SQL Sandbox
Load local CSV or JSON files into an in-memory SQLite database and run SELECT queries without uploading data.
Query CSV and JSON files with SQL in your browser
Analysts and backend developers often receive ad hoc exports as CSV or JSON arrays. This
SQL sandbox loads those files into an in-memory SQLite database (via sql.js)
so you can run SELECT statements, filter with WHERE, sort with
ORDER BY, and limit rows without installing desktop tools or uploading data.
How to use the sandbox
- Start from the bundled employee sample or click Open CSV/JSON to load your file.
- Table names come from the sanitized filename (for example
sales_q1.csvbecomessales_q1). - Write a
SELECTquery and click Run query to preview rows in the table.
Need to format SQL text only? Use the SQL Formatter. To turn JSON into INSERT statements for MySQL, see JSON to MySQL.
Frequently Asked Questions
Which SQL statements work?
Read-only SELECT queries against tables you loaded. DDL and write statements (INSERT, UPDATE, DELETE) are blocked to keep the sandbox safe.
Can I join multiple files?
Yes. Load more than one CSV or JSON file, then reference each table name in a single SELECT with a JOIN clause.
Where is data processed?
Entirely in your browser. Files are read with the File API and stored in a local SQLite instance; nothing is sent to OnlineMiniTools servers.
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