Founding Backend Architect for Enterprise SaaS

Proaction; San Francisco (CA); Hybrid; USD 180,000 - 260,000; Full time

Benefits offered by this job

Equity

Founding role

Job summary

Proaction is seeking a Founding Engineer to architect and scale its core platform. This is a hands-on, high-ownership role in a fast-moving, early-stage environment, reporting to the CTO to define system architecture and engineering standards.

You’ll build a modern TypeScript backend (NestJS), PostgreSQL and AWS-backed services, with a React frontend. You’ll own backend architecture, shape product and engineering culture from day one, and grow into long-term technical leadership as the company

Qualifications

• 5+ years of experience building and scaling production software systems.
• Proven ability to operate at a senior/staff level in system design and architecture.
• Strong backend fundamentals (data modeling, APIs, distributed systems, performance).
• Experience building or scaling enterprise SaaS platforms.
• Comfort working in ambiguity and bringing structure to messy systems.
• High ownership mindset: you take responsibility for outcomes, not just code.
• Low ego, high standards: you care about the best idea, not being right.
• Strong communication skills and the ability to influence technical direction.

Responsibilities

• Own backend architecture and system design for a multi-tenant, enterprise SaaS platform.
• Design and build durable, scalable workflows and core infrastructure systems.
• Lead technical decision-making with a pragmatic, long-term lens.
• Establish engineering standards across code quality, testing, deployment, and security.
• Partner closely with the CTO and product team to translate business needs into technical systems.
• Help shape the engineering culture: high ownership, low ego, strong collaboration.
• Be deeply hands-on: this is a building role, not a management role.

Skills

Backend architecture

System design

TypeScript

NestJS

PostgreSQL

AWS

React

SaaS platforms

Cursor

Tools

Cursor

Claude Code

Job description

Proaction is seeking a Founding Engineer to architect and scale its core platform. This is a hands-on, high-ownership role in a fast-moving, early-stage environment, reporting to the CTO to define system architecture and engineering standards.

You’ll build a modern TypeScript backend (NestJS), PostgreSQL and AWS-backed services, with a React frontend. You’ll own backend architecture, shape product and engineering culture from day one, and grow into long-term technical leadership as the company