Top Senior Backend Engineer Jobs in Denver & Boulder, CO

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, 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 and implement scalable backend services for payment and transaction workflows using Java. Own end-to-end features from data model and APIs to Angular frontends, improve reliability and performance, refactor legacy systems, troubleshoot production issues, and collaborate with product and design. Leverage AI-assisted development tools responsibly and share best practices across the team.

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.

Design and deliver LLM-powered, agentic AI systems to automate customer support and compliance. Build scalable, secure backend infrastructure in Python and Go, integrate third-party models/APIs, implement grounding and guardrails, and measure performance. Lead end-to-end projects, mentor engineers, conduct code reviews, and participate in on-call and incident response to improve resolution times and reduce operational costs.

Build and optimize high-performance backend systems for an xOT security platform using Rust. Participate across development lifecycle, design scalable microservices, integrate third-party devices and data providers, incorporate AI tools, and improve observability and reliability through testing, debugging, and peer review.

Lead backend and full-stack work on the Payments team, building multi-gateway integrations (Stripe, PayPal), payment APIs, and customer payment UIs. Ensure secure, compliant (PCI-DSS) payment flows, reliability, observability, and scalability across AWS/Kubernetes microservices. Partner cross-functionally to design architecture, implement settlement/reconciliation, and maintain high availability.

Design, implement, and evolve complex backend features and architecture. Improve reliability, performance, and security at scale. Mentor engineers, participate in incident response, set backend standards, and integrate agentic AI into production workflows.

Design and implement backend and real-time features in the GitLab monolith for portfolio planning at scale. Optimize PostgreSQL performance, evolve APIs (GraphQL/REST), build capacity planning and work-item hierarchies, create proofs of concept, maintain automated tests, support safe rollouts with feature flags and observability, mentor contributors, and participate in on-call and production troubleshooting.

Design, develop, and maintain scalable, high-performance backend and middleware services on the JVM using Java and Spring/Spring Cloud. Build and enhance microservices, work with AWS and Docker, implement SQL/noSQL solutions (MySQL, Elasticsearch), use Git-based source control and JIRA, collaborate across engineering, design, and QA, and mentor teammates while following best practices and Agile methodologies.

Design and build scalable backend systems, data pipelines, and cloud infrastructure. Own CI/CD, containerization, databases, and reliability; collaborate with tech leads to deliver secure, production-grade solutions for startups in a fully remote environment.

As a Senior Software Engineer, you'll own backend systems, mentor team members, and collaborate with product and design to build user-focused solutions.

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 and scale platform infrastructure, backend services, developer tooling, CI/CD pipelines, and secure cloud-native systems. Improve developer experience, reliability, observability, and incident response while establishing security and compliance controls. Partner with engineering and product leaders to shape architecture and platform strategy, mentor engineers, and support customer-facing logistics projects. The role uses Python, AWS, Terraform, containers, orchestration, event-driven architectures, and relational databases.

Senior backend engineer responsible for designing and implementing new features, scaling and optimizing the platform, improving Postgres and Elasticsearch performance, fine-tuning LLMs, and making architectural decisions. Collaborate with engineering team, take ownership of features, write performant, maintainable code, and help shape product and infrastructure for data-intensive applications (NLP, search, indexing).

Build reliable AI-powered, agentic backend systems to remove friction across the software development lifecycle. Design multi-step orchestration, safety checks, and evaluation tooling; apply distributed-systems judgment; work across GitLab codebases and with a distributed team to productionize solutions that may become customer-facing.

Audit backend services, APIs, databases, queues, and data flows for scalability and reliability issues. Identify bottlenecks, document findings, and implement production fixes including code refactoring, schema redesign, caching, indexing, query optimization, and service restructuring. Partner with engineers through pairing, reviews, and handoffs. Conduct performance and load testing while improving system latency, resilience, and infrastructure efficiency.