Schemio is a web-based diagramming app for building interactive diagrams — and, as a secondary use, prototypes — aimed at people who need diagrams that viewers can click, explore, and navigate inside a browser rather than look at as static images.

What it is

Schemio is a JavaScript diagramming application that runs in the browser and produces diagrams whose items respond to events, link to other documents, and animate. The project lives in the web front-end ecosystem rather than the desktop drawing-tool world, and its stated purpose is interactive diagrams first, with prototyping as a capability the author notes it was not originally designed for. Diagrams are documents that can embed other diagrams, so a single page becomes a navigable structure instead of a flat canvas.

The concrete problem it replaces is the static exported image. A conventional diagram ends the moment it is saved as a picture: the reader cannot follow a connection to another diagram, cannot inspect documentation attached to an individual item, and cannot walk through a sequence step by step. Schemio addresses this by letting an item carry a link to another diagram or an external document, by allowing one diagram to be loaded dynamically inside another, and by assigning event handlers to items. The result is a document a reader keeps exploring while remaining in the original diagram.

Key capabilities

• Behavior editor that assigns event handlers to any item, with events including init, click, mouse in, and mouse out.
• Component-based diagrams, where one diagram is loaded dynamically inside another so large documents are managed as smaller reusable parts.
• Linking from diagram items to other diagrams or to external documents.
• Relative transformations, attaching items to other items and adjusting rotation, pivot point, and scale.
• Free-form shape drawing, plus a frame animation editor that animates any property.
• Animation functions for smooth transitions such as fade in, fade out, and item movement, including particle effects.
• SVG export of the entire diagram or only the selected objects, and static generation of all diagrams for hosting anywhere, including GitHub Pages.
• Server configuration through environment variables: SERVER_PORT, FS_ROOT_PATH, FILE_UPLOAD_MAX_SIZE, VIEW_ONLY_MODE, and ROUTE_PREFIX.

Who uses it and how

• Documentation and knowledge-base authors. The official demo, ishubin/sre-knowledge-base, uses Schemio to answer the interview question "What happens when you open a website in your browser."
• Publishers who want no server at all, by generating a static version of all diagrams and hosting it on GitHub Pages.
• Self-hosters running the Docker image binshu/schemio:latest, mounting a volume and storing diagrams and uploaded files under FS_ROOT_PATH (default /opt/schemio) on port 4010.
• Teams running Schemio behind a load balancer next to other services, using ROUTE_PREFIX (for example /schemio) to serve it on a shared port.
• Read-only audiences, where VIEW_ONLY_MODE=true disables editing and permits viewing of folders and diagrams only.

Getting started

The README gives a Docker path: pull binshu/schemio:latest and run it with a volume mounted at /opt/schemio, port 4010 published, and FS_ROOT_PATH and SERVER_PORT set. A hosted version is available at schem.io.

How it compares

No paid products that Schemio replaces are named in the facts for this entry, and no other similar tools are named either, so it stands alone in this registry. Readers wanting a direct comparison should look at the project's own homepage and demo rather than expect a positioning statement here.

When to use it — and when not to

Choose Schemio when diagrams must be explored rather than printed, and when self-hosting on plain file-system storage is acceptable — the operator owns the storage directory, must back it up, and controls uploads through FILE_UPLOAD_MAX_SIZE (default 10485760 bytes). Skip it if prototyping is the main requirement, since the README states Schemio was not originally designed for that, and skip it if the team wants a fully managed service with a support agreement. The entry also carries 20 open issues and no listed release cadence beyond a last push on 2026-09-13, so evaluate maintenance activity before committing.

docker pull binshu/schemio:latest

docker run -v "$(pwd):/opt/schemio" \
    -p 4010:4010 \
    -e FS_ROOT_PATH=/opt/schemio \
    -e SERVER_PORT=4010 \
    binshu/schemio:latest