Kusto Workbench

A modern, notebook-like workflow for Kusto Query Language (KQL) in VS Code.

Kusto Workbench is built for the tight loop of writing queries, running them, inspecting results, and iterating quickly; without forcing you to abandon existing .kql / .csl files. It uses the official Microsoft Kusto editor (GitHub) so you will always have a reliable and robust Kusto editing experience and you'll get extra goodies on top that you won't get in the official clients (web or desktop).

It has many power features that accelerate the experts, and empower the newbies. You can search and view results, including complex JSON columns. You can transform data without changing queries. You can create charts and graphs with just a few clicks. You can compare two queries in terms of performance and results to make performance improvements with confidence. All this is just scratching the surface as there is so much more for you to be pleasantly surprised by.

Copilot integration gives your favorite LLM the right context and tools to actually write smart Kusto queries, the type of Kusto queries an expert would write. It can execute its own queries and perform its own checks before giving you a response, drastically improving the quality of the response.

It has advanced markdown capabilities (thanks to the amazing folks at TOAST UI), so you could even just use it as a better markdown editor (with WYSIWYG support) for VS Code. Open existing .md files (open with, or change association), or make a new empty .mdx file and give it a go.

Walkthroughs

New to the extension? Two built-in walkthroughs will get you going fast:

• Agent-First Workflow – Let the VS Code Copilot agent build queries, charts, and full reports for you.
• Editor-First Workflow – Write KQL yourself, explore results, then add charts and markdown around them.

Open them from the command palette (Kusto Workbench: Open Walkthroughs...) or from the Activity Bar.

Key Features

It is not really possible to cover every single feature here with a screenshot and an explanation. Hopefully most of the functionality is intuitive, and easy to discover organically. If you are lacking any functionality or you think something isn't working correctly, just please don't hesitate to reach out, I will get it done for you!

Activity Bar

Click the icon in the Activity Bar for a bunch of helpful shortcuts.

All of this is also available through the VS Code command palette, so if you prefer a more minimal look, you can turn off the Activity Bar icon in the extension's settings.

Import connections

Don't manually add every single Kusto cluster and database you work with. If you have been using Kusto either on the desktop or browser already, just import your existing connections.

1. In Kusto Explorer, export your saved connections as an XML file (commonly named connections.xml).
2. In VS Code, open the query editor and choose Import from .xml file… in the connection picker.

Save connections to favorites

Save frequently used connections to favorites, with a friendly name so you can remind yourself what the connection is used for.

VS Code custom agent that actually works

Just let the custom VS Code agent 'Kusto Workbench' do all your work. It's crazy how good this thing is. If you are having problems, make sure you have a really good model like Claude Opus 4.6 selected. If it still doesn't work, report the issue and I'll fix it for you. I use this every day, if it doesn't work for you, just tell me!

The agent can:

• Create and configure query, markdown, chart, transformation, and Python sections
• Execute queries and inspect results
• Search across all your cached schemas to find tables and columns
• Fetch schemas live from clusters it hasn't seen before
• Orchestrate multi-section reports end to end
• Use a dedicated sub-agent for deep Kusto data searches

Integrated Copilot Chat (per section)

Each Kusto query section has its own Copilot Chat window built right in. Click the Copilot button in the query toolbar to open it. The LLM knows your database schema, can execute queries to validate its suggestions, and has full conversation history so you can iterate naturally. You manage the conversation history directly in the UI, remove stale tool calls, clear the whole chat, or just keep going. Use this when working inside a very specific section of the overall workbook, to make surgical changes, not to build a new workbook from scratch; use the custom Kusto Workbench agent via the VS Code chat window for that instead.

Modern Kusto editor using the official bits from Microsoft

Uses the official Microsoft Kusto editor (GitHub) so you will always have a reliable and robust Kusto editing experience and you'll get extra goodies on top that you won't get in the official clients (web or desktop).

Load .csv data directly from the internet

If you have a URL, then you can load it.

Transform data

You can transform Kusto query results without changing the query itself. Derive new columns, summarize and aggregate, get distinct values, or pivot your data and all without writing another line of KQL. Transformations also work on .csv files loaded via a URL section.

Chart data

Create charts from Kusto query results or .csv data. Supports line, area, bar, scatter, pie, and funnel chart types. Configure axes, legends, data labels, and more. Charts update live when you re-run your query.

Prettify query

Use the query toolbar "Prettify" action to apply Kusto-aware formatting rules (for example, improving layout around common operators such as where and summarize).

