100% local — no upload, no setup

Run SQL queries on CSV files directly in your browser

Use the full power of DuckDB SQL on your CSV data. No server, no setup, no installation.

Queryfiles.app gives you a complete SQL editor powered by DuckDB to query CSV, TSV and other delimited text files. SELECT, filter, aggregate and transform your data without leaving your browser.

Everything you need, nothing you don't

Full DuckDB SQL dialect

Use SELECT, WHERE, GROUP BY, HAVING, ORDER BY, CTEs, window functions and subqueries on your CSV data.

Auto schema inference

Column types are detected automatically so you can start writing SQL queries immediately after opening a file.

Private by design

Your CSV files never leave your machine. All processing happens locally in your browser.

How it works

  1. 1

    Open a file

    Drag and drop a Parquet, CSV, JSON or XLSX file onto the home page, or click Browse to select it from your computer.

  2. 2

    Schema detected instantly

    Queryfiles.app reads the file locally and automatically infers column names, data types and an initial SQL query.

  3. 3

    Query with SQL

    Edit the SQL in the built-in editor powered by DuckDB, run queries and explore your data in real time, all inside your browser.

Frequently asked questions

What SQL syntax does Queryfiles.app support?
Queryfiles.app uses DuckDB SQL, which is closely compatible with PostgreSQL syntax. It supports standard SQL, aggregation functions, window functions, CTEs (WITH clauses) and many built-in functions.
Can I use GROUP BY and aggregations on CSV data?
Yes. You can run SELECT column, COUNT(*), AVG(value) FROM data GROUP BY column and similar aggregation queries directly on your CSV files.
Can I JOIN multiple CSV files?
Currently Queryfiles.app supports one file at a time. Support for querying multiple files simultaneously is not yet available.
Do I need to know the schema before writing queries?
No. Queryfiles.app automatically detects column names and types. An initial SELECT * FROM data LIMIT 100 query is generated when you open a file.
Which SQL functions are available?
DuckDB supports a large set of built-in functions: string, numeric, date/time, JSON, regex, list and more. Refer to the DuckDB documentation for the full reference.

Ready to explore your data?

Drop a file and start querying in seconds. No account, no upload, no setup.

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