Build online. Demo in Paris. Join Paris builders for a community hackathon ahead of DevDay Exchange. Create a project with Codex or the OpenAI API, then join an evening of demos, judging, and conversation.
Hosted by Hexa and Boris de Wit, your local Codex Ambassador.
10 tickets to DevDay Exchange
Compete for one of 10 tickets to the official DevDay Exchange in Paris on 28 October.
How it works
24–26 October · online build weekend
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Join the online kickoff on 24 October at 10:00 AM, Paris time, and meet fellow builders.
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Come with a team or work solo. There will be time to form teams at the kickoff. Teams can have up to 4 people.
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Build with Codex or the OpenAI API
26 October · Demo night
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Present your project in a short demo with Q&A.
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Get feedback from judges and fellow builders.
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Celebrate the winners and meet the Paris community.
Choose your ticket
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Hackathon participants: join the online build phase, kickoff, and demo night.
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Demo night visitors: come along on 26 October to watch the demos, meet builders, and celebrate the winners.
Finale programme
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18:00 — Doors open, introductions, and final demo preparation
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18:30 — Welcome & learn what's new in Codex
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19:00 — Project demos and Q&A
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20:30 — Winners announced, celebrate with snacks and drinks 🤩
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22:00 — Event ends
When
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Online kickoff: Saturday, 24 October 2026 at 10:00 AM, Paris time
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Online build phase: 24–26 October 2026
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In-person finale: Monday, 26 October · 18:00–22:00, Paris timr
The date and time at the top of this page refer to the in-person finale.
Our host, Hexa, is a startup studio, partnering with founders to build ambitious companies from day zero.
This community-led hackathon is separate from the official DevDay Exchange in Paris on 28 October. Registration does not include admission to the official event.
