Full Stack Engineer

Phonely, Inc.; San Francisco (CA); On-site; USD 120,000 - 160,000; Full time

Benefits offered by this job

Company-paid meals

Outdoor activities

Company trips to various locations

Job summary

A tech-forward voice AI company based in San Francisco seeks a Senior Full Stack Engineer proficient in React and Next.js. This in-office role emphasizes building high-performance web applications and includes working closely with backend engineers and various teams. Ideal candidates will have over 5 years of experience in production applications and a strong grasp of full-stack development. The company promotes a spirited culture with team meals, outdoor activities, and travel opportunities.

Qualifications

• 5+ years of experience building production applications.
• Strong experience with React and Next.js.
• Experience building full-stack applications with backend integration.

Responsibilities

• Build and maintain high-performance web applications using React and Next.js.
• Design and implement features across frontend and backend systems.
• Integrate APIs and voice AI workflows.

Skills

React

Next.js

TypeScript

API design

Performance optimization

Real-time systems

Async data flows

Product sense

Tools

AWS

GCP

Kubernetes

Firebase

Supabase

Datadog

Job description

Senior Full Stack Engineer (React / Next.js)

At some point in the future, every business will answer their phone with voice AI. We are making sure that when they build that AI agent, the experience of doing so doesn’t suck.

We’re growing incredibly fast and need someone who thrives in a dynamic, high-pressure environment to work across our engineering stack. This role is critical to the success of our company. We’re looking for someone who will roll up their sleeves, dig in, and double down when things get tough.

We want someone highly technical, driven, and fun to work with. You’ll be working directly with engineering, product, and customer-facing teams to build and ship fast.

NOTE: This is an engineering position. You will be writing a lot of code, and it will be a lot of work. If you’re looking for a cushy corporate job where nothing gets done, this is not the place. If you want to be part of a winning team and make a real difference, read on.

This role is in‑office 5 days a week in San Francisco.

Your Day‑to‑Day

• Build and maintain high-performance, responsive web applications using React and Next.js
• Design and implement end-to-end features across frontend and backend systems
• Work closely with backend engineers to integrate APIs, real-time systems, and voice AI workflows
• Own UI/UX quality—craft fast, intuitive, and reliable user experiences
• Manage state effectively across complex applications (server + client state)
• Optimize frontend performance (latency, rendering, caching, edge delivery)
• Build internal tools and dashboards for monitoring, debugging, and controlling AI agents
• Write clean, maintainable, and well‑tested code across the stack
• Debug production issues and continuously improve reliability and usability
• Contribute to system design, architecture decisions, and product direction

Qualifications

• 5+ years of experience building production applications
• Strong experience with React and Next.js
• Experience building full‑stack applications (API design, backend integration)
• Solid understanding of TypeScript, modern frontend tooling, and state management
• Experience working with APIs, real‑time systems, and async data flows
• Understanding of performance optimization and scalable frontend architecture
• Familiarity with cloud environments, CI/CD, and modern deployment workflows
• Strong product sense and attention to detail
• Clear communicator who can work across teams

Our Software Stack

• Frontend: React, Next.js, TypeScript
• Backend: Python, microservices, async systems
• Cloud & Infra: AWS, GCP, Kubernetes, Redis
• Databases: Firebase, Supabase
• Observability: Datadog, logging, metrics, tracing
• Voice AI: SIP, real‑time call handling, LLM orchestration
• Other: CI/CD, testing, resilient architecture

Why Join Phonely?

• We eat meals together (company‑paid)
• We run, hike, and surf
• We travel together (Airbnbs in places like the Rockies, Costa Rica, Indonesia—multiple times a year)