datacharter 0.3.0

Charter your data — contract-governed local data exploration, powered by DuckDB

DataCharter

Explore all your data locally, in one place — contract-governed data exploration, powered by DuckDB

Contract-governed local data exploration, powered by DuckDB. Define your sources as data contracts (ODCS-compatible YAML), query them through DuckDB's SQL federation engine with real source pushdowns, and explore in a local web UI — SQL editor with live preview, auto-charts, profiling. Every answer shows which source columns it read; ask questions in plain language or serve the whole thing to an AI agent over MCP, with PII masked from the model — all on your machine.

Status: pre-release. V1 in development.

Quick start

# Try it instantly on generated demo data — no config, nothing to install globally:
uvx datacharter serve
# → opens a local workspace on http://127.0.0.1:8321

# Or install it:
pip install datacharter

# Start a real workspace:
datacharter init            # scaffolds charter.yaml, queries/, .env.example
datacharter serve           # explore in your browser

# Natural-language agent — bring your own endpoint…
export OPENAI_BASE_URL=...  # any OpenAI-compatible API
export OPENAI_API_KEY=...
datacharter serve
# …or run fully local (no API key, no data leaves your machine):
datacharter serve --local   # uses Ollama (qwen3:8b by default)

Drop a CSV, Parquet, or JSON file onto the window to query it instantly.

Why

• Your contracts are the catalog. charter.yaml describes sources, tables, and PII fields — the same contract spec your data team already writes.
• One engine, every source. Postgres, MySQL, SQLite, BigQuery, SQL Server, S3/GCS/Azure files, Iceberg, Delta — federated joins across all of them, with filters and projections pushed down where the data lives — even across a cross-source join, each leg is filtered at its source. Snowflake is supported via connector extract (datacharter[snowflake]) with filters/projections pushed into the extract. Every source's tables are exposed under one flat source__table naming scheme.
• Local-first. One process, your machine, no cloud dependency. Optional --local agent mode runs a small open model via Ollama — no API key, no data leaves your machine.
• The workspace is a directory. charter.yaml + queries/*.sql + .env.example — commit it, clone it, datacharter serve. Your team's whole exploration environment travels as a repo; secrets and local state never do.

More than a viewer

DataCharter governs and audits your data, not just displays it — see the CLI reference for the full command set:

• Governed MCP server — datacharter mcp exposes read-only, PII-masked query tools to any MCP client (Cursor, Cline, or your own agent).
• Contracts you can check — datacharter drift exits non-zero when a declared table or PII column disappears; datacharter scan detects PII columns to add.
• Answers that show their work — every result reports the source columns it read; datacharter diff compares relations across sources; datacharter metric runs governed metric definitions.
• Privacy-first — serve --offline runs with no outbound network, and the model never sees raw PII (flip Agent view in the UI to see exactly what it does).

Built on

DataCharter stands on excellent open-source foundations:

• DuckDB — the analytical engine at our core: federation (ATTACH), file formats, Iceberg/Delta, encryption, autocomplete.
• Open Data Contract Standard / datacontract.com — the contract format charter.yaml speaks.
• Model Context Protocol — the open protocol the datacharter mcp server speaks to agents and MCP clients.
• Vega-Lite — declarative charting.
• Monaco Editor — the SQL editor.
• TanStack Table & Virtual — the virtualized results grid.
• And the Python & React ecosystems — FastAPI, pydantic, httpx, keyring, and ruamel.yaml on the backend; React and Vite on the front.

Testing uses VidaiMock, an Apache-2.0 mock LLM server, as the offline agent endpoint in CI.

DuckDB is a trademark of the DuckDB Foundation. DataCharter is an independent project and is not affiliated with or endorsed by the DuckDB Foundation.

License

Apache-2.0