100% local — files never leave your device
Convert NDJSON to TopoJSON
Turn GeoJSON Lines (NDJSON) into TopoJSON instantly in your browser. No upload, no account, and no file ever crosses the network.
About GeoJSON Lines (NDJSON)
One GeoJSON feature per line. Streams well into BigQuery, DuckDB and Athena.
About TopoJSON
Quantized topology used by D3 and web cartography.
- Export quantizes coordinates and writes one arc per ring; arcs are not deduplicated.
Step by step
How to convert NDJSON to TopoJSON
- 01
Drop your .ndjson file
Open the converter and drop the GeoJSON Lines (NDJSON) file — parsing happens locally in a Web Worker, so nothing is uploaded.
- 02
Choose TopoJSON as the output
Pick TopoJSON, reproject to any of 180+ coordinate systems if needed, trim attributes and preview the geometry on a map.
- 03
Download the .topojson file
Save a single file, or convert a whole batch and download everything as a ZIP. Nothing is stored after the download.
NDJSON to TopoJSON — questions
Is converting NDJSON to TopoJSON really private?
Yes. The conversion runs entirely in your browser using a Web Worker — the GeoJSON Lines (NDJSON) file is never sent to a server, so it works with confidential data and offline.
Do I need an account to convert NDJSON to TopoJSON?
No. There is no signup, no email and no install. Open the converter, drop the file and download the result.
What happens to attributes and coordinate systems?
Export quantizes coordinates and writes one arc per ring; arcs are not deduplicated. You can also reproject between 180+ coordinate reference systems or add a custom proj4 definition before writing.
Need the other direction? Convert TopoJSON to NDJSON