Utilora

SQL File Explorer — Query CSV, Parquet & JSONL

Data Tools

What is SQL File Explorer — Query CSV, Parquet & JSONL?

SQL Explorer runs full SQL queries against local files entirely in your browser using DuckDB WASM. You can upload CSV, Parquet, or JSONL files and query them using standard SQL — no database server, no upload to a remote service. DuckDB is an embedded analytical database designed for fast columnar analytics, making it surprisingly capable for a browser-based tool. It handles complex queries including joins across multiple files, window functions, aggregations, and nested data structures.

How it works

DuckDB WASM loads into a Web Worker. When you upload a file, DuckDB registers it as a virtual table (read_csv_auto, read_parquet, read_json). Your SQL query is executed against DuckDB's in-memory engine. Results are streamed back and displayed in a table, with the option to export as CSV.

Features & Benefits

  • Full SQL on local files — SELECT, WHERE, GROUP BY, JOINs, window functions
  • Supports CSV (auto-detected), Parquet, JSONL, and JSON files
  • Powered by DuckDB WASM — the same engine used in production data pipelines
  • Your data never leaves your browser — runs entirely client-side

Frequently Asked Questions

What SQL dialect is supported?

DuckDB SQL — a superset of standard SQL with analytical extensions including window functions, UNNEST, LIST functions, and more. See duckdb.org for the full reference.

How large a file can it handle?

DuckDB WASM handles files up to several hundred MB comfortably in modern browsers. Performance depends on available RAM and the complexity of your query.

Is my data uploaded anywhere?

No. DuckDB runs entirely in a Web Worker in your browser via WebAssembly. The WASM binary (~7MB) is downloaded once from a CDN and cached; your data files never leave your device.

Can I query multiple files?

Yes. Upload multiple files and reference them by name in SQL. For example: SELECT a.*, b.name FROM read_csv_auto('orders.csv') a JOIN read_csv_auto('customers.csv') b ON a.customer_id = b.id

What happened to Vortex file support?

Vortex (SpiralDB's columnar format) is not yet supported by DuckDB WASM. We'll add it when a stable DuckDB extension ships.

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