qsv is a free, open-source data-wrangling toolkit that gives Claude the ability to work directly with data files on your computer — CSV, Excel, JSONL, Parquet, and more with blazing speed. It offers hundreds of built-in functions for data transformation, analysis, and validation, but typically requires being comfortable with command-line tools.
Note
Q: Why do I need the qsv MCP Server or the Claude Cowork plugin? Don't AI chatbots already handle data?
See #3701
With the qsv MCP Server and Claude Cowork plugin, you can use all of qsv's power through natural language commands in your AI agent — no programming required. Just ask it to analyze, clean, transform, or visualize your data files, and it will translate your requests into qsv commands behind the scenes.
No uploads, no file size limits, no data leaving your machine.
No programming experience required. Just follow the steps in order.
- Claude Desktop — download here
- About 5 minutes of your time
The qsv MCP Server lets Claude read, analyze, and transform your local data files in place — only uploading statistical metadata to Claude to inform its operations. This section shows how to install and use it in Claude Desktop Chat and Claude Cowork; the same server also works with Claude Code and Gemini CLI via a separate build-from-source flow described below.
No manual binary install needed. The MCPB bundle automatically downloads and installs the qsv binary (qsvmcp) for you.
Go to: https://github.com/dathere/qsv/releases/latest
Download the .mcpb file and save it to your Downloads folder.
- Double-click the downloaded
.mcpbfile. This should open Claude Desktop. - Click "Install". A Confirmation dialog will appear confirming the installation. Click "Install" again to proceed.
- That's it! The MCP Server is now installed and running in the background.
After installation, you can customize the MCP Server settings in Claude Desktop > Settings > Extensions > qsv. The defaults work for most users, but here are some key settings you might want to adjust:
-
Working Directory — where Claude looks for your data files by default.
- macOS:
$HOME/Downloads - Windows:
%USERPROFILE%\Downloads
- macOS:
-
Allowed Directories — folders Claude is allowed to access (for security).
- macOS:
$HOME/Downloads:$HOME/Documents(use:to separate folders) - Windows:
%USERPROFILE%\Downloads;%USERPROFILE%\Documents(use;to separate folders)
- macOS:
-
qsv Binary Path — usually auto-detected. If not found, the installer will prompt you to download it.
Close and reopen Claude Desktop. Then start a new conversation and ask:
"List data files in my Downloads folder"
If Claude shows you a list of files, the qsv MCP Server is working.
The Cowork plugin adds a workflow layer on top of the MCP Server, giving Claude Cowork sessions access to domain skills and specialized subagents for guided data workflows.
Cowork requires a Claude Pro plan (or higher). See plans and pricing.
Prerequisites: The qsv MCP Server must be installed first (Step 1)
- Click your profile icon (bottom-left) > Settings
- Click on Capabilities -> Skills -> Go to Customize
- Go to Personal plugins and click on the + sign
- Select "Add marketplace" from the list
- A dialog will appear. Enter
dathere/qsvand click "Synch" - You will be on the Customize panel again. Click the + sign next to "Personal plugins" and select "Browse plugins"
- In the Browse Plugins dialog, click on the Personal tab and select the "qsv" plugin.
- Click "Install" on the "Qsv-data-wrangling" plugin
- Start a new Cowork session in Claude Desktop
- Check the Context panel — the qsv skills should appear
- Try invoking a skill like
/data-profileto confirm everything works
| Component | Details |
|---|---|
| 9 user-invocable skills | /csv-query, /data-clean, /data-convert, /data-describe, /data-join, /data-profile, /data-validate, /data-viz, /infer-ontology |
| 6 model-invoked skills | bls-query, csv-wrangling, data-quality, genai-disclaimer, qsv-performance, reproducible-analysis |
| 3 subagents | data-analyst, data-wrangler, policy-analyst |
The qsv MCP Server also works with CLI-based tools:
- Claude Code — Full setup guide: CLAUDE_CODE.md
- Gemini CLI — Full setup guide: GEMINI_CLI.md
Both require building the MCP server from source (npm install && npm run build in .claude/skills/).
Once the core setup is complete, you can add more MCP servers to give Claude access to external data:
| Server | What it provides |
|---|---|
| US Census Bureau | Population, demographics, economics — via a local Docker container |
| Wikidata | The free, structured knowledge graph maintained by the Wikimedia Foundation |
| FBI Crime Data | Crime statistics, arrests, hate crimes, NIBRS incidents, law enforcement data |
See ADDITIONAL_SERVERS.md for installation instructions.
| Problem | Solution |
|---|---|
| "qsv binary not found" | The MCPB installer should auto-install qsvmcp. Check Settings > Extensions > qsv to verify the binary path. If needed, download manually: macOS | Windows. |
| Claude says it can't find your file | Use the full file path (e.g., /Users/you/Downloads/data.csv or C:\Users\you\Downloads\data.csv) or ask Claude to "list data files" first. |
| Extension not appearing | Restart Claude Desktop completely. Check Settings > Extensions for "qsv Data Wrangling". If missing, reinstall the .mcpb file. |
| "qsv command not found" | Use qsv_config in a Claude chat to see diagnostics. Try setting the binary path manually in Settings > Extensions > qsv. |
| Large file timeouts | Increase the command timeout in Settings > Extensions > qsv > Advanced Settings. Pre-index large files by asking Claude to "index large-file.csv". |
| macOS: "Operation not permitted" running qsv | Run xattr -d com.apple.quarantine $(which qsvmcp) in Terminal to clear the quarantine flag. |
| macOS: "Permission denied" | Try prefixing with sudo. You may also need to allow the app in System Settings > Privacy & Security. |
| Config file won't save | Make sure Claude Desktop is closed while editing the config file. |
| Problem | Solution |
|---|---|
| Cowork not available | Claude Cowork requires at least a Claude Pro subscription. |
| Marketplace add fails | Check your internet connection and that you can access github.com/dathere/qsv. |
| Skills don't appear as slash commands | Start a new Cowork session after installation. Existing sessions won't pick up the plugin. |
| Skills not showing in Context panel | Restart Claude Desktop and start a fresh Cowork session. |
| Plugin not updating | Go to Settings -> Capabilities -> Skills -> Go to Customize -> Personal plugins -> + sign -> Browse plugins and click on the "qsv" plugin to manually check for updates. |
- Add more data sources — Install the US Census Bureau, Wikidata, and FBI Crime Data MCP servers: ADDITIONAL_SERVERS.md
- Learn about file access — Supported formats, security, and configuration: FILESYSTEM_USAGE.md
- Full technical reference — Desktop Extension Reference | MCP Server README
- All qsv commands — github.com/dathere/qsv
Local file analysis:
"Show me statistics for sales.csv in my Downloads folder"
SQL queries:
"Run a SQL query on orders.csv to find the top 10 customers by total spend"
Cowork with the plugin:
"/data-profile my latest CSV file, then /data-clean it based on the quality issues you find"
Combining data sources:
"Look up the Wikidata entities for all US state capitals, then pull their Census population data and save the results as a CSV"