NDJSON to JSON - Convert Line-Delimited JSON

Convert NDJSON to JSON array in your browser. Perfect for streaming data, log files, BigQuery exports. Fast, private, local processing.

NDJSON Input

Paste your NDJSON data (one JSON object per line)

Error Handling

Skip invalid lines (continue on errors)

Fail on first error

Output Format

Pretty-printed (indented)

Minified (compact)

JSON Output

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Frequently Asked Questions

NDJSON (Newline Delimited JSON) is a format where each line is a valid, self-contained JSON object separated by newline characters. Unlike standard JSON arrays, NDJSON doesn't require opening and closing brackets, making it ideal for streaming data. Each line can be parsed independently, which is perfect for processing large datasets that don't fit in memory or for appending new data without modifying existing content.

NDJSON, JSON Lines, and JSONL are essentially the same format with different names. They all refer to newline-delimited JSON where each line contains a complete JSON object. The format is standardized and uses the .ndjson, .jsonl, or .jsonlines file extensions interchangeably. The key rule is one JSON value per line, typically objects, though arrays and primitives are also valid.

NDJSON offers several advantages: 1) Streamable - you can process data line-by-line without loading the entire file into memory, 2) Appendable - new records can be added to the end without parsing the entire file, 3) Fault-tolerant - corruption in one line doesn't affect others, 4) Parallelizable - different lines can be processed simultaneously, and 5) Efficient for logs - each log entry is independent and timestamped. These benefits make NDJSON ideal for big data, logging systems, and real-time analytics.

Use NDJSON when working with: streaming data pipelines, application logs, database exports (especially from BigQuery, MongoDB, Elasticsearch), analytics data that's written incrementally, systems that need to process data line-by-line, ETL processes where data is transformed record-by-record, or any scenario where you're dealing with large datasets that might not fit in memory. It's the preferred format for data scientists working with big data tools and for microservices that exchange event streams.

The converter reads your NDJSON input line-by-line, parses each line as an independent JSON object using JSON.parse(), and collects valid objects into an array. Empty lines are automatically skipped. The resulting array is then serialized back to JSON format, either pretty-printed with indentation for readability or minified for smaller file size. The entire process happens in your browser using JavaScript, with no server uploads required.

Yes, but with browser memory limitations in mind. Since the conversion happens entirely in your browser, the maximum file size depends on your available RAM. For most browsers, files up to 100-200MB can be processed comfortably. For extremely large files (gigabytes), consider using command-line tools or splitting the file into smaller chunks. The tool will display the number of lines processed and any errors encountered, helping you monitor the conversion progress.

The tool offers two error handling modes: 'Skip invalid lines' continues processing even when it encounters malformed JSON, collecting all valid objects and reporting errors at the end. This is useful for partially corrupted data. 'Fail on first error' stops immediately when invalid JSON is detected, showing you exactly which line caused the problem. Both modes display line numbers and error messages to help you identify and fix issues in your source data.

Yes, but this specific tool converts NDJSON to JSON. For the reverse conversion (JSON array to NDJSON), you would use a JSON to NDJSON converter. The reverse process takes a JSON array and writes each element as a separate line. Both conversions are lossless as long as your data consists of objects or values that maintain their structure when serialized.

BigQuery and Elasticsearch use NDJSON for bulk imports because it's highly efficient for large-scale data operations. NDJSON allows these systems to: stream data without loading everything into memory first, process records in parallel across multiple nodes, recover from partial failures (one bad record doesn't corrupt the entire import), and append new data without rewriting existing files. BigQuery exports to NDJSON by default, and Elasticsearch's bulk API accepts NDJSON for indexing operations.

Absolutely. All conversion happens entirely in your browser using client-side JavaScript. Your NDJSON data never leaves your computer or gets uploaded to any server. This makes it safe for converting sensitive data like application logs, user analytics, or database exports. The tool works completely offline once the page is loaded, ensuring your data remains private and secure.

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