Diagnostics and debugging

When a query fails, Kusto Workbench surfaces helpful, human-friendly diagnostics:

• Go-to-line behavior to take you straight to the relevant part of the query
• Highlighting of important terms to focus your attention with red squiggles
• Hints in the scrollbar

Query comparison and performance optimization

If you have an existing query that you want to improve without changing its behavior and the results it returns, you can use the built-in functionality to compare its performance and to guarantee that the data returned is identical, even if the rows and columns might be out of order.

Now with server-side stats too! Performance statistics from the Kusto cluster itself are surfaced on hover over the results label, and automatically when comparing queries.

Share to Teams and Azure Data Explorer

Share a query as an Azure Data Explorer link with a single click. When sharing entire sections, the content pastes nicely into Teams and other rich editors.

Multi-account support

Sometimes we need to authenticate to different Kusto clusters with different identities, and this extension not only supports this scenario, but allows it even within a single file.

Connection Manager and Cluster Explorer

Explore the Kusto clusters you have added connections to with ease. Browse the tables, functions and their definitions. Create new .kqlx files with the connection details for a database already prefilled, ready to go.

Leave No Trace

Are you connecting to a Kusto cluster for which you should never export data or save data locally due to access restrictions, legal requirements, etc? Just flag the cluster and the extension will never save any of its data to disk, or even in temporary files. It will still allow you to save the queries and the chart settings, but the data itself will have to be retrieved each time you connect to the cluster.

Markdown sections

Full WYSIWYG and raw markdown editing powered by TOAST UI Editor. Add narrative text, documentation, and headings around your queries and charts to build complete reports.

Cell Value Viewer

Double-click any cell in the results table to open its contents in a dedicated viewer with search capabilities. Works great for long strings, JSON, and any value that doesn't fit comfortably in a table cell.

Search results

Search within query results using simple wildcards or full regex.

Open Remote Files

Open .kqlx files directly from GitHub or SharePoint using sharing or raw URLs. No need to download first.

Development Notes

The Copilot agent can store development notes per file (corrections, schema hints, gotchas) that persist across sessions and improve AI-assisted workflows over time. View them with Kusto Workbench: Show Development Notes.

Python sections

Embed Python code cells alongside your KQL. Python runs locally on your machine, and output is captured inline. Great for post-processing query results or running custom analysis.

Quick start

1. Open the Command Palette (Ctrl+Shift+P).
2. Run Kusto Workbench: Open Query Editor.
3. Add a connection, pick a database, and run a query.

Keyboard shortcut: Ctrl+Shift+Alt+K (Cmd+Shift+Alt+K on macOS) opens the Query Editor directly.

To open a file:

• .kql / .csl: open it normally (opens in compatibility mode)
• .kqlx: create an empty file and open it normally, or run Kusto Workbench: Open .kqlx File
• .mdx: create an empty file and open it normally

File formats (and "no file" mode)

Open existing .kql and .csl files

You can open existing .kql and .csl files with no conversion. The file stays plain text, and saving writes back plain text. If you add more stuff to these types of files, you are asked to save a .json file with the same filename side-by-side.

Create .kqlx files for convenience

Use .kqlx and .mdx files to keep everything in a single file (.kql and .csl files require a sidecar .json file for some of the functionality).

"No file" mode (persistent global session)

You don't need to create a file to use the extension. Run Kusto Workbench: Open Query Editor and the extension opens a global, persistent session that auto-saves to a .kqlx file stored in VS Code's global storage. This session is designed to survive VS Code restarts. If you want to turn that session into a real file in your workspace later, use Kusto Workbench: Save Session As... (.kqlx).

Open Remote File

You can open files directly from GitHub or SharePoint using sharing or raw URLs using Kusto Workbench: Open Remote File from the command palette or from the Quick Access panel off the Activity Bar icon.

Commands

Command	Description
Kusto Workbench: Open Query Editor	Open the global persistent session
Kusto Workbench: Open Remote File	Open a .kqlx file from a GitHub or SharePoint URL
Kusto Workbench: Open .kqlx File	Create or open a .kqlx notebook
Kusto Workbench: Open .mdx File	Create or open an .mdx notebook
Kusto Workbench: Save Session As... (.kqlx)	Save the current session to a file
Kusto Workbench: Manage Connections	Open the Connection Manager
Kusto Workbench: Delete All Connections	Remove all saved connections
Kusto Workbench: Show Cached Values	Inspect cached auth tokens, databases, etc.
Kusto Workbench: Reset Copilot Model Selection	Reset the sticky model choice for integrated Copilot Chat
Kusto Workbench: Open Walkthroughs...	Launch the built-in guided walkthroughs
Kusto Workbench: Open Kusto Workbench Custom Agent	Open the Copilot Chat panel with the Kusto Workbench agent
Kusto Workbench: Show Development Notes	View AI development notes stored in the current file

Requirements

• VS Code 1.107.0 or higher
• For Python sections: a local Python install available as python, python3, or py on your PATH

Data & privacy (how it actually works)

This extension is designed to keep your work local by default, and only sends data to remote services when you explicitly run an action (run a query, optimize with Copilot, etc.).

