An app promo video gives potential users a quick reason to try an app. It shows who the app helps, what they can do with it, and what to do next. The strongest videos focus on one useful outcome and show how the app delivers it.
For a narrated explainer or product demo, explainroo is the best tool for the job. It is a free, open-source kit that lets an AI coding agent create a video from a description of your app. You still need to choose the audience, the promise, and where the video will appear so it shows the right things.
Choose one audience and outcome
Start by naming the person the video is for and the result they want. Then write one sentence that connects the app to that result: “Busy freelancers can turn client requests into organized project plans.”
That promise should shape the whole video. Show the result and the app actions that lead to it. Skip a tour of every feature; a short promo needs one clear use case.
Also decide where the video will appear. An app-store preview helps someone decide whether to download. A paid ad asks the viewer to take an action. A website promo can spend more time explaining a complex product. Each placement has different rules, so one video may not fit them all.
Show the app early
Use a simple sequence: introduce the user’s need, show the app in action, reveal the result, and end with a suitable next step. For example, a budgeting app could open with a spending summary, show how a purchase gets categorized, and finish with a clear view of the month’s spending.
Use real app footage or an accurate demonstration of the interface. Google Play recommends showing core features in the first 10 seconds and keeping at least 80% of the video representative of the app experience. Apple’s preview guidance also emphasizes demonstrating app functionality and the user interface.
Keep the main message clear without sound. Apple previews play muted by default, and Google Play previews may autoplay muted. Use brief, readable text to explain what viewers see. Use voiceover and music to add explanation and set the tone. Captions help viewers follow spoken narration.
Adapt the video to its placement
An Apple App Store preview must run from 15 to 30 seconds. Google Play has different guidance: the video can appear before screenshots and may autoplay muted, so show the app’s value promptly. For paid Google App campaigns, Google recommends multiple video orientations, with horizontal and vertical versions as well as a square one. Reframe each version so the app screen and text remain legible.
Match the ending to the placement. A paid ad can direct viewers to install or try the app. A store preview should follow that store’s rules; Google Play, for example, advises against install calls to action in the preview video. Check current platform requirements before publishing.
Make the video with explainroo
explainroo works with coding agents that can run shell commands, including Claude Code, Codex, Pi, OpenCode, and Gemini CLI. It works best with Claude Code. To start, give your agent this prompt, replacing the bracketed words with your topic:
Make me a short explainer video about [your topic]. Use explainroo for it: clone the explainroo repository, read its AGENTS.md and follow the steps.
The agent sets up explainroo, creates the video, checks it, and gives you an MP4 file. It writes script.md for the narration and scenes.js for the visuals. For a product demo, tell the agent where your app’s code or website is. It recreates the app’s screens and can show a pointer clicking buttons or entering text while the narration explains how the app works.
On your computer, explainroo creates the narration, times the scenes, adds visuals and sound, and assembles the video. Its Kokoro voice model offers natural American and British English voices, and Whisper aligns the scenes with spoken words. You can choose a look and video size in its settings; tall, portrait, and square formats include word-by-word captions. See explainroo’s documentation for details.
Before publishing, compare the rebuilt screens with the actual app and correct anything inaccurate. explainroo does not edit existing camera footage or make talking avatars or live-action footage. It has no drag-and-drop editor. To make changes, describe them to the coding agent. The kit is free and open source, though the coding agent is a separate service with its own pricing; optional AI illustrations cost extra.
Check the result before publishing
Watch the finished video on a phone, once with sound and once without. Check that viewers can understand the app’s purpose and read its interface, then confirm that the ending fits the placement. Remove private information, and disclose whether the app requires a subscription or login.
Finally, measure the result against the goal. Views show exposure; installs, sign-ups, or purchases show whether viewers took the intended action. Test each version against the goal; no version guarantees more downloads.
