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Full-Stack Mobile/Web Software Engineer

Build cutting-edge mobile and web experiences for our AI companion platform. Work with React Native, Next.js, and modern cloud infrastructure to create seamless user experiences that blend beautiful 3D/AR experiences, voice, and contextual memory.

Location

Remote (Washington D.C., DMV area preferred)

Job Type

Intern or Full-time

Experience

1+ years of proven experience building mobile and web apps

Education

Bachelor's degree or equivalent experience

About Spirit

Spirit is an angel-backed, ambitious startup building an emotionally intelligent, ethically designed AI therapist that blends beautiful 3D/AR experiences, natural voice interaction, and contextual memory — all powered by cutting-edge AI. Our mission is to make personalized mental and emotional support accessible to everyone, creating an experience that feels empathetic, responsive, and genuinely human. We’re a lean, hands-on team where every engineer shapes meaningful parts of the product. You’ll work directly with founders, designers, and AI researchers to define how people connect, reflect, and heal through technology — from interface to infrastructure.

About the Role

We're looking for a Full-Stack Mobile (and Web!) Engineer who can take Spirit from prototype to production. You'll architect and build our cross-platform mobile app (iOS & Android), integrating real-time 3D avatars, LLM-driven interactions, and cloud-backed personalization. You'll own both the frontend (React Native + AR) and backend (Node.js, Python, AWS) layers, ensuring seamless communication between the mobile client, our AI services, and memory databases. This role is perfect for someone who loves both creative engineering and product thinking — designing interfaces that feel magical while ensuring the systems behind them are fast, secure, and scalable.

Responsibilities

  • â–¹Design and build Spirit's cross-platform mobile app (React Native + Expo or Flutter)
  • â–¹Design and build Spirit's 3D web app (NextJS, Typescript, Tailwind)
  • â–¹Implement immersive 3D and AR experiences using React Native ARKit, Three.js, or Unity as a Library for avatar rendering and animation
  • â–¹Develop APIs and backend services (Node.js + Express / NestJS or Python + FastAPI) that handle chat sessions, user memory, and personalization
  • â–¹Integrate LLMs and AI APIs (OpenAI, Anthropic, or local inference models) for conversational and emotional intelligence
  • â–¹Build real-time pipelines for chat, voice, and avatar interaction using WebSockets / Socket.IO
  • â–¹Design and manage databases for context persistence (PostgreSQL + Redis or MongoDB + vector search like Pinecone / FAISS)
  • â–¹Deploy and scale backend systems using AWS (ECS / Lambda / API Gateway / DynamoDB) or GCP Cloud Run + Firestore
  • â–¹Collaborate with designers to ensure fluid, emotionally resonant UI/UX — including transitions, animations, and interactions
  • â–¹Maintain best practices in testing, version control (Git), CI/CD (GitHub Actions), and code documentation
  • â–¹Drive architectural decisions for mobile performance, offline caching, and data privacy

Tech Stack

Frontend

  • •React Native (TypeScript), Flutter for iOS/Android and NextJS, TailwindCSS for Web App
  • •Expo / React Navigation / Redux Toolkit for structure
  • •Three.js, Babylon.js, or Unity (as plugin) for 3D/AR
  • •Lottie / Reanimated / Framer Motion for animation
  • •WebRTC / WebSocket / Voice APIs for real-time communication

Backend & APIs

  • •Node.js + Express/NestJS or Python + FastAPI
  • •GraphQL / REST API integration
  • •OpenAI, Gemini APIs for LLM integration
  • •WebSocket / Socket.IO for low-latency messaging
  • •Authentication via Clerk, Firebase Auth or Cognito

Database / Storage

  • •PostgreSQL / Supabase for structured data
  • •Redis / Pinecone / FAISS for embeddings and short-term memory
  • •S3 / Cloud Storage for media, voice, and avatar assets

Cloud Infra & Storage

  • •AWS (ECS Fargate, Lambda, API Gateway, S3, RDS) or GCP (Cloud Run, Firestore)
  • •Docker for containerization
  • •Kubernetes for container orchestration
  • •GitHub Actions / CircleCI for CI/CD
  • •Monitoring with Datadog or OpenTelemetry

Requirements

  • â–¹Proven experience building mobile and web apps (React Native or Flutter) from scratch
  • â–¹Solid backend development experience (Node.js or Python) and ability to design RESTful or GraphQL APIs
  • â–¹Strong grasp of frontend architecture, component design, and state management
  • â–¹Knowledge of databases (SQL and NoSQL) and cloud deployment pipelines
  • â–¹Familiarity with AI/LLM API integration (e.g., OpenAI, Hugging Face)
  • â–¹Excellent sense of UI/UX design, especially in animation, microinteractions, and user emotion
  • â–¹Passion for real-time systems, 3D interfaces, and AR experiences

Nice to Have

  • â–¹Prior experience with ARKit / ARCore / Unity3D
  • â–¹Experience optimizing 3D rendering or motion design on mobile
  • â–¹Exposure to LLM memory systems or vector databases
  • â–¹Familiarity with privacy-first data design and local caching
  • â–¹A personal app, open-source contribution, or creative tech project that showcases your imagination

Why Join Spirit?

  • â–¹Work directly with founders on a product that merges AI, art, and emotion
  • â–¹You'll ship live to users — not into a backlog
  • â–¹Learn cutting-edge tools in LLMs, AR, and 3D while shaping an early product from zero to launch
  • â–¹Contribute ideas to product, design, and AI direction — you're not just an engineer, you're a co-creator
  • â–¹Flexible remote setup, creative autonomy, and fast growth potential
  • â–¹Exceptional contributors will be considered for early equity and leadership roles
  • â–¹Be part of a collaborative, mission-driven team that values innovation, experimentation, and creative problem-solving

Compensation Note

We're an angel-backed startup looking to raise seed funding and hence we're mostly bootstrapping initially. Initially unpaid on onset for all members of the founding team but will be highly rewarded and compensated for their time and effort which includes:

  • â–¹Reimbursement compensation post-launch
  • â–¹Full-time employment options post-launch
  • â–¹Competitive salary
  • â–¹Equity benefits and stock options will be considered based on performance
  • â–¹Will be qualified for additional leadership roles within the company

Ready to Join Spirit?

Click below to fill out our application form