Top Principal Software Engineer Jobs in Denver & Boulder, CO

As a Senior Principal Engineer, you'll define and drive the technical strategy for customer experience platforms, lead architectural decisions, and mentor engineering teams to enhance customer and agent experiences.

Design, build, deploy, and maintain resilient, scalable production systems for Toast’s retail customers. The role sets long-term technical architecture and strategy, communicates technical direction, mentors senior engineers, improves engineering productivity, diagnoses performance issues, and drives initiatives amid ambiguity. Engineers collaborate directly with retail customers, visit stores, understand operational workflows, and use AI tools to improve development velocity and quality.

Lead architecture and technical execution for Toast’s Payroll and Team Management products. Own authentication, authorization, and organizational hierarchy across a multi-tenant SaaS platform. Drive high-scale, full-stack initiatives, modern agentic development practices, integrations, technical strategy, quality standards, deployment practices, and cross-functional collaboration. Mentor engineers across teams and leverage AI tools and LLM integration to improve software development velocity and quality.

Build and maintain a TypeScript/JavaScript SDK for IP video playback across web, smart TVs, and set-top boxes. Design clean APIs, implement video playback components (MSE/EME/DRM), optimize reliability and performance, collaborate with cross-functional teams, and support operations to ensure high-quality streaming for millions of users.

Lead architecture, design, and delivery of PET product features; write production full‑stack code; champion testing, observability, CI/CD and operational readiness; mentor engineers and collaborate with product to shape technical roadmap.

This role involves leading technical projects across multiple teams, designing scalable systems, collaborating with cross-functional teams, and mentoring engineers, focusing on payroll and tax systems at Gusto.

Design, architect, develop, test, and oversee complex software systems for space technologies. Lead engineering teams, make high-level technical decisions, guide large-scale projects, troubleshoot distributed systems, and drive software strategy. Collaborate with technical and non-technical stakeholders, conduct code reviews, document systems, mentor engineers, and evaluate technologies, methodologies, automation, cloud platforms, databases, and secure development practices for classified environments.

Lead design, build, deployment, and operation of highly resilient, high-throughput configuration and publishing systems. Define long-term architecture and strategy, mentor senior engineers, diagnose and fix performance bottlenecks, and leverage AI tools to improve engineering productivity and platform capabilities.

Develop and maintain embedded satellite software, including command and control, mission planning, data analysis, and test infrastructure. Perform full software lifecycle activities from requirements and architecture through coding, testing, integration, documentation, and support. The role requires collaboration across teams, formal development practices, object-oriented design, UML modeling, and experience with cloud, web, database, and high-level programming technologies. Work is on-site five days per week and requires an active TS/SCI clearance.

Develop and support embedded satellite software, including command and control, mission planning, data analysis, and test infrastructure. Perform the full software lifecycle from requirements and architecture through coding, testing, integration, documentation, and support. Work with technologies including C/C++, Rust, Python, Ruby, cloud platforms, containers, web services, databases, and DevSecOps practices. The role is on-site five days per week and requires an active TS/SCI clearance.

Develops embedded satellite command-and-control, mission planning, data analysis, and test infrastructure software. Performs full software lifecycle activities, including requirements, architecture, design, coding, testing, integration, documentation, and support. The role requires software development across cloud, web, frontend, backend, modeling, and scheduling technologies, along with formal engineering practices, UML, object-oriented design, and active TS/SCI clearance. Work is primarily onsite five days per week.

Develops embedded satellite command and control, mission planning, and data analysis software and test infrastructure. Performs full software lifecycle activities, including requirements, architecture, design, coding, testing, integration, documentation, and support. The role requires expertise in modern software technologies, cloud and web development, object-oriented design, UML, configuration management, and formal development practices. It is fully on-site and supports defense and space missions.

Develop satellite command and control, mission planning, data analysis, and embedded software systems. Perform full software lifecycle activities including requirements, architecture, design, coding, testing, integration, documentation, and support. Contribute to CI/CD, cloud, containerized, web, database, modeling, simulation, and test infrastructure development while collaborating across engineering and business teams. This is an on-site role requiring an active TS/SCI clearance.

