Building Semantic Models Without Power BI Desktop: What the Browser Can Do Now

In Short: You Can Now Edit a Power BI Semantic Model in the Browser

For most of Power BI's life, serious modelling meant Power BI Desktop, and Desktop meant Windows. That is no longer the whole story. Between August and September 2026 Microsoft filled in most of the remaining pieces, and you can now edit a Power BI semantic model in the browser in four ways:

• Web modelling in the Power BI service, for relationships, DAX, security roles and Power Query
• DirectQuery and composite models on the web, announced in the September 2026 feature summary
• TMDL view on the web (preview), a code editor for the whole model
• The hosted Power BI Authoring MCP server (preview), which lets an AI agent edit models in a workspace with nothing installed

This post covers what each does, the limits Microsoft documents, and where Desktop still wins. For the wider comparison, see Power BI Desktop vs the Power BI service.

Web Modelling: The Everyday Editor

Open a semantic model from the workspace, the OneLake catalog or a report in edit mode, and it opens in Viewing mode so nobody changes anything by accident. Switch to Editing mode and you can:

• Create measures, calculated columns and calculated tables, with IntelliSense
• Create and edit relationships, mark a date table and build diagram layouts
• Get data and transform it in Power Query, for Import and DirectQuery tables
• Define row-level security roles, including DAX rules, and assign members
• Refresh schema, data or both, for the model or one table

Several people can work on the same model at once. You need write permission on the model, and only the model owner can use Get data to add import tables. Admins can turn web editing on or off for the organisation or for security groups, and every change is logged in the audit log.

There is no undo. Changes save automatically and are permanent. Microsoft's safety net is semantic model version history, which lets you restore an earlier version. Make sure your team knows it exists before they start, not after.

DirectQuery and Composite Models on the Web

Until September, web modelling was effectively an Import story. The September 2026 summary adds the ability to create and edit DirectQuery semantic models in the service: connect to a source, choose DirectQuery, then manage relationships, write DAX and switch individual tables to Import or Dual. That last step means composite models are now possible in the browser too.

Microsoft's post calls out Mac, Linux and Windows users explicitly. It does not attach a preview label to this one, so check what you see in your tenant before you plan around it.

TMDL View on the Web: The Model as Code

TMDL view has been generally available in Desktop since September 2025. Since August 2026 it is in preview in the browser. Drag any table, measure or the whole model into the editor and you get its full definition as TMDL, including properties the normal interface hides, such as partition definitions.

It is the fastest way we know to do bulk work: rename a prefix across a hundred tables with find and replace, put every sales measure in one display folder, or paste in a calendar table from another model. Before anything is applied, a preview shows a before-and-after diff of the model.

It differs from Desktop in ways that matter:

• View mode and Edit mode. You script and preview in View mode and only apply in Edit mode.
• Scripts are not kept. Close the model or the browser and your script tabs are gone. Keep anything reusable in source control.
• Version history is built in. File, then Save to version history captures a restore point before a risky change.
• Write permission on the model is required.

TMDL view on the web is also, for now, where some new engine features are configured. Full-text and string indexing are set through TMDL on the web or XMLA during their preview - see our post on full-text search and the other new DAX functions.

The Hosted Authoring MCP Server: Agents Without a Local Install

We covered the local server when it was the Power BI Modeling MCP server. The September release adds a hosted (preview) endpoint, run by Microsoft, at https://api.fabric.microsoft.com/v1/mcp/powerbi/authoring. An agent in GitHub Copilot or another MCP client can create and change tables, measures, relationships, calculation groups and security roles in a workspace model, signed in as you. Microsoft notes this unblocks Mac users, because the local server does not support macOS.

The trade-offs, from Microsoft's comparison:

• Hosted: nothing to install, Entra ID as the signed-in user, workspace models only. No transactions, no traces, no access to Desktop or files on disk. Your admin must enable the tenant setting "Users can use the Power BI Model Context Protocol server endpoint".
• Local (generally available): works against Desktop and PBIP or TMDL files, supports service principals for CI pipelines, transactions and traces.
• Both: DAX queries are capped at 100,000 rows, and the agent needs write permission to change anything (Build permission only lets it query).

Microsoft's own advice is to back up the model first and to work in PBIP files under Git where you can, so every agent change is a diff you review. With the hosted server there is no local file, so version history becomes your review point. That is a reason to keep hosted agent edits in development workspaces.

What Still Needs Desktop

Microsoft's list of gaps in web modelling is short but real:

• The View as dialog for testing security roles
• Q&A setup, including synonyms (which matters less now that Q&A is retiring)
• Feature tables, the barcode data category and report sensitivity classification
• Models with live connections or automatic aggregations cannot be opened
• Power Query is not available for Direct Lake tables or for models with incremental refresh
• Models deployed through deployment pipelines can only be edited in the development workspace

Renaming a field on the web also does not update visuals in downstream reports. Do renames before reports are built, or expect to fix them.

How We Would Use Each Tool

• Small fixes and Mac colleagues: web modelling, in development workspaces
• Bulk or repetitive changes: TMDL view on the web, with a version saved first
• Agent-assisted builds on workspace models: the hosted MCP server, in development only
• Main development, performance work and anything under Git: Desktop with PBIP, or the local MCP server

One small extra: the semantic model settings pane is becoming the default in the service (preview, rolling out gradually), so settings open beside your workspace rather than on a separate page. For more on how these tools are changing our delivery, see how FabCon 2026 changes the way we build Power BI projects.

Where Solv Systems Comes In

The browser is now a real place to build semantic models. The risk is that changes made there skip review. Our Power BI consulting team can set up a workflow that uses the browser, Desktop and agents where each fits, with development workspaces, version history and Git keeping production safe.

Sources and Further Reading

• Edit semantic models in the Power BI service
• Use TMDL view in Power BI
• TMDL View on the web: Edit semantic models as code in your browser (Preview)
• Power BI Authoring MCP server
• Power BI September 2026 Feature Summary
• Manage semantic model settings in context with the default settings pane (Preview)