Add Simple and Calculated Columns to JSON Lines Data

Add simple and calculated columns to your JSON Lines / NDJSON data quickly

Drop your JSON_LINES (.jsonl) file here (or click to browse).
(100 MB or less file)
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Add Columns Tools JSON Lines Tools
Convert JSON Lines using an API
Add Columns

This tool makes it simple to add new columns to your JSON Lines / NDJSON file. You can create fields with fixed values, empty placeholders, or even dynamic content using formulas and other data in your file. It’s useful for when you need to enrich your data, add missing fields before importing into another system, or prepare your file for further processing. Whether you're working with customer lists, inventory spreadsheets, or survey results, this tool gives you full control over how and where to insert new columns.

JSON Lines / NDJSON

JSON Lines (also known as NDJSON β€” Newline Delimited JSON) is a text format where each line is a self-contained, valid JSON value, typically a JSON object. It is widely used for streaming data, log files, and large data exports because files can be read and written one record at a time without loading the entire document into memory. Common file extensions are .jsonl and .ndjson.