Develops embedded satellite command-and-control, mission planning, data analysis, and test infrastructure software. Performs full software lifecycle activities, including requirements, architecture, design, coding, testing, integration, documentation, and support. The role requires expertise in software development, cloud and web technologies, object-oriented design, UML, configuration management, and formal development practices. Work is onsite five days per week in office, laboratory, production, or cleanroom environments, with possible travel between company and other locations.

Provides hands-on technical leadership for Pantheon’s P1 zero-to-one product and company-wide engineering strategy. Owns architecture across real-time collaboration, APIs, data, publishing, integrations, and developer experience; establishes reliability, security, observability, and delivery standards; guides build-versus-buy decisions; mentors senior engineers; partners with product, design, security, infrastructure, and customers; and contributes code to validate architecture and unblock critical initiatives.

Lead architecture and roadmap for Azure PostgreSQL systems; design and review scalable, maintainable database engine features (query processing, storage, transaction logging, recovery, versioning, IO, scale-out). Influence coding standards and run code reviews, write proof-of-concept or production code, contribute to open-source PostgreSQL/Linux, and participate in rotational on-call operations.

Lead the architecture, technical strategy, and roadmap for Microsoft's Windows ML compiler stack. Design high-performance compiler infrastructure, execution engines, optimization frameworks, and developer tools supporting CPU, GPU, and NPU workloads. Drive NPU enablement, graph optimization, scheduling, memory management, code generation, and hardware abstraction. Partner with silicon vendors and internal teams, influence AI hardware and platform strategy, lead cross-team initiatives, and mentor engineers developing on-device and generative AI capabilities.

Principal Software Engineer responsible for designing, developing, testing, and delivering software across multiple mission-critical projects. The role includes cloud-native application development, API and microservices architecture, DevSecOps pipelines, secure coding, code reviews, technical standards, architectural proofs of concept, and collaboration with software, data, and DevSecOps engineers. Government and defense project experience is required.

Lead long-term technical strategy and execution across multiple teams, architecting and evolving foundational frontend/backend systems and platforms at massive scale. Drive AI/ML adoption, solve ambiguous, high-impact problems, remain hands-on in critical system design and implementation, and align senior leaders on roadmaps and engineering standards.

Lead legacy application assessments and modernization strategy for U.S. Air Force systems. Own architectural decisions, technical direction, and test strategy while collaborating with government engineers, vendors, product managers, researchers, and designers. Promote secure, compliant, agile engineering practices; coach government teams; evaluate technical environments; communicate recommendations; and demonstrate modern AI-assisted development practices. The role is fully remote, requires U.S. citizenship and CAC eligibility, and involves occasional quarterly travel to Air Force bases.

Lead end-to-end design and delivery of AI-infused, enterprise full-stack applications on Azure. Architect resilient solutions, build Copilot/agentic features, enforce engineering best practices, mentor engineers, collaborate with PM/UX teams, ensure quality/reliability, and support production services and integrations.

Design and implement PostgreSQL internals, indexing, query engine extensions, and storage-layer features to support large-scale document workloads on Azure. Profile distributed systems, tune performance, collaborate with open-source communities, conduct design/code reviews, and drive cross-team alignment for mission-critical database features.

Leads the technical vision, architecture, and execution of AI performance, framework, benchmarking, and developer-productivity initiatives. Drives cross-team architecture, resolves complex systems trade-offs, mentors technical leaders, and contributes hands-on through prototyping, implementation, reviews, debugging, observability, and automation. Delivers measurable improvements in model onboarding speed, runtime performance, reliability, hardware utilization, and Azure capacity efficiency across models, frameworks, compilers, runtimes, systems, services, and hardware.

Lead design and implementation of embedded OS layer software and platform infrastructure. Develop Yocto-based embedded Linux distributions, BSPs, hypervisors, device drivers, CI/CD pipelines, and security features (secure boot, OTA). Act as platform point of contact, collaborate with product teams, and produce engineering policies and documentation.

Designs and implements embedded satellite command-and-control, mission planning, and data analysis software. Performs full software lifecycle activities (requirements, architecture, design, coding, testing, integration, documentation, support) and maintains on-site engagement. Works across programs using CI/CD, containerization, cloud, and modern web/back-end/front-end technologies.