Data file tools that run
in your browser

SmartQueryTools is a collection of browser-based data file tools powered by WebAssembly. Every operation runs entirely in your browser, on your device. No file is ever uploaded to a server. No account is required.

The engine processes CSV, Parquet, JSON, NDJSON, Excel, TSV, and Apache Arrow files with production-grade performance. That means you get a columnar query engine capable of handling millions of rows, vectorised operations, and efficient columnar reads — without leaving your browser tab.

All processing happens in a background Web Worker so the page stays responsive even when working with large files. Results are returned as downloadable files in whatever format you need: CSV, Parquet, JSON, Excel, SQL, Markdown, or HTML.

The tools cover the most common data file tasks: converting between formats, cleaning data (deduplication, whitespace trimming, null filling), reshaping (filtering, sorting, splitting, merging, transposing), and inspecting (viewing, validating, profiling). For more complex work, the SQL Query tool lets you write arbitrary DuckDB SQL against any combination of uploaded files.

SmartQueryTools is built for data analysts, data engineers, developers, and anyone who works regularly with structured data files. The most common use case is processing an export from a database, SaaS tool, or business application — converting it to a different format, cleaning it up, and loading it somewhere else — without needing to write a script or install software.

Supported formats include CSV, Parquet, JSON, NDJSON, Excel (XLSX), TSV, and Apache Arrow. Output formats also include SQL INSERT statements, Markdown tables, and HTML tables.