Senior Full Stack React Developer Jobs in Seattle, WA

Job Summary:
Level is a learning technology company dedicated to helping students build real academic and life skills with confidence and joy. As a Senior Full-Stack WebApp Engineer on the Platform team, you will own end-to-end slices of Level's web experience, architect and ship features, and directly impact the experiences of students, educators, and internal users.
Responsibilities:
• Own full-stack feature delivery across the web client and its supporting backend services — from UX and component work down through API design, data modeling, and persistence.
• Design and evolve platform-facing web surfaces — authentication, account capture, invitation and onboarding flows, embedded authoring, and admin tooling consumed by web, mobile, and native clients.
• Implement clean, readable, testable code on both client and server; take responsibility for features from initial design through release and ongoing maintenance.
• Architect and implement backend services and APIs (REST and gRPC) that back the web experience and are reused across product surfaces.
• Make explicit trade-offs on data modeling, contract design, and service boundaries; partner with backend architects on shared libraries and patterns.
• Contribute to platform direction through RFCs, architecture reviews, and decisions about shared libraries, frameworks, and developer tooling.
• Define and own reliability targets (SLOs/SLIs) for the services you own; implement structured logging, metrics, and tracing on top of platform standards.
• Profile, optimize, and tune both client and server for latency, throughput, and cost efficiency — Core Web Vitals on the front-end, p95/p99 on the back-end.
• Apply web security fundamentals (auth flows, session/token handling, CSRF, CORS, content security) with particular care for student data and K-12 privacy requirements.
• Participate in incident response and post-mortems for what you own.
• Partner with product, design, mobile, and infrastructure engineers to translate product intent into concrete technical designs and ship them iteratively.
• Participate actively in planning, technical discussions, code reviews, and release processes — contributing practical input on feasibility, trade-offs, and implementation details.
• Ensure high standards of performance, stability, and test coverage across the web surfaces and services you own; partner with our DevProd lead on test strategy, CI/CD, and performance benchmarks.
• Actively contribute to improving web architecture, technical foundations, and developer experience.
• Identify and address technical debt, production issues, and scalability concerns — leave the code better than you found it.
• Mentor mid-level and associate engineers through pairing, code reviews, and technical guidance; help shape the conventions and patterns the rest of the team adopts.
Qualifications:
Required:
• 5+ years of professional full-stack web engineering experience shipping production systems used by real users.
• Strong proficiency with TypeScript and a modern component framework (React preferred — React Native experience a plus given our direction on client shells); state management, accessible UI patterns, and performance optimization in the browser.
• Strong backend proficiency in Kotlin or Java on the JVM (Kotlin is Level's primary backend language) or TypeScript for shared platform libraries and tooling; comfort designing and operating long-lived services.
• Solid understanding of HTTP, REST, and gRPC + protobuf — Level's primary service-contract framework, with Backstage as the service catalog.
• Experience with PostgreSQL and data modeling for product features; familiarity with key-value / document stores (DynamoDB, Redis) and with caching, queues, and eventual-consistency trade-offs.
• Working knowledge of AWS, containers (Docker / Kubernetes), and CI/CD pipelines as a consumer — you don't need to own clusters, but you should be effective in them. Familiarity with Linkerd, ArgoCD, Terraform is a plus.
• Strong testing discipline — unit, integration, and end-to-end — and a track record of partnering with QA/DevProd to ship reliably.
• Excellent written and verbal communication; ability to lead design discussions, write clear RFCs, and represent technical trade-offs to non-engineering stakeholders.
Preferred:
• Experience with authentication and identity systems — OAuth/OIDC, SSO, session and token management, third-party providers (Google, Discord, Apple, etc.).
• Experience building authoring tools, CMSes, or internal back-office applications used by editorial/operations teams.
• Familiarity with OpenTelemetry, structured logging, and modern observability stacks (SigNoz — Level's stack — Grafana, Datadog).
• Background in EdTech, K-12, or other domains with strong privacy and accessibility requirements (FERPA, COPPA, WCAG).
• Experience contributing to or maintaining shared design systems and component libraries.
• Exposure to Backstage, internal developer platforms, or other developer productivity surfaces.
Company:
Level is a learning technology that blends proven curriculum with interactive design to aligned practice tools for students, teachers. Founded in , the company is headquartered in Austin, TX, US, , with a team of 51-200 employees. The company is currently Growth Stage.