Full Stack Web Development Internship Jobs in California

We are seeking a highly skilled Senior Full Stack Tech Lead to join our engineering team. This is an individual contributor technical leadership role reporting to the Director of Software Engineering. You will drive the technical direction of your project area, write high-quality code across the stack, and act as the primary technical partner to product management, while mentoring engineers around you.

We've moved away from a frontend/backend split at Mill: every engineer here works full stack, typically leaning toward one side based on strength and interest, and teams are organized around projects rather than layers of the stack. You'll likely anchor on a given project for a sustained stretch - enough to build real depth and avoid constant context-switching - with real opportunities to rotate onto new projects and parts of the codebase over time.

AI-assisted development is core to how we build software, not a peripheral tool. We expect fluency with tools like Claude Code as part of your daily workflow, and as a senior level engineer, a role in raising the bar for how the team uses them.

Technical Leadership

1. Lead the technical design and execution of full-stack web applications, ensuring alignment with business objectives and technical standards
2. Architect and implement scalable, secure, and efficient full-stack solutions
3. Evaluate and select technologies, frameworks, and tools - including AI-assisted development tooling - to improve team productivity and code quality
4. Own estimates and technical delivery plans for your project area, and surface risks early

Development and Implementation

1. Craft elegant, documented, and sustainable code spanning our full web stack, remaining ready to provide support for our native mobile environment when required
2. Develop and optimize APIs, databases, and user interfaces
3. Use AI-assisted development tools fluently as a standard part of how you write, review, and ship code

Team Collaboration & Product Partnership

1. Mentor engineers, fostering a culture of continuous learning and improvement
2. Conduct code reviews and provide constructive feedback to maintain high coding standards
3. Act as the primary technical partner to product managers on your project - informing scope, sequencing, and tradeoffs - even though roadmap ownership sits with the PM

Quality Assurance

1. Champion best practices in testing, CI/CD, and deployment
2. Troubleshoot and resolve technical issues, ensuring minimal downtime and disruption
3. Monitor and optimize application performance

• 6+ years of professional experience in software development with a focus on full-stack development
• Deep experience with modern frontend frameworks (e.g. React, Vue, Angular, or SvelteKit) - we use SvelteKit at Mill but recognize that strong React/Vue/Angular experience is highly transferable, especially with AI-assisted tooling, so prior SvelteKit experience is preferred but not required
• Strong backend experience with TypeScript/Node.js; comfort with serverless architectures (e.g. AWS Lambda) is a plus
• Solid understanding of SQL and NoSQL database systems
• Experience with cloud platforms (we run AWS) and modern deployment workflows
• Fluency with AI-assisted development workflows (e.g. Claude Code, Copilot) as a genuine part of your day-to-day practice - not occasional or exploratory use
• Strong software architecture fundamentals (e.g. microservices, serverless)
• Excellent problem-solving and debugging skills

• Experience with our specific stack: SvelteKit (web, deployed on Vercel), React Native (mobile), AWS Lambda with CDK (TypeScript) and Middy
• Familiarity with DevOps practices and infrastructure as code (e.g. Terraform, CDK)
• Strong understanding of security best practices in web development
• Prior experience working at a hardware company, particularly collaborating with firmware teams - we build physical devices, not just software, and comfort working alongside hardware/firmware engineers is a plus
• Prior experience in a people-management role, or clear interest and readiness to grow into one over time. This role does not manage people today, but we're looking for someone open to taking on direct reports as the team scales

• Strong communication and interpersonal skills - especially the ability to partner closely with product without owning the roadmap
• Comfortable holding technical ownership of a project over a sustained period, while staying energized by the opportunity to rotate onto new problems periodically
• Proactive, self-driven, and eager to take ownership of projects
• Passion for mentoring and developing engineering talent

The estimated base salary range for this position is $185k to $225k, which does not include the value of benefits or a potential equity grant. A wide range of factors are considered in making compensation decisions, including but not limited to skill sets, market conditions, experience and training, licensure and certifications, and business and organizational needs.