DemoDay

Your software deserves a launch video. Let Claude film it.

DemoDay is a Claude Code plugin that turns any codebase into a finished, narrated demo video. Claude reads your repo, writes the script with you, drives your app on screen, narrates it with an AI voiceover — and hands you a polished MP4 with intro, captions, transitions and an optional on-camera presenter. One command, about the cost of a coffee. macOS only.

/demoday:create-demo-video

Not on Claude Code? DemoDay also installs as a Codex plugin and as an agent skill (npx skills add mrieck/demoday-claude-plugin) for Cursor, Copilot, Gemini CLI and every other agent that can run a shell — see Install.

🎬 See it in action

https://github.com/user-attachments/assets/8c122641-61c9-452c-aa34-293eea294419

Sample tutorial for Social Cue, a Claude Code plugin, in DemoDay's dynamic style: one AI presenter take re-framed over the screen, everything else filmed, narrated and cut by DemoDay.

Like what you see? ⭐ Star the repo — it's how people find it.

📱 Shorts

The same project can also be cut into a vertical Short for YouTube Shorts, Instagram Reels and TikTok — say "make a short" (or "vertical video", "Reel", "TikTok") and Claude picks one of the four vertical styles with you (see Styles below):

https://github.com/user-attachments/assets/5597a659-5655-4b5e-a2f7-8b77ba55d42a

Sample listicle Short for Social Cue, a Claude plugin that finds conversations worth joining. The presenter is an AI avatar made from a photo of the author, speaking with a designed ElevenLabs voice; the "it browses for you" beat is a Remotion animation instead of screen capture, timed to the narration word by word.

🎨 Styles

Every video starts from a named style — a complete look with sensible defaults (presenter mode, captions, transitions, pacing rules) that Claude picks with you at the start: "which of these is it most like?" Nine so far, five wide and four vertical. Anything a style sets can still be changed per scene.

Wide (16:9) — YouTube, a landing page, a README:

Vertical (9:16) — YouTube Shorts, Reels, TikTok:

✨ What you get

• 🖱️ Claude drives your app — it rehearses off camera first, then a deterministic runner performs the take with smooth cursor moves and human typing. No dead air, no fumbling.
• 🎙️ AI voiceover with word-timed captions — narration is generated first, so every scene lands exactly on the voice.
• 🧑‍💼 Optional on-camera presenter — an AI presenter for the intro, outro and cutaways, lip-synced to the same voice as the narration.
• 🧭 Nine named styles — five wide (launch, anchor, tutorial, dynamic, explainer) and four vertical (listicle, cohost, flashcard, glide), each a complete look Claude picks with you — see Styles.
• 🗣️ Custom character voices — describe a voice in plain English ("weathered lobster-boat captain, thick coastal accent") and the whole demo is narrated in it.
• 🎞️ Real editing, not a screencast — title cards, transitions, zoom-to-click, callouts, b-roll and audio ducking, rendered with Remotion.
• 📱 Vertical Shorts too — cut a 15–45s 9:16 Short (YouTube Shorts, Reels, TikTok) from the same project, with its own frame-0 hook card so the thumbnail is never a random frame.
• 💻 Films almost anything on a Mac — web apps, native macOS apps, and CLI/terminal programs (yes, it can demo a Claude Code plugin from inside a live claude session).
• 🔁 Cheap to iterate — change one line of narration and only that line is regenerated. A cost estimate is shown before anything is spent.

🚀 Install

In Claude Code:

/plugin marketplace add mrieck/claude-plugins
/plugin install demoday@productive-mark

(productive-mark is the marketplace, hosted in mrieck/claude-plugins; demoday is the plugin — this repo.)

That's it for software — no npm install, no manual dependency setup. The first time you run /demoday:create-demo-video, Claude checks your machine and installs anything missing (Node packages, a capture browser, ffmpeg) before filming starts.

Desktop scrolling also needs Xcode Command Line Tools (xcode-select --install). The capture tool compiles a small native scroll helper once and caches it in the temporary directory; doctor.mjs checks that the Swift compiler is available.

