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

Develop and deploy customer-focused web, mobile, and backend applications across the full software stack. Design major features, contribute to architecture decisions, conduct code reviews, and ensure secure, high-quality implementations. Collaborate with stakeholders and cross-functional teams using Agile and SDLC practices. Manage version control, CI/CD, environments, and releases; maintain automated test coverage and perform root-cause analysis. Build and optimize relational data solutions using SQL Server, including complex queries, stored procedures, and performance tuning.

Build and ship customer-facing products across backend services, APIs, data models, React web interfaces, and Android point-of-sale applications. Learn unfamiliar platforms quickly, collaborate with product and design, deliver resilient code, and own testing, instrumentation, on-call support, and cleanup. The role emphasizes 0-to-1 product development, customer-focused decision-making, rapid experimentation, and using AI tools to improve development velocity and quality.

Build and maintain scalable e-commerce and marketplace features across Node.js, React, MySQL, and MongoDB. Own complex features end to end, design backend services and APIs, integrate PunchOut procurement systems, improve platform security and reliability, conduct code reviews, and mentor engineers. The role requires strong full-stack JavaScript and TypeScript expertise, e-commerce domain experience, and the ability to work autonomously on high-volume transactional software.

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.

Build and maintain the full-stack platform connecting Blissway hardware to drivers, partners, and agencies. Own public user surfaces, partner integrations (DMVs, mailhouses, fleet vendors, ACH), platform/deployment tooling, service infrastructure, and internal access management. Ensure secure, robust, production-ready systems and tooling that support a fast-moving, small engineering team.

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.

Design, develop, test, deploy, and support scalable full-stack cloud-native applications using Java, Spring Boot, Vue.js, Python, and FastAPI. Build secure APIs and operate AWS applications with Docker, Kubernetes, and Infrastructure as Code. Collaborate with product, systems, and architecture teams to deliver features end to end. Apply AI-assisted development throughout coding, testing, debugging, code review, and documentation while validating quality, security, and maintainability.

Leads technical direction and develops fullstack purchase experiences using Ruby on Rails and Vue.js. Designs resilient transactional flows, integrates billing and CRM systems, improves reliability and rollout safety, mentors engineers, reviews code, reduces technical debt, and participates in incident response. Partners with Product, Design, Billing, and Support to improve GitLab’s purchase, subscription, discount, and upgrade workflows.

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.

Contribute to full-stack features for spacecraft mission control and distributed ground control systems. Build React/TypeScript frontends and Elixir backend services, write maintainable and testable code, collaborate with operators, designers, and engineering specialists, and participate in design and code reviews. The role involves smaller, well-defined tasks under senior guidance during a three-month temporary engagement with potential conversion.

Own technical strategy and architectural decisions across multiple engineering squads. Design scalable distributed systems, APIs, data models, and cloud-native platforms while building shared systems that improve delivery. Partner with product and engineering leadership, resolve ambiguous technical challenges, establish AI-assisted development practices, and mentor engineers through design reviews and cross-team collaboration. The role requires full-stack expertise and strong influence, communication, and technical leadership in a high-stakes B2B SaaS environment.

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.

Develop and ship full-stack web and mobile experiences across Affirm’s consumer app and website. Collaborate with product, design, analytics, and engineering teams to break down projects, make technical decisions, write tested and extensible code, launch scalable APIs, monitor service health, support on-call operations, review code, and participate in team development and interviewing.

As a Fullstack Engineer, you'll design, build, and operate web applications, collaborating with product teams and mentoring peers while ensuring best practices in coding and system architecture.

Design and implement full‑stack, low‑latency web-based Ground Control Station and C2 systems (map-centric UIs, real-time telemetry, video streaming), lead architecture and APIs, mentor engineers, support field tests and mission deployments, and ensure interoperability with C2 standards.

Lead full-stack mission engineer who designs, develops, integrates, and deploys software for DoD/IC missions. Lead cross-functional teams to build high-performance frontends and cohesive systems, collaborate with military customers for product discovery, and deploy and field-test solutions in secure operational environments (travel ~1 week/month).

Build and scale consumer-facing mobile and web applications and backend services. Own features end-to-end across frontend and backend, optimize databases and queries, integrate third-party APIs, implement algorithms for risk and transaction evaluation, improve reliability and CI/CD, and contribute to testing, monitoring, and internal tools to support customer operations.

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.

Design, build, and maintain cross-platform mobile applications and end-to-end web features. Implement front-end interfaces, back-end services and RESTful APIs, optimize databases, write tests and documentation, perform code reviews, and collaborate with UX, QA, and DevOps to deliver high-quality, secure, and performant solutions.

Build and maintain scalable full-stack features for Roo’s veterinary staffing marketplace. Develop across the React Native mobile app and backend services, contribute to architecture, write unit and end-to-end tests, resolve production issues, improve observability and reliability, and support deployments and CI/CD. Collaborate with product, design, data, DevOps, and engineering teams while mentoring junior engineers and driving technical improvements.

Build and maintain core products and collaborate on larger consulting projects using TypeScript, Python, FastAPI, Next.js, GCP, and generative AI frameworks. The role involves hands-on software development within a rapidly growing, remote team serving Saudi Arabia and the GCC.

Build and ship enterprise WordPress features across frontend and backend, including custom Gutenberg blocks, React components, plugins, themes, PHP, HTML, and CSS. Own tickets from requirements through production, translate Figma designs into responsive experiences, use AI-assisted development responsibly, and collaborate asynchronously in English with distributed engineering, design, and delivery teams.