehensive JUnit testing, code reviews, agile tracking, production incident resolution, and root-cause analysis. The role collaborates with product, architecture, and cloud engineering teams while mentoring peers and improving engineering standards. Remote work is available, with less than 10% travel and a requirement to obtain and maintain Public Trust.

Lead the architecture and implementation of scalable conversational AI systems and backend services. Own projects from ideation through execution, shape the engineering roadmap, design RESTful APIs and business logic, integrate external partners, evaluate ML-driven results, and optimize platform scalability. The role also includes technical leadership, mentoring, code reviews, cross-functional collaboration, and product-focused decision-making.

Design, build, maintain, and improve backend services and APIs supporting real-time translation. Own complex features from technical design through delivery, work with distributed systems, messaging, event streaming, caches, and NoSQL stores, and resolve production issues. Write comprehensive tests, participate in design and code reviews, improve reliability and maintainability, collaborate cross-functionally, and use AI-assisted development tools responsibly.

Build end-to-end product features with a backend focus: schema and API design, UI work in React/TypeScript, GCP/Terraform infrastructure, CI/CD, DB performance tuning, production ownership, and product decision-making using AI coding tools.

Lead and deliver quarterly goals for a backend team; guide engineers through ambiguous problems; collaborate with product, design, and analytics; identify and resolve project and technical issues; ensure operational availability and on-call readiness; set code and design quality standards; and mentor and develop team members.

Own and scale production backend systems using Ruby on Rails, PostgreSQL, Sidekiq, APIs, microservices, queues, and distributed architectures. Diagnose and improve reliability, security, performance, observability, testing, and deployment practices. Integrate third-party services, collaborate with product, data, design, and frontend teams, and modernize inherited systems while maintaining delivery speed. The role requires strong production ownership, pragmatic technical judgment, and comfort working remotely in a fast-moving startup.