What JSONL Viewer does
JSONL and NDJSON store one JSON value on each line. This viewer keeps original line numbers, reports invalid rows, filters by literal text or an exact field path, and exports filtered data as JSONL or a JSON array. Processing happens in a local Worker so the page stays responsive.
Common uses
- Inspect structured logs without uploading them
- Find errors by message or a specific JSON field
- Turn filtered NDJSON records into a JSON array
Privacy and limitations
File content is processed in this browser tab only and is not automatically saved. No account or server upload is required.
Validate important output in the actual language, database, or target platform.
Frequently asked questions
How large can a file be?
Up to 20 MiB, 100,000 non-empty records and 500,000 total JSON nodes. The page displays 100 records at a time; limits are checked before accepting the document.
What happens to malformed lines?
Every invalid line is counted and the first 100 error details are shown. Exports are blocked until you explicitly allow exporting only valid records; malformed lines are never silently removed.
Are large numbers preserved?
Yes. Integer and decimal tokens remain unchanged in exported JSON. Long on-screen previews are clearly labelled and never used as full exports.
How do field filters work?
Use a path such as $.message, $.user.id or $[0] to limit a case-insensitive text search. Paths do not execute code.