Senior Full-Stack WebApp Engineer

About the Role

Level is a learning technology company building interactive practice experiences for students. As a Senior Full-Stack WebApp Engineer on the Platform team, you'll own end-to-end feature slices spanning TypeScript/React frontends and Kotlin/Java backend services. Your work powers identity, accounts, onboarding, and authoring/admin surfaces that students, educators, and internal teams rely on daily. This is a full-time onsite role (5 days per week) in Bellevue.

Responsibilities

Feature Development

• Own full-stack feature delivery across the web client and supporting backend services — from UX and component work through API design, data modeling, and persistence.
• Design and evolve platform-facing web surfaces including authentication, account capture, invitation and onboarding flows, embedded authoring tools, and admin interfaces consumed by web, mobile, and native clients.
• Write clean, testable, maintainable code on both client and server; drive features from design through release and ongoing maintenance.

Architecture & Backend Services

• Architect and implement backend services and APIs (REST and gRPC) that support the web experience and scale across product surfaces.
• Make deliberate trade-offs on data modeling, contract design, and service boundaries; collaborate with backend architects on shared libraries and patterns.
• Contribute to platform direction through RFCs, architecture reviews, and decisions on shared libraries, frameworks, and developer tooling.

Performance, Reliability & Security

• Define and own reliability targets (SLOs/SLIs) for services you own; implement structured logging, metrics, and tracing aligned with platform standards.
• Profile and optimize client and server for latency, throughput, and cost — Core Web Vitals on frontend, p95/p99 latency on backend.
• Apply web security fundamentals (auth flows, session/token handling, CSRF, CORS, content security) with attention to K-12 student data privacy.
• Participate in incident response and post-mortems for systems you own.

Collaboration & Technical Leadership

• Partner with product, design, mobile, and infrastructure teams to translate requirements into technical designs and ship iteratively.
• Contribute actively to planning, technical discussions, code reviews, and release processes with practical input on feasibility and trade-offs.
• Maintain high standards of performance, stability, and test coverage; partner on test strategy, CI/CD, and performance benchmarks.
• Mentor mid-level and associate engineers through pairing, code review, and technical guidance; help shape team conventions and patterns.
• Identify and address technical debt, production issues, and scalability concerns.

Requirements

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).
• Expertise with state management, accessible UI patterns, and browser performance optimization.
• Strong backend proficiency in Kotlin or Java on the JVM (Kotlin is Level's primary backend language) or TypeScript for shared platform libraries.
• Solid understanding of HTTP, REST, gRPC, and protobuf; familiarity with Backstage service catalog.
• Experience with PostgreSQL data modeling for product features; knowledge of key-value and document stores (DynamoDB, Redis), caching, queues, and eventual consistency trade-offs.
• Working knowledge of AWS, containers (Docker/Kubernetes), and CI/CD pipelines as a consumer.
• Strong testing discipline — unit, integration, and end-to-end tests — with a track record of shipping reliably.
• Excellent written and verbal communication; ability to lead design discussions, write RFCs, and explain technical trade-offs to non-technical stakeholders.

Nice to Have

• Experience with authentication and identity systems (OAuth/OIDC, SSO, session and token management, third-party providers).
• Experience building authoring tools, CMSes, or internal back-office applications for operations teams.
• Familiarity with OpenTelemetry, structured logging, and observability platforms (SigNoz, Grafana, Datadog).
• Background in EdTech, K-12, or domains with strong privacy and accessibility requirements (FERPA, COPPA, WCAG).
• Experience with design systems and component libraries.
• Exposure to Backstage, internal developer platforms, or developer productivity tooling.
• Familiarity with Linkerd, ArgoCD, or Terraform.