How to convert ndjson / json lines to csv
- Step 1Locate your NDJSON file — Common sources: Cloudflare logs, BigQuery exports, OpenAI fine-tune files, application log shipping.
- Step 2Drop the file on the converter — Auto-detect spots the line-delimited shape; force-pick NDJSON if detection fails.
- Step 3Leave flattening on — Nested fields like context.userId or geo.country become their own columns.
- Step 4Download the CSV — Open in Excel, paste into Sheets, or feed it to a downstream pipeline.
Frequently asked questions
Why won't Excel open my .ndjson file?+
Excel only opens .csv, .tsv, and its own formats out of the box. Convert to CSV here first, then double-click.
What happens with malformed lines?+
Conversion stops with the line number reported in the error. Fix the offending line in a text editor and re-run.
How big a file can the browser handle?+
Performance varies by device, but most modern laptops handle hundreds of thousands of lines comfortably. Free row limit applies for non-Pro accounts.
Privacy first
Conversion runs locally in your browser. No file is uploaded — only metadata counters are saved for signed-in dashboard stats.