LinkML editor web app

[adamlabadorf]

Hi,

I only recently learned about linkml and am already putting it in the center of several data modeling projects, it's great! I wasn't crazy about authoring linkml yaml by hand so I designed a web app that has an ERD style canvas for authoring schema. Here are the current features:

• Visual ERD canvas — drag, connect, and arrange LinkML classes and enums without touching YAML
• Properties panel — edit slot definitions, ranges, and constraints in a structured side panel
• Real-time YAML — live YAML preview with best-effort semantic round-trip preservation; recognized LinkML fields and unknown extras are preserved; formatting details (comments, blank lines, quoting style, YAML anchors, key ordering) are not
• Schema validation — structural checks including naming conventions (PascalCase classes/enums, snake_case slots), existence checks for is_a/mixin/range references, and inheritance cycle detection
• Focus mode — zero in on selected nodes and their direct relationships
• Git integration — clone, commit, push, and pull directly from the editor (browser OPFS or Electron fs)
• Multi-schema support — work with schemas that import other schemas; imported entities shown as read-only ghost nodes
• Dark & light themes — system-aware with manual toggle

I find it very useful myself, so I thought I'd share it with the community for feedback. It currently only supports a subset of the linkml metamodel, but if there is interest I'd be happy to take suggestions/pull requests for new features or bug fixes. It can run completely in-browser with local browser storage, but when deployed with a CORS git proxy (not available in the demo app) the github integration feature allows iteration of schemas hosted in github repos from anywhere without having to worry about specific logins for the app.

Full disclosure I had coding agents generate the code (which is why it looks so nice, I'm a python guy, not typescript developer), but I drove the design and architecture decisions myself, hopefully that's ok. There are sure to be some sharp edges in places.

GitHub: https://github.com/BU-Neuromics/linkml-modeler-app
Docs: https://bu-neuromics.github.io/linkml-modeler-app/
Demo app: https://bu-neuromics.github.io/linkml-modeler-app/app/

I saw @paulmillar 's discussion #3313 on using LinkML to drive data capture; this is upstream of that - schema authoring vs data entry - but the two concerns clearly meet somewhere.

Happy to demo at a future office hours if there is interest.

Thanks!

[matentzn]

Very cool! I agree YAML can be intimidating to some, but I'm not yet fully convinced that UML-style WYSIWYG editing is the right answer in every case. Schema editing is genuinely hard, and I don't think the final word has been written on how to do it well. Something closer to an ontology editor with a class hierarchy might actually be a better entry point for an editing workflow, with UML-style diagrams serving more as a way to explore (and perhaps edit) the connectivity between schema elements. Clearly no single solution will satisfy everyone.

[adamlabadorf]

Thanks! Yeah I came from the DBA world if that's not obvious. It was the connections between slots and classes that I really wanted to be able to visualize, as well as iterate quickly. I assume my tool will become less useful as the schema becomes more sophisticated, and I'm barely even a novice at LinkML at this point so I don't really understand what the end points are. Where do you think the UML approach will break down?

[adamlabadorf]

Yeah I see, this one isn't so bad, but I agree not very helpful from an authoring perspective. I did add a couple features to manage large schemas. First is sharding, where multiple schema can live in different files but can all refer to one another in the interface, then be merged later if required. This is how I am using it to model different parts of my data models and stay sane. The other is a focus mode, which isolates either selected nodes or based on subsets (which apparently doesn't work, bug I need to fix). The linkml metamodel was a good test! I think creating canvas views based on subsets rather than different files might be really helpful, I'll give that a shot. Thanks again for the feedback.

[matentzn]

We are contemplating a LinkML community workshop specifically so folks can demo their tooling and schemas later this year (maybe towards the end of fall). This would be a great forum to find like-minded folks. I am currently working with a group of great folks that use WYSIWYG UML editing for schemas (using Enterprise Architect) and they are looking for alternatives. Will point them to you as well.

[adamlabadorf]

That sounds great, I'd definitely be interested in attending a workshop. I submitted a poster to BOSC at ISMB, fingers crossed they accept it. Happy to work with others who are interested. Thanks!

[sandervd]

We are contemplating a LinkML community workshop specifically so folks can demo their tooling and schemas later this year (maybe towards the end of fall). This would be a great forum to find like-minded folks. I am currently working with a group of great folks that use WYSIWYG UML editing for schemas (using Enterprise Architect) and they are looking for alternatives. Will point them to you as well.

I work in the team using Enterprise Architect for editing. Our editorial team working on the data models is rather attached to having a visual representation. The two main arguments are:

• Collaboration with business users during workshops
• 'clean' UML diagrams, where the position of elements can be controlled, and the most important elements can be highlighted through the visual layout.

I did a little experiment recently in an attempt to address this issue, but I took a different approach:
LinkML drawio generator
The code is AI authored, so don't expect production code.

The code consists of two generators, allowing round-tripping:

• Generate a drawio model from a LinkML schema
• Annotate a LinkML schema with class positions and the position of connectors (class-valued slots)

I'm very interested in all the different approaches people take...

[adamlabadorf]

Very cool, I like how it uses drawio, that makes it very accessible. Based on @matentzn comments on large schemas I implemented a bunch of new features to help with that, including Named Views and Subsets, that allow for creating canvases with subsets of classes that each have independent persistent layout coordinates. There's also a new Display Panel with a bunch of controls for canvas display properties and interaction.

[Benja1972]

Quite nice initiative! I came across here searching the visual app for LinkML schema after I saw that Concerto released their playground https://concerto.accordproject.org/ . I prefer LinkML for more richer expressiveness and tooling ecosystem.

[adamlabadorf]

Thanks! Let me know if you find it useful or have suggestions on improvements. I hadn't heard of concerto, but their playground looks nice and it has some ideas I might add.