2x founder

Jules Testard

Co-Founder and CEO at GCast: gcast.app

Founder

Jam.gg (formerly Piepacker)· Summer 2020 🇫🇷 Paris, Île-de-France, France

in LinkedIn 𝕏 @julestestard

2025Founder· GCast

Founder · since 2020

Company

GCast

Role

Founder

current

Stage

—

no public source

Raised

—

no public source

Based

Paris, Île-de-France, France

current

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

Source: LinkedIn work history

Profile coverage5 of 7 · missing posts, contact

Jam.gg (formerly Piepacker)

Jam.gg, play couch games online with friends

Summer 2020

Experience

Career

GCast
Founder
Founder · Paris, Île-de-France, France · 2025 – Present
2025
Jam.gg (formerly Piepacker)
Co-founder
Co-Founder and CTO (YC S20) · France · 2020 – 2025
2020
MadHive
Senior Software Engineer · New York City Metropolitan Area · 2019 – 2020
2019
Docker, Inc
Software Engineer · San Francisco Bay Area · 2017 – 2019
2017
Amazon Web Services
Software Engineer · San Francisco Bay Area · 2016 – 2017
2016
UC San Diego
Ph.D. (started) · 2013 – 2016
2013
Informatica
Software Engineer Internship · San Francisco Bay Area · 2015
2015
Yelp
Software Engineer Internship · San Fransisco · 2014
2014
Inria
Research Assistant · École normale supérieure de Cachan · 2012
2012
Morgan Stanley
Summer Technology Analyst · 2012
2012
École Normale Supérieure de Cachan
Research Assistant · 2011
2011
THEM www.them.pro (Search Engine Optimization and Website Development)
web developer · 2010
2010

Bio

Former academic researcher at UCSD. Worked as a software engineer at AWS, Docker and Madhive. Loves distributed systems, hacking things together quickly, surfing and gaming.