Top Senior Full-Stack Engineer Jobs in Denver & Boulder, CO

Build scalable, data-intensive products from the ground up, focusing on Java/Kotlin backend services, REST or GraphQL APIs, data access, and React/TypeScript interfaces. Responsibilities include architecture, performance optimization, testing, observability, production troubleshooting, technical documentation, and end-to-end feature ownership. Collaborate with data, reporting, design, and product teams while using AI-assisted development tools to accelerate delivery.

Develop fullstack web applications, enhance platform performance, collaborate on high-impact opportunities, and ensure stable, scalable solutions. Engage in rapid iterations and be a committed team player.

Leads technical vision and strategy for Affirm’s Marketplace, Search, Ads Platform, and consumer experiences. Designs scalable full-stack platforms, guides architecture and technical excellence, coordinates initiatives across engineering teams, mentors engineers, and drives reliable delivery of customer-focused products across iOS, Android, and Web.

Own the specification, design, and implementation of features for FareHarbor’s large-scale web application. Collaborate with product team members, develop scalable and performant full-stack solutions, improve automated testing, resolve technical challenges, and participate in code reviews. The role requires strong Python and JavaScript skills, experience with front-end and back-end frameworks, relational databases, performance optimization, and agile development.

Own end-to-end full-stack feature development across React/TypeScript interfaces and Elixir backend services for spacecraft modeling, simulation, and ground-control software. Drive architecture, technical debt reduction, performance, reliability, testing, API design, and production deployment. Mentor engineers, establish coding standards, collaborate with product, design, QA, operators, and astrodynamics teams, and deliver complex data-dense, real-time applications.

Develop and optimize high-scale Adobe Commerce ecommerce platforms using PHP, JavaScript, Node.js, GraphQL, REST, and MySQL. Separate business logic from presentation layers, improve database and caching performance, build CI/CD validation, monitor production systems with New Relic, and create endurance load tests. Integrate identity, payment, and tax systems while mentoring junior engineers and leading offshore teams.

Lead technical direction and delivery for the Acquisition & Onboarding full‑stack team. Build and maintain mobile (React Native/native) and web experiences, backend services at scale, and operational tooling. Drive architecture, mentor engineers, ensure reliability/monitoring/on‑call readiness, collaborate with product and design, and improve dev processes, testing, and release practices to impact conversion and retention.

Owner of Vannevar's authentication and authorization platform: build tenant-isolated auth systems, self-service user/group/permission admin UI, tooling to visualize and validate access, feature-flag and platform management interfaces, and shared authorization capabilities across products.

Senior fullstack engineer to build and scale Brigit's consumer finance platform. Own end-to-end features across frontend (React/React Native/TypeScript) and backend (Java/REST/SQL), optimize database and APIs for high scale, integrate 3rd-party services, implement risk and transaction algorithms, improve CI/CD, testing, monitoring, and internal tooling to support millions of users.

As a Senior Software Engineer, you will design and build a cutting-edge identity search platform and implement AI systems for defense applications, working closely with cross-functional teams to enhance user workflows and support national security.

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.

Responsible for leading a team of engineers, supporting product development, identifying technical issues, and ensuring high-quality code delivery in backend systems at scale.

Lead design and implementation of the PSA Liquidity Platform connecting buyers and sellers. Build buyer tooling, matching/ranking engines, and seller experiences. Architect and operate microservices and Kafka-driven systems on Kubernetes/AWS, instrument observability, apply AI tooling across the SDLC, and drive cross-functional delivery from 0-to-1 while owning end-to-end outcomes.

Build and own CRM features and workflow automations supporting sales, marketing, onboarding, and support. Develop full-stack functionality using Next.js, FastAPI, Inngest, and related technologies; partner with teams to automate workflows; create agentic solutions for enrichment and task automation; and manage features from planning through monitoring and refinement. The role requires strong web development expertise, product sense, autonomy, communication, and experience with modern JavaScript or TypeScript frameworks and orchestration tools.

Own full-stack features for Techstars OS from data ingestion and APIs through React interfaces and production delivery. Build AI-native search, retrieval, and assistive workflows using founder and portfolio data. Lead migration and retirement of legacy tools, develop data pipelines, improve testing and CI/CD, and provide architectural guidance. The role requires strong autonomy, written communication, and end-to-end ownership across cloud infrastructure and product development.

Lead a four-week project to launch a production inventory table and artifact-detail experience for an AI security platform. Build frontend-heavy, data-dense workflows with large tables, filtering, paging, and resilient state management. Contribute across TypeScript, React, Next.js, Node.js, Postgres, REST APIs, and background jobs. Partner with technical and design leadership, review code, and potentially develop deduplication, reporting, and knowledge-graph features.

Build and ship end-to-end product features across an author analytics dashboard, marketing site, free tools, billing, email, and AI-assisted functionality. Design data models and APIs, integrate third-party services, develop production LLM features, and maintain testing, monitoring, performance, and observability. The role includes code review, technical documentation, independent product decisions, and close collaboration with the founder in a remote-first environment.

The Senior Full-Stack Engineer will manage client relationships, design integration solutions, and ensure seamless delivery and optimization of technical workflows, while leveraging AI for efficiency.

Build and ship full-stack features for customer-facing Console and Playground, plus internal tools. Design and maintain APIs and backend services, implement accessible performant frontends, translate product requirements into incremental work, and improve code quality through reviews and design discussions.

Designs accessible, responsive user interfaces and develops scalable cloud-native full-stack applications for mission-critical defense systems. Responsibilities include front-end and back-end development, API and microservices integration, cloud deployment, CI/CD automation, testing, performance optimization, architecture reviews, code reviews, troubleshooting, and mentoring junior developers. The role collaborates with software, data, cybersecurity, DevSecOps, and systems engineering teams in a fully onsite Colorado Springs environment.

Develop and maintain full-stack web interfaces, backend scoring services, databases, and automated agents for cyber range environments. Responsibilities include architecture, coding, unit and integration testing, system validation, documentation, requirements analysis, and integration with versioned cyber ranges. The role requires collaboration across complex hybrid and multi-vendor environments, with a focus on cyber training systems, infrastructure automation, networking, virtualization, and Agile software development.

Develop and maintain full-stack web interfaces, backend scoring services, databases, and automated scoring agents for cyber range environments. Responsibilities include architecture, coding, unit and integration testing, documentation, system integration, and collaboration with RangeOS developers. The role requires work across Linux, Windows, virtualization, networking, cloud, hybrid, and multi-vendor environments, with participation in requirements analysis, solution design, Agile development, and cyber training platform integration.

Build and evolve Humana’s NBA Action Library and Command Center using React, TypeScript, Node.js, PostgreSQL, and Kafka. Develop accessible front-end experiences, REST APIs, data models, integrations, automated tests, and reliable state-driven workflows. Collaborate with product, design, and platform teams to deliver secure, scalable software supporting action creation, governance, versioning, preview, and publishing.

Develop secure, scalable full-stack software for satellite ground communications and data transport. Responsibilities include building Python backend services and APIs on AWS, developing TypeScript and Vite front-end applications, designing microservices, managing PostgreSQL databases, implementing authentication and authorization, supporting containerized deployments, resolving production issues, refining requirements, collaborating with MBSE and test teams, and mentoring engineers.

Develop and expand Laravel/PHP backend and Vue.js frontend applications for Relocity’s global mobility platform. Responsibilities include architecture, implementation, testing, code reviews, debugging, documentation, REST API development, database optimization, and troubleshooting. The engineer will own complex technical problems, collaborate with Product and Design, apply product and user-experience thinking, and use AI-enabled development tools to accelerate software delivery.