Show HN: Get a demo video with AI voiceover using DemoFly

Hi HN, I'm Matt, one of the engineers behind DemoFly!

We built DemoFly because we got tired of the gap between building features and showing them to people. Our team has been doing full-stack engineering for over a decade (most recently building Rownd, an authentication platform) and the one thing that never got easier was making demo videos. You finish a feature, you know it works, but showing it to someone means opening a screen recorder, figuring out what to say, re-recording when you stumble. So the demo just...doesn't happen.

DemoFly is a CLI tool. You point it at whatever you're building and it autonomously navigates your app using Playwright + image recognition, then produces a polished video with AI-generated voiceover. No screen recording, no scripting on your part.

How it works technically: - Node-based CLI. You run demofly against localhost or any browser-accessible target. - Playwright drives a headless browser. Image processing observes the rendered UI and decides what to interact with next. - As it navigates, it builds a narrative of what it's seeing and doing. - That narrative becomes a voiceover script, synthesized locally with AI TTS (kokoro). - Video is composited from the browser session frames + voiceover audio. - Output uploads to a dashboard where you can review, edit, and share.

What it's good at: Standard CRUD apps, multi-page flows, dashboards. Works well for "hey, check out what I built on this branch" type demos. Fits into CI if you want auto-generated changelogs or PR previews.

What's not perfect yet: Auth flows can trip it up (ironic, given our background in auth). Highly dynamic SPAs with lots of client-side state might confuse the navigation model. Canvas/WebGL/Video elements are mostly opaque to it. Voiceover occasionally describes something slightly wrong.

Pricing: Free tier has every feature, so no credit card is needed and there are no feature gates. Paid tiers just give you more credits for higher quality voices and output.

Grab the CLI, run your first demo, and roast our AI's narration! We’re ready for the feedback. I think...