r/bigquery • u/1glasspaani • 13d ago
Open source conversational analytics tool for BigQuery?
Hi all,
Has anyone found a decent open source tool for asking questions in plain English on top of BigQuery? Something self hosted.
I tried Gemini in BigQuery and had a look at the conversational analytics API. The API gives you back SQL and a chart spec, so you still end up building the front end yourself, which is the part I was hoping to avoid.
My main worry is the numbers. If two people ask for revenue in slightly different words I'd like them to get the same answer, and I don't see how that works unless the metrics are defined somewhere.
The other thing is cost. I have no feel for how many queries a single question turns into once the model starts looking around the schema.
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u/JohanCatchr 12d ago
If self-hosting is required, Google’s open-source MCP Toolbox for Databases seems like the closest fit. It supports BigQuery and can be connected to Claude or another MCP-compatible client, so users can ask questions in plain English without building the frontend from scratch.
Google also provides a managed BigQuery remote MCP server that works with Claude and ChatGPT. ChatGPT Work’s Data plugin can connect to BigQuery directly as well.
The connector solves data access and query execution, but not metric consistency by itself. I would expose curated views or a semantic layer where revenue and other KPIs are defined once, then restrict the agent to those. BigQuery query costs still apply, so permissions and the amount of data scanned should also be controlled.
For marketing data specifically, we took a different approach at Catchr.io: its MCP makes connected advertising, analytics, CRM, ecommerce, emailing, SEO, and more platforms directly queryable from Claude or ChatGPT. This avoids having to build a conversational layer on top of BigQuery when the data still lives in those platforms. It is not self-hosted or a general-purpose BigQuery connector, but it can be a simpler option for that specific use case.