Haystack
← Back to Jobs
Full time
Technology
PV

Fullstack Engineer - Known

Pear VcSan Francisco🇺🇸United StatesPosted 7 Oct 2025

Quick Overview

Seniority
Mid Senior
Employment type
Full Time
Location
San Francisco, United States
Posted
11 months ago
GCPNode.jsAWSA/B TestingGitLLMOnboardingReactReact NativeTypeScriptVercelWebSocket

Job Description

About the Role

You’ll be a core technical founder building the entire product surface of Known — from the mobile app users fall in love with, to the backend systems that power matching and conversation, to the API integrations that make dating effortless. You’ll ship features that blend beautiful UI, intelligent data flows, and third-party services into a cohesive, consumer-grade experience that feels magical.

You’ll work closely with the founding team (AI/ML, product, and design) to translate ambitious product ideas into production code. This is a high-ownership role where you’ll architect systems, make critical technical decisions, and directly shape how millions of users experience Known.

Responsibilities

  • Build and ship mobile experiences in React Native that are fast, delightful, and accessible — from onboarding flows to real-time messaging and match discovery.

  • Design and maintain backend services in Node.js/TypeScript, including RESTful APIs, WebSocket connections for real-time chat, and WebRTC integrations for audio/video experiences.

  • Integrate third-party platforms (OpenAI/Anthropic LLMs, Apple/Google Pay, reservation systems, SMS/push notifications) to deliver seamless, automated experiences.

  • Collaborate with AI/ML engineers to surface model outputs — compatibility scores, personalized recommendations, conversational agents — through intuitive UI and performant APIs.

  • Own infrastructure and deployment using modern cloud platforms, ensuring reliability, security, and scalability as we grow.

  • Implement analytics and instrumentation to measure user engagement, conversion funnels, and product health in real time.

Requirements

  • 3–5 years building production fullstack or mobile applications, ideally in consumer products or startups.

  • Strong proficiency in TypeScript, React, React Native, and Node.js.

  • Experience designing and scaling RESTful APIs with attention to performance, security, and maintainability.

  • Strong working knowledge of Postgres — you’re comfortable with data modeling, queries, indexes, and database performance.

  • Experience with cloud platforms (AWS, GCP, Vercel, Railway) for deployment and infrastructure.

  • Comfortable with modern development workflows: Git, CI/CD, feature flags, monitoring, and incident response.

  • Familiarity with WebSockets and WebRTC for real-time communication is a plus.

  • Passion for user experience and product quality — you care about polish, speed, and edge cases.

Example Projects

  • Design a reservation and payment integration layer that allows users to book dates, split costs, and receive confirmations — all within the app.

  • Create a real-time messaging system with typing indicators, read receipts, and optional AI-powered conversation starters using WebSockets and streaming LLM responses.

  • Build WebRTC infrastructure for voice and video chat between users and AI voice agents during onboarding and matching conversations.

  • Develop a modular component library for personalized UI cards (match suggestions, date ideas, conversation prompts) powered by ML model outputs.

  • Implement a feature flagging and A/B testing framework to enable rapid experimentation across mobile and web surfaces.

  • Expand the admin dashboard with new functionality for monitoring user activity, system health, and ML model performance metrics.

Why This Role

This is a chance to be a technical co-architect of a consumer AI product from the ground up — to own the entire stack and ship features that directly impact how people meet, connect, and fall in love. You’ll work at the intersection of design, data, and AI, with the autonomy to build systems your way and the responsibility to make them world-class.

Similar jobs