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Founding Full-Stack Engineer

FitNext Co.
San Francisco, CA Full Time
POSTED ON 1/7/2026
AVAILABLE BEFORE 3/7/2026
Founding Full-Stack EngineerIndustry: Sales Technology | Generative AI Stage: Seed | Scaling to $1M ARR Salary: Competitive, based on experience Location: San Francisco, USA (On-site) Job Type: Full-TimeAbout The CompanyThe company is the world's first unified revenue acceleration platform built natively on generative AI. We help sales teams at companies like Lenovo and Redpanda ramp faster through AI-powered training and coaching, instantly surface and personalize sales collateral, and engage buyers through the industry's first AI Sales Room.We've raised $2.7M in seed funding from top-tier investors including Y Combinator, Formus Capital, Soma, Pioneer Fund, and TechNexus. As we scale beyond $1M ARR, we're building our founding team and looking for engineers excited to shape both the product and the company from the ground up The RoleWe're hiring a Founding Full-Stack Engineer as one of our first engineering hires. You'll have a major influence on product direction, engineering culture, and company growth, working directly with leadership to define how our platform evolves.This is a high-impact role with real ownership over customer-facing, AI-powered features.What You'll DoBuild high-performance, responsive customer-facing features using Python, React, Redux, and TypeScriptDesign and implement LLM-powered features across text, image, video, and audioCollaborate closely with backend engineers on integrations and architectureDevelop APIs and frontend integrations for scalable, AI-driven workflowsWork directly with customer feedback to continuously improve UXOwn features end-to-end, from concept to productionWhat We're Looking ForRequired Qualifications3 years of experience in full-stack software developmentStrong experience with TypeScript/JavaScript, React, and PythonExperience with API integration and modern web architecturesSolid understanding of database fundamentalsFamiliarity with AWS, Terraform, and cloud infrastructureExperience with automated UI testing frameworksPrior experience with or strong interest in Generative AIStrong communication, collaboration, and problem-solving skillsWhy Join Letter AIBe part of the founding engineering team at a fast-growing AI startupHigh ownership and autonomy over product and technical decisionsCompetitive compensation and meaningful equityDirect impact on customers, product direction, and company cultureHow We OperateAt Letter AI, we encourage everyone to be unapologetically themselves while operating by our core principles:Customer-obsessed: Make customers unreasonably happyAmbitious yet practical: Set bold goals and execute with disciplineDirect yet kind: Speak openly, always with respectDriven yet humble: Move fast, aim high, stay groundedWork Authorization (Important)Candidates must have unrestricted authorization to work in the U.S.Visa sponsorship is not available now or in the futureWork authorization will be confirmed during the screening process

Salary.com Estimation for Founding Full-Stack Engineer in San Francisco, CA
$79,618 to $102,456
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