Prove one path
TechCrunch's hackathon demo advice says to quickly set the scene, demo the working project, and then wrap with the dream. That order works because judges need context, proof, then a reason to remember it.
Devpost's planning guide says a demo video should show how the application works, explain the problem, and sell it. Do not tour the whole codebase. Show one user path that makes the project legible.
Win the first 30 seconds
AngelHack says judges see 30 to 100 demos and form opinions in the first 30 seconds. Your opening should name the user, the failure, and the result without a long origin story.
Karen Bajza-Terlouw told Devpost that storytelling in the video and text description helps keep judges engaged and focused. Storytelling here does not mean theatrics. It means the judge never wonders what they are looking at.
Skip setup and dead air
TechCrunch says the working demo is the most important part and advises skipping mundane flows such as account creation. If login, onboarding, or dataset upload is not the hack, pre-seed it.
A judge can read setup details later. During the demo, every click should move toward the aha moment. If the app needs a cold model call, a long import, or a flaky permission step, record a fallback path before judging starts.
Treat video as a first-class artifact
Richard Moot told Devpost that the demo video gives the most scope and is often the first indicator of time invested. In an online hackathon, that video may be the only thing a judge watches before scoring.
AngelHack recommends recording the demo twice and keeping screenshots as fallback against Wi-Fi drops, API rate limits, and model timeouts. The backup is not pessimism. It is respect for the room.
Respect the length rule
HackAI 2025 required a demo video of 2 minutes max. AI ATL 2025 asked for a roughly 5-minute demo video. Google Cloud Rapid Agent Hackathon required about a 3-minute demo video along with a hosted URL and public repo.
Those are different scripts. A 2-minute video needs one path and one proof point. A 5-minute video can show setup, result, and technical detail. A 3-minute sponsor demo should show the required platform in the core path, not in a footnote.
Use props when the real world is too large
Training Rails brought a fake rail to judges so the team could simulate real-time hardware detection without bringing a railroad into the room. That is the right kind of shortcut: fake environment, real signal.
Pull the Pitcher showed AI analysis of pitching mechanics with Vertex AI Gemini Pro Vision. Parable Rhythm's builder made the demo feel like a trailer for an interactive crime thriller. Different domains need different proof surfaces, but each demo made the project understandable fast.
< read by a human · updated as things change >
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