What gets stored locally

• Connections: Saved in VS Code extension global state on your machine (name + cluster URL + optional default database). This is not synced by the extension itself, but your VS Code settings/profile sync behavior may vary.
• Authentication account preferences (per cluster): The extension remembers which Microsoft work account was last used successfully per Kusto cluster (account id/label only). This helps avoid repeated sign-in prompts when you use multiple clusters that require different accounts.
• .kqlx notebooks: Stored wherever you save them (workspace file), and contain your section content (queries, markdown text, python code/output, URL section settings, etc.).
• Persistent "no file" session: If you use Kusto Workbench: Open Query Editor, the session auto-saves to a .kqlx file in VS Code's global storage for this extension so it can survive restarts.
• Optional persisted query results: When enabled/available, the extension may embed recent query results into the .kqlx state as JSON (capped at ~200KB per section). If you save a .kqlx, those embedded results become part of the file.
• Schema cache: Database schemas are cached on disk (in the extension's global storage) to speed up iteration. The cache is versioned and automatically invalidated when the format changes.
• Development notes: AI-generated development notes are stored within the .kqlx file alongside your sections.

What gets sent to your Kusto cluster

When you click Run (or any action that executes KQL), the extension sends:

• Your query text
• The target cluster and database
• Your Microsoft access token (obtained via VS Code's built-in Microsoft authentication)

The extension uses vscode.authentication.getSession('microsoft', ['https://kusto.kusto.windows.net/.default'], …) to acquire a token. Token lifecycle and secure storage are handled by VS Code; the extension uses the token in memory to authenticate requests.

If you work with multiple clusters that require different accounts, the extension will try previously-used accounts silently (without prompting) and will only prompt you to sign in when none of the known accounts work for the target cluster.

What gets sent to GitHub Copilot

When you use Optimize query performance or the integrated Copilot Chat:

• The extension sends the prompt (which includes your query text and database schema) to GitHub Copilot via VS Code's Language Model API (vscode.lm).
• The extension does not send your Kusto credentials to Copilot.
• Any result comparison happens by running queries against your Kusto cluster (not by executing anything inside Copilot).

Important note: the prompt can be edited in the UI; anything you include there is part of what gets sent to Copilot.

Python sections

Python sections run locally on your machine by spawning a local Python interpreter (python, python3, or py).

• Your code is executed locally.
• Output is captured (with size limits) and may be stored in the .kqlx file if you save.

Diagnostics and logs

• Query errors returned by the Kusto SDK/cluster may be surfaced in the UI (and may include fragments of your query or server-provided diagnostics).
• The extension may write diagnostic information to the VS Code Developer Tools console during development/troubleshooting.

How to remove stored data

• Remove saved connections: use Kusto Workbench: Manage Connections.
• Remove .kqlx content (including embedded results): delete or edit the .kqlx file.
• Clear the persistent session: delete the extension's global storage for Kusto Workbench (this removes the auto-saved session file).

Third-party credits

This extension is built on top of some fantastic open-source projects. Huge thanks to the teams and individuals behind them:

Component	License	Maintainer	Link
Monaco Editor	MIT	Microsoft	github.com/microsoft/monaco-editor
Monaco Kusto	MIT	Microsoft / Azure	github.com/Azure/monaco-kusto
Azure Kusto Data SDK	MIT	Microsoft / Azure	github.com/Azure/azure-kusto-node
Azure Kusto Ingest SDK	MIT	Microsoft / Azure	github.com/Azure/azure-kusto-node
Azure Identity	MIT	Microsoft / Azure	github.com/Azure/azure-sdk-for-js
TOAST UI Editor	MIT	NHN Cloud FE Development Lab	github.com/nhn/tui.editor
TOAST UI Editor Color Syntax Plugin	MIT	NHN Cloud FE Development Lab	github.com/nhn/tui.editor
Apache ECharts	Apache 2.0	Apache Software Foundation	github.com/apache/echarts
marked	MIT	marked contributors	github.com/markedjs/marked
DOMPurify	Apache 2.0 / MPL 2.0	Cure53	github.com/cure53/DOMPurify
esbuild	MIT	Evan Wallace	github.com/evanw/esbuild

License

MIT