What Is NDJSON?
NDJSON (Newline-Delimited JSON) is a streaming format where each line is a valid JSON object. Unlike a JSON array, NDJSON can be processed line-by-line without loading the entire file into memory, making it ideal for big data and streaming pipelines.
NDJSON is used for:
- Log Processing: Each log entry is a separate JSON line.
- Streaming APIs: Sending real-time events as NDJSON chunks.
- Big Data: Loading data into Hadoop, Spark, and data warehouses.
- Data Export: Exporting database records as line-delimited JSON.
JSON Array vs. NDJSON
| Feature | JSON Array | NDJSON |
|---|---|---|
| Structure | Wrapped in [ ] brackets. | One JSON object per line. |
| Streaming | Must parse entire file. | Line-by-line streaming. |
| Memory Usage | Full file in memory. | One line at a time. |
| Standard | Yes, standard JSON. | De facto standard (jsonlines.org). |
| Primary Use | APIs, configs. | Logs, streaming, big data. |
How to Convert JSON to NDJSON Online
- Paste a JSON array: Enter an array of objects.
- Click Convert: Each array element becomes a single JSON line.
- Copy NDJSON: Use for streaming or log processing.
Frequently Asked Questions
What if my input is a single object, not an array?
The tool wraps single objects in an array automatically before conversion.
Can NDJSON contain nested objects?
Yes. Each line can be any valid JSON value, including deeply nested objects.
Is this tool safe?
Yes. Processing is 100% client-side.
Real-World Examples
NDJSON is used when exporting database records for Apache Spark processing, streaming real-time analytics events from server applications, collecting application logs in JSON format, and transferring data between microservices in big data pipelines.
Related Tools
- NDJSON to JSON — Convert NDJSON back to JSON array
- JSON to CSV — Convert JSON arrays to CSV