If you need a narrated explainer animation without paying for Adobe After Effects, explainroo is a free, open-source tool that builds video from a script and scene descriptions. A coding agent writes and runs the code, so you describe the video instead of assembling each element in a visual editor.
explainroo works well for short explanations and product demos. Use After Effects when you need detailed control over motion and visual effects; use explainroo when you want an agent to produce the video.
What explainroo creates
explainroo lets an AI coding agent create a narrated video on your computer. The agent writes script.md, which contains the narration, and scenes.js, which describes the visuals. explainroo then creates the video and saves an MP4 file.
For a basic explainer, you give the agent a topic and ask it to use explainroo. It builds scenes around the script, with drawings timed to words in the narration. For a product demo, tell the agent which product to show and where to find its code or website. It can recreate the product’s screens, including colors, fonts, and button labels, then show a pointer clicking and typing as the narrator explains.
Use this approach if you are comfortable describing a result to a coding agent. explainroo works with Claude Code, Codex, Pi, OpenCode, Gemini CLI, and other agents that can run shell commands. Claude Code has the strongest support.
explainroo vs. After Effects workflow
The main difference is who builds the animation. With explainroo, the agent writes scene code and the kit renders it. After Effects is motion-graphics software where the creator works directly on the animation. After Effects gives you direct control over the animation. With explainroo, you describe the video and the agent handles more of the production work.
Ease of making explainers
Ask your coding agent to use explainroo with a prompt such as:
Make me a short explainer video about [your topic]. Use explainroo: clone its repository, read
AGENTS.md, and follow the steps.
After setting up explainroo, the agent creates and checks the video, then returns an MP4. You can ask for changes by describing them. This avoids drawing and timing every scene by hand, though the workflow depends on a coding agent and does not provide a drag-and-drop editor.
The kit handles narration with Kokoro, an open voice model that offers voices in American and British English. Whisper marks when each word is spoken in the recording, so drawings can appear at the right time. Chrome renders the frames on an HTML canvas; scenes can use hand-drawn-looking lines, icons, charts, code, or screenshots. explainroo also creates background music and sound effects, then combines the parts into the MP4.
Control over motion and effects
explainroo includes settings for a video’s look and pace. Choose among paper, clean, chalk, blueprint, and midnight styles. Adjust the pace setting in video.json to change how quickly the narration, pauses, and animations move. Choose a wide, tall, portrait, or square format. Tall, portrait, and square videos include captions that light up word by word.
These controls suit explainers where clear visuals and narration matter more than custom motion design. After Effects is a better fit when a project calls for detailed animation or effects that need hands-on adjustment. explainroo’s scene descriptions are written in JavaScript, so someone willing to edit code has another way to shape the visuals, but the kit is not a full visual animation editor.
Free use, setup, and limits
explainroo is open source under the MIT license, and its video-making tools cost nothing per video. The coding agent is a separate service with its own pricing. AI-generated illustrations are optional and cost extra per image through OpenRouter, which provides access to AI image models. The rest of the video process has no per-video charge.
You can also install explainroo yourself with recent Node.js, FFmpeg, and Chrome or Chromium. After cloning the project, run npm install. Then run node bin/explainroo.js doctor --fetch to check dependencies and download the voice and timing models during setup. No graphics card is needed. The project was developed and tested on Linux; macOS and Windows have had less testing.
The finished file is saved as videos/<name>/out/video.mp4. Because the project documentation does not specify export-resolution or watermark limits, check those requirements before planning a delivery that depends on them. explainroo also does not edit existing camera footage, make talking avatars, or generate live-action video.
When to choose explainroo or After Effects
Choose explainroo for a narrated explainer or product demo when an agent-led workflow, its available styles, and an MP4 export meet your needs. It suits projects where you can describe the story and visuals clearly but do not want to create every scene by hand.
Choose After Effects when your project depends on fine-grained control over animation and effects, or when you want to work directly in a motion-graphics editor. Before deciding, check the deliverable’s required format and assess its visual complexity. Then consider whether you prefer to direct a coding agent or adjust the animation yourself.
Key Takeaways
- Use explainroo for agent-built explainers: Describe the topic, have a coding agent follow the project instructions, and review the resulting MP4.
- Match the tool to the work: explainroo handles narrated scenes and product demos; After Effects suits projects that need direct, detailed motion and effects control.
- Check costs and export needs: explainroo has no per-video fee, but the coding agent is separate. Optional AI illustrations cost extra. Verify any resolution or watermark limits.
- Review the video before delivery: explainroo provides scene stills and a contact sheet. It also checks for overlapping or cut-off text and words the voice misread.
Conclusion
explainroo is a free alternative to After Effects for narrated explainer animations and product demos created through a coding agent. It reduces hands-on scene assembly but offers less direct control than a dedicated motion-graphics editor.
Choose explainroo when its agent-led workflow fits the project. Choose After Effects when the animation needs detailed manual control.
