Inspect fields in a JSON or JSONL file

Choose a supported format

JSON must contain an object or an array of objects. JSONL or NDJSON contains one object per non-empty line. Choose the matching format before analysis.

Only top-level fields are described. Nested objects and arrays stay grouped: the explorer does not flatten their properties into columns.

Example: missing, empty and null

[{"name":"A","note":null},{"name":"B","note":""},{"name":"C"}]

note: one null, one empty string, one missing value
These situations are counted separately

Explore and export

1. Import the file and analyse with the correct format.
2. Inspect structure or preview, search for a field name and check its observed types.
3. Export structure as JSON or CSV. This describes fields and counts; it does not convert all records into a table.

Precision and limits

Within one object, repeated keys keep their last value. Numbers use JavaScript precision: very large integers may be rounded. Keep identifiers as strings when every digit matters.

10 MB, 50,000 records, 500 fields, one million cells; preview of 100 rows and 20 fields, analysis limited to 30 seconds. Counts describe the file read, not a guaranteed schema for future files.

CSV and JSON explorers keep separate sessions in this tab. Processing is local; download results before closing or changing language.