JSONL Validator & Formatter
Validate and format JSON Lines — one JSON object per line.
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Paste JSONL to validate each line.
Overview
JSONL validator and formatter
Validate JSON Lines (JSONL / NDJSON) where each line is a separate JSON object — common for logs, ML datasets, and streaming APIs. See per-line errors, then format valid files to compact one-object-per-line output.
What is JSONL?
JSONL is newline-delimited JSON: one complete JSON value per line, with no wrapping array and no commas between records. Data platforms like BigQuery, Snowflake, Elasticsearch bulk APIs, and ML training pipelines consume JSONL efficiently because they can stream it line-by-line instead of loading a whole array into memory.
How validation works
Paste or upload a .jsonl file and JsonDrift parses each line independently. Every line that fails to parse is reported with its line number and the specific error, so you can jump straight to the problem instead of scanning the whole file. Formatting then compacts each valid line to minimal one-object-per-line JSON.
Common JSONL errors
- A trailing comma at the end of a line (JSONL lines are standalone)
- Wrapping the records in a [ ... ] array (that's plain JSON, not JSONL)
- A record split across multiple lines instead of one line each
- Unescaped newlines inside string values
- A stray blank line in the middle of the file
Where JSONL is used
JSONL is the default interchange format for logs and large record sets. If you have a normal JSON array and need JSONL, use the JSON to JSONL converter; to go the other way, use JSONL to JSON. Once each line validates, the format is ready for bulk indexing, warehouse loads, and fine-tuning datasets.
FAQ
Frequently asked questions
How do I validate a JSONL file?
Paste or upload the file and JsonDrift checks every line, reporting the line number and error for any record that isn't valid JSON.
Why is my JSONL invalid?
The most common causes are wrapping records in an array, trailing commas, or a single record spanning multiple lines. Each line must be one complete, standalone JSON value.
Is JSONL the same as NDJSON?
Yes. NDJSON (newline-delimited JSON) is the same format.
Can blank lines be included?
Blank lines are skipped during validation, so trailing newlines won't cause an error.
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