2x founder

Jack Brown

Founder @ Lark (YC S25)

Founder

Lark· Summer 2025 🇺🇸 San Francisco, California, United States

in LinkedIn

2025Founder· Lark

Founder · since 2018

Company

Lark

Role

Founder

current

Stage

—

no public source

Raised

—

no public source

Based

San Francisco, California, United States

current

Founder / co-founder — the company's markEmployee / research role

Source: LinkedIn work history

Profile coverage5 of 7 · missing posts, contact

Lark

The E2E testing layer for AI-driven development

Summer 2025

Experience

Career

Lark
Founder
Founder · San Francisco, California, United States · 2025 – Present
2025
Stripe
Software Engineer · 2024 – 2025
2024
Trustworthy
Lead Software Engineer · 2021 – 2023
2021
Xplor Technologies
Staff Backend Engineer · Boston, MA · 2020 – 2021
2020
LISNR
Backend Engineer · Cincinnati, OH · 2018 – 2020
2018
Vybe
Founder
Founder · Cincinnati, Ohio, United States · 2018
2018
Nasdaq
Full Stack Engineer Intern · Boston, Massachusetts · 2018
2018
Nasdaq
Data Science Intern · Boston, Massachusetts · 2017
2017

Bio

Jack is the co-founder of Lark. Previously, Jack built usage-based billing at Stripe to support the complex pricing models of the worlds biggest AI companies. Prior to his previous role, Jack led engineering teams at fast-growing startups, where he built developer tooling infrastructure to improve developer productivity.