Free AI data tool · Formats
JSONL validator
Quick answer
Paste or upload a JSON Lines file. Each non-empty line is parsed as JSON, and every failure is reported with its line number.
Limit: 10 MiB or 25,000 records
Your sample is processed in this browser. File contents are not uploaded.
Supported input
.jsonl / .ndjson text, up to 10 MiB or 25,000 records.
How it works
The file is split on LF or CRLF. A UTF-8 byte-order mark is removed. Each line is passed to the browser's JSON parser. Empty lines are skipped or reported as errors, depending on your choice. A trailing newline at the end of the file is not counted as a line.
Limitations
- Checks JSON syntax only, not field structure — use the schema or chat validators for that.
- The valid-record export excludes every rejected line.
Questions
- How do I validate a JSONL file?
- Paste or upload it and press Validate. Each line is parsed on its own, and every broken line is listed with its line number. You can then download only the valid records.
- What makes a JSONL line invalid?
- Usually a missing quote or brace, single quotes instead of double quotes, a trailing comma, or a record split across two lines. Each line must be one complete JSON value.
- Is my file uploaded?
- No. The file is read and processed in this browser tab, and its contents are not sent to SourceX or anyone else. Closing the tab or pressing Reset clears it.
Learn the format
Related tools
Chat dataset validatorCheck a messages[] chat dataset for structure, roles, empty content and assistant turns.Dataset quality checkerMeasure completeness, exact duplicates and text length in a CSV, JSON or JSONL sample.JSON to JSONL converterTurn a JSON array — or an array you pick inside an object — into JSON Lines.
Request data in this format
Need licensed business data delivered in this format? Describe it and we'll scope it.
Request data in this format