Member of Technical Staff, Full Stack

About Pepr AI

We are building the AI Operator for growth to replace traditional ad agencies. We apply quant rigor of high-frequency trading to optimize ad spend, delivering 20-50% upside in spend efficiency. We manage spend for global category leaders like Cider and Cupshe with a clear path to managing billions of dollars. We are backed by Quiet Capital and are looking for early engineers.

The Role

We are looking for a Full Stack Engineer to own the trust layer between Pepr and its customers.

Our system makes financial decisions with real money. Trust is earned by delivering impact and proving it with evidence. Your job is to build the surfaces that make every dollar of value visible, every decision explainable and every outcome quantifiable.

Every surface you build must answer three questions: What did we do? Why did we do it? What was the result? But different people need different answers. A CMO needs an overview of portfolio performance. A Head of Meta Ads needs control over channel-level decisions. A Marketing Manager needs to understand why a specific campaign was paused. A CFO needs audit-ready numbers. You will design the persona-aware interfaces, approval workflows and exploratory tools that make this possible, and lead the transition of Pepr from a white-glove service to a self-serve platform where every dollar of impact is accounted for and every decision has a paper trail.

What You'll Do

• Design the Evidence Layer: Build the UI that shows why the AI made a decision and what it achieved. You will translate causal data into Rationale cards that connect every action to a measurable outcome.

• Build Persona-Aware Interfaces: Design role-based views that give a CMO portfolio clarity, a channel lead operational control, a marketing manager campaign-level context and a CFO audit-ready financials, all from the same underlying data.

• Engineer Approval & Control Workflows: Build the human-in-the-loop systems for high-stakes decisions. You will design approval flows, guardrails and escalation paths that let teams authorize spend changes, override recommendations and set boundaries on what the system can do autonomously.

• Develop Exploratory Analytics: Integrate LLMs to power open-ended investigation. You will build interfaces where users can ask natural language questions, chase down anomalies and receive data-backed answers with generated charts and experiment readouts.

• Engineer the Slack Operating System: Build Slack integrations for anomaly alerts, impact notifications and approval flows that let humans authorize decisions without leaving the chat.

Who You Are

• Communicator of Complexity: You excel at progressive disclosure. You know how to present outcomes to an executive while keeping the evidence accessible for the analyst.

• A Builder Who Ships: You have 4+ years of experience building full-stack web applications. You take ambiguous problems and deliver working software. You care more about outcomes than process.

• High Agency: You see a gap where users lack clarity and you build the surface that closes it.

• Technically Fluent: You are proficient in React + TypeScript on the frontend and Python or Node.js on the backend. You pick the right tool for the job and learn fast.

Bonus Points

• LLM Integration: Experience streaming text and structured data to the frontend.

• Slack App Development: Experience building Slack apps using the Bolt framework or similar.

• Component Libraries: Experience building or maintaining a design system.

• Startups: You have built a product from zero to one and know how to iterate based on user feedback.

Compensation & Benefits

• Salary: $140,000 – $225,000

• Equity: Significant equity package

• Food: Daily lunch and (optional) dinner

• Relocation: Relocation support for candidates moving to the Bay Area

• Benefits: Comprehensive health, dental, vision and unlimited PTO