Turn an idea or script into a narrated explainer without editing stock footage. explainroo is a free, open-source tool that uses an AI coding agent, software that writes and runs code from text instructions, to create illustrated scenes and narration, set their timing, and render an MP4 video on your computer.
explainroo makes narrated explainers and product demos for people who prefer to request changes in text. Its MIT-licensed kit costs nothing per video. The coding agent is a separate service, and optional AI illustrations cost extra.
How explainroo creates narrated explainer videos
explainroo is built for narrated explainers and product demos. You describe the video to a coding agent, which writes a narration script and JavaScript that draws the scenes. explainroo then renders the video locally, adds audio, and creates an MP4.
The agent writes two main files: script.md contains the spoken words, and scenes.js describes what each scene draws. A drawing can appear at a chosen word. Kokoro, an open voice model, provides natural-sounding American and British English voices. It requires no account or API key, and narration is available only in English.
Whisper marks when each word is spoken in the recording, so scene changes can match the narration. Chrome draws frames on an HTML canvas. Rough.js adds hand-drawn lines, and Lucide provides icons. Scenes can include charts, code, and screenshots you provide. explainroo also creates background music and sound effects, and lowers the music while the voice speaks.
To begin, paste this prompt into a coding agent that can run shell commands:
Make me a short explainer video about [your topic]. Use explainroo for it: clone https://github.com/vincentsch/explainroo, read its AGENTS.md and follow the steps.The agent sets up explainroo, creates and checks the video, then gives you an MP4 file. You can run explainroo with coding agents that support shell commands. Compatible options include Claude Code and Codex, as well as Pi, OpenCode, and Gemini CLI. explainroo works best with Claude Code.
How explainroo compares with InVideo
How each tool builds a video
A common InVideo workflow combines a script, stock footage, voice, and edits. With explainroo, the coding agent creates a script and custom-drawn scenes, then explainroo renders and checks them. You tell the agent what to show and when, so you do not have to assemble footage scene by scene.
explainroo has no drag-and-drop editor. Instead, you ask the agent to update the script or scene code. In video.json, choose a visual style: paper, clean, chalk, blueprint, or midnight. A pace setting adjusts the voice, pauses, and animations. The available formats are wide, tall, portrait, and square. Tall, portrait, and square videos get captions that light up word by word.
How well they fit explainers
To explain how a process works, explainroo can draw a chart or a sequence of labeled scenes timed to the narration. For a product demo, tell the agent which product to show and where to find its code or website. The agent rebuilds the screens with the product’s colors, fonts, and button labels. It then adds a pointer that clicks through screens and types into fields as the narration explains.
This format suits videos that need timed visuals or a demonstration of a specific interface. A stock-footage workflow suits topics that depend on real-world footage. Choose based on what viewers need to see: a diagram or interface, or filmed imagery.
Check the free-plan limits
explainroo is free and open source under the MIT license. The kit itself costs nothing per video. Optional AI illustrations through OpenRouter are paid per image, and the coding agent has its own separate pricing. The initial setup downloads the voice and timing models once. No graphics card is needed.
This article does not list InVideo’s current free-plan limits for exports, watermarks, video length, assets, or credits. Check InVideo’s current plan details before comparing costs or choosing a workflow. explainroo’s free software does not cover the cost of related services, such as a coding agent.
Weigh the trade-offs
When explainroo makes sense
Choose explainroo for narrated explainers built from drawn scenes, charts, code, screenshots, or a product interface if you are comfortable giving a coding agent text instructions. Scene timing, multiple visual styles, different formats, and word-by-word captions help you build videos around spoken explanations.
You can try explainroo through an agent or install it yourself. To install it manually, you need a recent version of Node.js, ffmpeg, and Chrome or Chromium. Run these setup commands:
git clone https://github.com/vincentsch/explainroo.git
cd explainroo
npm install
node bin/explainroo.js doctor --fetchThe finished video is saved in videos/<name>/out/video.mp4. explainroo was developed and tested on Linux. It should work on macOS and Windows, but those systems have had less testing. explainroo does not edit existing camera footage or create talking avatars or AI-generated live-action footage.
When InVideo fits better
Choose a stock-footage workflow when your explainer depends on filmed imagery or you want to edit footage in an editor instead of directing a coding agent. explainroo offers a simpler way to make illustrated explainers and product demos, but gives you less hands-on visual editing through a graphical interface.
Check InVideo’s current free-plan terms and add the separate cost of any coding agent you use with explainroo before comparing prices. Choose explainroo for explainers built around narration and custom-drawn scenes. For footage-led editing, compare the workflow and plan limits with the video you need to make.
What to know before choosing explainroo
- Use explainroo for narrated explainers and product demos built from drawn scenes, charts, code, screenshots, or reconstructed product screens.
- Start with a coding-agent prompt that names your topic and asks the agent to follow explainroo’s
AGENTS.md. The agent then creates the video and provides an MP4. - Budget for the agent separately: explainroo itself is free per video, while the coding agent has its own pricing and optional AI illustrations cost per image.
- Check InVideo’s current free-plan terms directly before comparing export limits, watermarks, video length, assets, or credits.
Conclusion
explainroo is a free InVideo alternative for creators who want an agent to build narrated, illustrated explainers or product demos. Using explainroo requires a coding agent; creators make revisions through text. It does not support existing footage or live-action generation.
Use explainroo for videos about processes, diagrams, or product interfaces. For stock footage and graphical editing, check InVideo’s current plan terms to see whether its workflow fits.
