Cast Column Types in JSON Files Online

What types can I cast columns to in a JSON file?

VARCHAR (text), INTEGER, BIGINT, FLOAT, DOUBLE, BOOLEAN, DATE, and TIMESTAMP. The tool uses TRY_CAST for safe conversion — values that cannot be converted become null.

Can I cast multiple columns at once in a JSON file?

Yes. Set a target type for each column you want to change. Columns left as "Keep original" are passed through unchanged.

What happens to values that cannot be converted?

They become null. TRY_CAST never fails — it returns null for any value that does not fit the target type. Check the preview for unexpected nulls before downloading.

Is my data private?

Yes — completely. Your file is never uploaded to any server. Everything runs locally in your browser using WebAssembly — processing happens entirely inside your tab. Once you close the tab, nothing is retained.

What is the maximum file size?

The free limit is 50 MB. For larger files, performance depends on your device's available memory — most modern machines handle 500 MB to 1 GB comfortably.