Full Stack Engineer

Jack; San Francisco (CA); On-site; USD 160,000 - 220,000; Full time

Benefits offered by this job

Free lunch and dinner

Office gym

Equity

Direct founding team collaboration

Job summary

Jack in San Francisco invites applications for a Founding Engineer to build the ad network for AI experiences. You will own backend, ML, and infra work across a fast‑moving startup, collaborating closely with the founding team.

Ideal candidates have 0–3 years of engineering experience, a strong backend foundation, and a portfolio of side projects or open‑source work. This full‑time role requires in‑person presence in SF five days a week and US work authorization.

Qualifications

• 0–3 years engineering experience, including exceptional recent graduates.
• Strong backend engineering foundation across systems, infrastructure, and ML‑adjacent work.
• Demonstrated track record of side projects, personal products, or open‑source work.

Responsibilities

• Build and ship backend systems for AI‑powered advertising and related infra.
• Collaborate across backend, ML, and system design to ship what the team needs.
• Own features end‑to‑end from design through implementation and iteration.
• Develop scalable, immersive ad experiences inside AI entertainment products.
• Work directly with founders and early team members on product and technical decisions.
• Move quickly in a fast‑paced startup with changing priorities and ownership.

Skills

Backend engineering

ML

Infrastructure

Product execution

Communication

Open to side projects

Fast shipping

Tools

PyTorch

Git/GitHub

Job description

An early-stage, venture‑backed AI startup is hiring a Founding Engineer to help build the ad network for AI.

The team is creating immersive, personalized ad experiences for consumer AI entertainment and character platforms, including playable ads, animated character ads, sponsored experiences, and ad units that feel native to AI companions rather than disruptive to users.

This is a high‑impact founding role for someone who is deeply technical, highly self‑directed, and has a real track record of building outside of their day job. The ideal person is not just an engineer who completes assigned tickets, but someone who has shipped side projects, experimented with products, built systems from scratch, and can move quickly in ambiguous environments.

This role sits across backend engineering, ML, infrastructure, and product execution, with direct collaboration across the founding team.

Location: San Francisco, CA, 5 days in‑person

Employment Type: Full‑Time

Experience: 0–3 years

Compensation: $160,000–$220,000 + meaningful equity

Responsibilities

• Build and ship backend systems across AI‑powered advertising, consumer product experiences, and infrastructure.
• Work across backend, ML, and traditional system design depending on what the team needs to ship.
• Own features end‑to‑end, from technical design through implementation and iteration.
• Help develop scalable systems for personalized, immersive ad experiences inside AI entertainment products.
• Collaborate directly with founders and early team members on product, engineering, and technical decisions.
• Move quickly in a fast‑paced startup environment where priorities can change and ownership matters.
• Contribute to early engineering culture as one of the first technical hires.
• Figure things out independently, communicate clearly, and ship high‑quality work without needing heavy structure.

Qualifications

• 0–3 years of engineering experience, including exceptional recent graduates.
• Strong backend engineering foundation with comfort across systems, infrastructure, and ML‑adjacent work.
• Demonstrated track record of building outside of school or work, such as side projects, personal products, open‑source work, GitHub projects, startup projects, or technical experiments.
• High agency, high learning velocity, and the ability to ship fast in ambiguous environments.
• Comfortable working directly with founders and cross‑functional teammates.
• Able to communicate well with both technical and non‑technical people.
• Willing and able to work in‑person in San Francisco 5 days per week.
• Must already be authorized to work in the United States. Visa sponsorship is not available.

Strong Plus

• Experience or strong interest in recommendation systems, ranking, ad experiences, or marketplace‑style systems.
• PyTorch fluency or hands‑on ML implementation experience.
• Background at companies such as Roblox, Meta, Amazon, or similar consumer, ad‑tech, AI, or infrastructure‑focused environments.
• Strong side‑project portfolio that shows real building, not just coursework.
• Open‑source contributions or a notable GitHub presence.
• Experience shipping production systems, not just research prototypes.
• Interest in AI‑generated media, mobile entertainment, consumer AI products, or next‑generation advertising.
• Meaningful equity.
• Free lunch and dinner, including a $35 stipend through Uber Eats or DoorDash.
• Office gym.
• Direct working relationship with the founding team.
• High‑impact founding seat at an early company building infrastructure for the AI advertising ecosystem.

Who This Is Best For:

This role is best for someone early in their engineering career who has already shown unusual initiative through side projects, personal builds, startup work, open‑source contributions, or other evidence of shipping beyond a standard day job.

The team is especially excited by engineers who are fast, curious, technical, product‑minded, and comfortable building across backend, ML, and systems without needing a perfectly defined roadmap.