How It Works
DemoMatic is a command-line tool that takes a script, drives a real browser with Playwright, narrates with text-to-speech, and generates a video.
The script is a simple YAML file with three parts: what to say, what to do, and how long to wait.
The right voice for the job. It uses Piper for local, low-cost iteration, and ElevenLabs for the final polished demos.
Run it. Playwright launches a headless browser with native video recording, streaming frames to disk.
Get a video. FFMPEG combines browser video and audio into a single file. You get a video to download and upload wherever you’d like.
The script lives in version control. Made some UI changes? Simply tweak the script and re-run it.
Notes from Building
So it turns out, just like recording a demo yourself, the tool makes mistakes too. That became clear early on. Instead of burning through ElevenLabs credits from the start, we decided to start with Piper, a free, local text-to-speech engine. The goal was simple: test the tool quickly, iterate, and refine without worrying about costs.
What we didn’t expect was how Piper would transform our approach to iteration. The real value wasn’t in iterating on the tool itself; it was in perfecting the timing of the video. It was about getting the balance between the demo and the voice just right before committing to the final product. Instead of chasing the perfect demo right away, we realized it was about fine-tuning the process—nailing the pacing and flow first. Once we figured that out, we built the process around it:
Draft with Piper for fast, no-cost iterations. Nail the timing first.
Final take with ElevenLabs for that polished, professional finish.
And it worked—low-pressure demo videos without burning through credits on every iteration.
It’s still not quite the same as hearing someone talk through their work. The perfect product demo still needs that human touch. But this tool was a fun experiment in what happens when you bring all these tools together and streamline the process.