Requirements: macOS and Claude Code — or Codex, or any agent that can run a shell (both below). The only thing the agent can't do for you is the two steps that follow.

codex plugin marketplace add mrieck/demoday-claude-plugin
codex plugin add demoday@demoday

npx skills add mrieck/demoday-claude-plugin        # pick your agent(s) when prompted
npx skills add mrieck/demoday-claude-plugin -g -a cursor -a codex -y   # or non-interactively

1. Add your fal.ai key (required)

All generation — voice, presenter, b-roll — runs through fal.ai. Store the key in your macOS Keychain by running this in your own terminal (not through Claude, so the key never touches a transcript):

security add-generic-password -s demoday -a FAL_API_KEY -w

It prompts for the key without echoing it. A typical 30-second demo costs $1–2 in fal credits.

Not on Keychain terms? Every other place a key can live is covered in HOW_IT_WORKS.md.

2. Grant screen permissions (desktop capture only)

To film a native Mac app, give the terminal you run Claude Code from (Terminal, iTerm, VS Code…) Screen Recording and Accessibility in System Settings → Privacy & Security, then restart the terminal. Filming web apps and CLI demos in a staged terminal window needs no permissions at all — and if anything's missing, Claude tells you the exact Settings pane during preflight.

Optional keys

Same Keychain one-liner, different account name:

• ELEVENLABS_API_KEY — unlocks custom character voices via ElevenLabs Voice Design (affiliate link), and sound effects: a per-project pack of cues (whoosh, pop, hit, tick, riser) generated from text prompts and fired automatically on transitions, insert cards, #N stamps, punch-ins and bullet reveals — ~$0.02 a take, three takes per cue, pick your favourite. Needs a paid ElevenLabs plan (Starter and up): the free tier blocks voice creation over the API, and a paid plan also carries the commercial license you'd want for a published video anyway.
• BRAVE_API_KEY — lets b-roll generation search reference images.

🔒 What leaves your machine

Screen recordings, rehearsal screenshots and the finished MP4 stay local. Only what generation needs is uploaded: narration text, narration audio, the presenter image and b-roll frames go to fal.ai — and narration text to ElevenLabs if you use it. API keys are only ever read, never written (details).

🎥 Make your first video

From the repo of the software you want to show off:

/demoday:create-demo-video

Claude will read the codebase, pitch you two or three flows worth filming, ask about goal, audience, length and presenter style, and show you the cost estimate. Only after you say yes does it generate a single frame. Ten-ish minutes later there's an MP4 in that video's project folder under demo/ (each video gets its own, e.g. demo/project-overview/).

🔍 Under the hood

The interesting bits — the two-pass rehearse/perform design, narration-first pacing, the demo.json manifest, content-addressed caching, and everything about API-key resolution — live in HOW_IT_WORKS.md.

Meme-style cold opens (reaction clip + slow-mo cutout + freeze frame + music + push-in) are declared as a composite block on a scene and baked by scripts/edit/composite.mjs; scripts/gen/fetch-audio.mjs pulls a music cue with yt-dlp; scripts/gen/sfx.mjs designs the sound-effect pack and scripts/lib/sfx.mjs places every cue on the absolute timeline before the render. Every render rewrites SCRIPT.md from the manifest so downstream tools (cross-posting) always read the current cut.

🤖 Automation and social media

Want Claude to make videos while you sleep? Overboard is a Mac app that runs Claude Code agents 24/7 on the Claude subscription you already pay for. Put /demoday:create-demo-video on its scheduler and wake up to a rendered demo of last night's release, or dispatch a video from your phone over Telegram or Slack and let your Mac do the rest. No cloud server, no API bill. tryoverboard.com

Need a social media tool to grow your brand? Social Cue is a Claude Code plugin that finds the Reddit, Hacker News and X conversations your customers are already having, drafts replies in your voice, and cross-posts your DemoDay Shorts to YouTube, TikTok and Instagram with a title, post text and hashtags written for each platform. (The on-screen captions are burned into the video by DemoDay itself.) Every video on this README was scheduled with it. trysocialcue.com

⭐ If this saved you an afternoon

DemoDay is free and built by one person. If it made you a video you'd actually post, a star on this repo is the thing that helps other people find it — and it tells me which parts to keep building.

📄 License notes

Rendering uses Remotion, which is free for individuals and small companies but needs a paid license above a headcount threshold — see remotion.dev/license. Voices generated on a paid ElevenLabs plan include commercial usage rights.

To subscribe to an ElevenLabs plan that allows commercial use, click here (affiliate link).

DemoDay itself is MIT licensed.