Fulltime Software Engineer Startup Jobs in California

Job Title: Junior Software Engineer w/ Equity (Engineering Automation Startup) (Ivy League Schools Only)

Location: San Francisco, CA (in-person)
Job Duration: Full-Time/Permanent

Job Overview
Are you an ambitious early-career software engineer eager to work at the cutting edge of engineering automation? Join a dynamic San Francisco-based team dedicated to creating a state-of-the-art platform that unleashes the potential of AI agents in real-world software engineering. As a pivotal team member, you'll transform ambitious product ideas into solid, production-grade systems, linking prototypes with reliable delivery. Your expertise in full-stack development will be crucial as you ship end-to-end solutions on a platform where AI agents execute complex engineering workflows. You'll build the backend in Python and the frontend using TypeScript/React.

Your role will involve designing and implementing evaluation scenarios and production-grade loops, focusing on meaningful engineering tasks and establishing robust infrastructures like unit tests and regression suites. You will also champion safety-first systems, designing and implementing risk-detection measures, fallback paths, and human-in-the-loop escalations to ensure system safety is integral to the product. Working closely with design and research teams, you will translate findings into product enhancements, driving rapid prototyping and weekly releases while documenting critical decisions.

Candidates should have 0-2 years of engineering experience, proficiency in Python, and a robust grasp of full-stack development. A successful history of shipping real products and a passion for iterative innovation in high-ownership environments are essential. You must be available to work in person in San Francisco and must be legally authorized to work in the U.S. without sponsorship. This position offers equity, allowing you to grow as a technical leader within our pioneering startup.

Key Responsibilities

• Ship end-to-end full-stack systems: Build the core simulation platform where AI agents execute software engineering workflows (backend in Python, frontend in TypeScript/React).

• Design realistic evaluation scenarios and production-grade loops: Define meaningful engineering tasks, establish grading criteria, choose tooling and workflows, and build infrastructure (unit tests, regression suites, shadow/prod checks) that measure reliability and user outcomes.

• Build and iterate safety-first systems: Implement risk-response detection, guardrails and fallback paths, human-in-the-loop escalation, post-incident reviews, and treat system safety as a first-class product feature.

• Own critical internal services and tooling: Build lightweight internal tools (UX hooks, service APIs, automation) that speed up experimentation and engineer feedback loops.

• Collaborate across disciplines: Partner with design (voice/chat UX) and research teams (for measurement and impact) to translate findings into product improvements and safety safeguards.

• Drive a high-cadence shipping culture: Prototype, evaluate, harden, and release weekly; document decisions and metrics to build confidently and scale fast.

Qualifications

• 0-2 years of experience as a software engineer with fluency in Python.

• Proven track record of shipping real products (internships or full-time) and love for the design → measurement → iteration loop in small-team environments.

• Strong software engineering fundamentals: Hands-on experience with full-stack development (TypeScript/React or equivalent), building tools/features that real users touched—not just prototypes.

• Product-sense plus speed: Simplify ambiguous problems into pragmatic baselines, deliver value in days, and iterate rapidly while maintaining high standards.

• Experience with system quality and safety: Built guardrails (error detection, fallback paths, monitoring) and accountable for production quality and sustained value.

• Evidence-driven mindset: Instrument features, define measurable outcomes, and iterate based on data and feedback loops.

• Thrive in high-trust, high-ownership teams: Excel building in-person with cross-functional partners; excited to raise questions, shape architecture, and drive standards.

• Must Have: In-person work in San Francisco required; legally authorized to work in the United States without sponsorship; proven track record of shipping software features end-to-end.

Ideal Candidate Profile
We're seeking a high-bar early-career software engineer who matches ambition and craft with deep ownership. You've shipped real software (internship or full-time), playing a substantial role from discovery → design → implementation → iteration. You're fluent in backend engineering (Python) and comfortable across full-stack (e.g., TypeScript/React). You've worked in production, understanding trade-offs, instrumenting outcomes, and speaking to reliability, performance, and user-impact. You treat safety and quality as features, designing guardrails, fallback paths, monitoring, or systems ensuring responsible production behavior. You thrive in high-ownership, in-person environments, collaborating closely, iterating fast, and shaping builds.

Bonus Signals
Experience at a top-tier tech company or startup, or from a competitive engineering program—with a mindset of building for the next level.