What is NDJSON and how does it differ from JSON?

NDJSON (newline-delimited JSON) puts one complete JSON object on each line with no enclosing array and no commas between objects. A standard JSON file is a single array or object. NDJSON is streamable — tools read it one line at a time.

Why do BigQuery and Elasticsearch want NDJSON?

Both ingest data line by line for memory-efficient streaming. BigQuery's NEWLINE_DELIMITED_JSON source format and the Elasticsearch _bulk API both expect one JSON document per line rather than a wrapping array.

What does type inference do?

With it on, a cell like 42 becomes the number 42, true/false become booleans, and null becomes JSON null. Values such as 007 or 1,000 stay strings so identifiers are not corrupted. Turn it off to keep every cell as a quoted string.

Does my CSV get uploaded anywhere?

No. Parsing, conversion, and download all happen in your browser using the File and Blob APIs. Nothing is sent to a server or stored.

CSV to NDJSON Converter

Convert CSV into newline-delimited JSON

The CSV to NDJSON Converter turns each CSV row into a single JSON object on its own line. This newline-delimited format — also called JSON Lines or JSONL — is what BigQuery loads, the Elasticsearch bulk API, and most log shippers expect, because it can be read and written one record at a time without holding the whole file in memory.

How it works

The tool parses your CSV with a quote-aware parser, so commas, newlines, and escaped quotes ("") inside quoted fields are handled correctly. The first row is treated as the header and supplies the JSON keys. Each subsequent row becomes an object whose keys are the headers and whose values come from the cells.

When type inference is enabled, each cell is checked against strict rules: a value matching a JSON number pattern becomes a number, true and false become booleans, and null becomes JSON null. Leading-zero strings like 007 and grouped numbers like 1,000 deliberately stay strings so IDs and codes are not mangled. The output is then joined with \n so every object sits on its own line.

Example and notes

Given this CSV:

id,name,active
1,Ada Lovelace,true
2,"Hopper, Grace",false

the converter produces:

{"id":1,"name":"Ada Lovelace","active":true}
{"id":2,"name":"Hopper, Grace","active":false}

Notice the quoted comma inside "Hopper, Grace" is preserved as part of one field. For BigQuery loads, set the source format to NEWLINE_DELIMITED_JSON; for Elasticsearch, remember the bulk API needs an action line between documents, which this tool does not add — it emits the raw document stream.