Backend Software Engineer

Company: Petra Security
Location: San Francisco, CA (in office 5 days per week; relocation support available)
Compensation: $170,000 - $220,000 + highly competitive equity
Employment Type: Full-time
Visa Sponsorship: Visa transfers (OPT, H-1B transfer)

Petra Security is an AI-powered cybersecurity platform that protects small and mid-size businesses from account takeover, focused on Microsoft 365 environments. Business email compromise has become the top way businesses lose money to cyberattacks, and Petra detects more attacks, responds faster and triggers fewer false positives than competitors, winning 90%+ of head-to-head evaluations.

A Y Combinator (W24) company with founders from Abnormal Security, Palo Alto Networks and Bridgewater, Petra reached mid-seven-figure ARR in under a year and protects 2.5M+ users across 10,000+ businesses with a team of about 20.

Petra is hiring a Backend / Distributed Systems Engineer (2+ years) to build and scale the AI-powered detection platform that stops account compromise in real time. You will join a small, high-caliber team, own critical infrastructure from day one and work directly with the founders.

• Design and build real-time account-compromise detection spanning signal ingestion, behavioral analysis and AI-powered decisioning.
• Architect backend infrastructure for 10-100x scale growth over the next six months.
• Ship ML/AI-integrated systems into production, not just prototypes.
• Establish engineering patterns and raise the technical bar.
• Evolve the core detection platform with the founders.

• 2-4 years in backend or distributed systems engineering
• Built high-stakes, data-intensive systems at scale (real-time ingestion pipelines, databases, distributed processing)
• Designed and built systems end to end with large ownership scope, ideally at a startup
• Distributed systems architecture and database scaling
• High agency: scopes, designs and ships without waiting for direction
• CS degree from a top US program
• Ability to work in the San Francisco office 5 days a week

• Quant/trading infrastructure or infra at top tech companies
• Performance-oriented languages (TypeScript/Node.js, Python, Go, Rust, Java, C++)
• Upward career trajectory from tier-1 companies

Healthcare, dental, vision, 401(k), meals, commuting stipend, Equinox discount, relocation support.

Phone screen (15-20 min), system design technical screen (60 min), onsite (3-4 hours).

Node.js, TypeScript, React, Python