Newline Delimited JSON

Introduction

Two types of equivalent formats of line-delimited JSON are:

• Newline Delimited Javascript Object Notation (NDJSON) — The old name was Line Delimited JSON (LDJSON), but was renamed to avoid confusion with JSON-LD[#]
• Javascript Object Notation Lines (JSON Lines, JSONL)[#]

NDJSON makes use of the fact that the JSON format does not allow return and newline characters within primitive values (in strings those must be escaped as “\r” and “\n”, respectively) and that most JSON formatters default to not including any whitespace, including returns and newlines. These features allow the newline character or return and newline character sequence to be used as a delimiter.

In the past the NDJ specification (“newline-delimited JSON”) allowed comments to be embedded if the first two characters of a given line were “//”. This could not be used with standard JSON parsers if comments were included. The current version of the specification (“NDJSON - Newline delimited JSON”) no longer includes comments.

References and Further Reading

• Contributors of Wikipedia: JSON streaming: Newline-Delimited JSON. Wikimedia Foundation, Inc.
• Thorsten Hoeger, Chris Dew, Finn Pauls, Jim Wilson: NDJSON - Newline delimited JSON. NDJSON.org.
  A standard for delimiting JSON in stream protocols.
• ndjson - Newline Delimited JSON. NDJSON.org.
  Official website of the NDJSON format. Has links to libraries in various programming and scripting languages to decode and encode it.
• JSON Lines. JSONLines.Org.
  Official website and specification of the JSON Lines format.