Inkwell Data / File converter
Convert data files
CSV to Excel, Excel to CSV, JSON to CSV, CSV to Parquet, and every combination in between. Pick a file, pick a format, download.
How it works
Choose a CSV, TSV, Excel, JSON, JSON Lines or Parquet file. Inkwell Data reads it in your browser and shows a preview so you can check the columns came through correctly. Then pick an output format: CSV, TSV, Excel, JSON, JSON Lines, Parquet, SQL INSERT statements, a Markdown table or an HTML table.
For Excel workbooks with several sheets, you can choose which sheet to convert. Excel output comes with a bold, frozen header row, filters, and sensible column widths.
Questions
Are my files uploaded anywhere?
No. Your file is read by your own browser and processed on your device. There is no server receiving your data, no account, and nothing is stored after you close the tab.
How do I convert Excel to CSV without losing leading zeros?
Inkwell Data keeps every value as text while converting, so 00123 stays 00123. When writing JSON or Excel you can choose to detect numbers, and values with leading zeros are still kept as text.
Can I convert JSON to CSV?
Yes. Arrays of objects become rows, with one column per key. Nested objects and arrays are written as JSON text in their cell. JSON Lines (NDJSON) files work too.
What is Parquet and why convert to it?
Parquet is a compressed, columnar file format used by data warehouses and tools like Spark, Snowflake, BigQuery and pandas. Files are much smaller than CSV and keep column types. Inkwell Data can read and write it.
How big a file can I convert?
It depends on your device memory. Files with a few hundred thousand rows convert in seconds on a typical laptop. Very large files (over a few hundred MB) may be slow or run out of memory in the browser.
Why does my CSV look wrong in Excel?
Excel sometimes misreads UTF-8 accents. Tick "Excel-friendly CSV" before downloading, or convert straight to .xlsx instead.