JSONL ↔ Excel (XLSX) Converter
100% client-side. No upload — even the .xlsx file is built in your browser.
Convert
JSONL ↔ Excel (XLSX) Converter
Build a real .xlsx workbook from a JSONL file, or read an Excel sheet back into JSONL — entirely in your browser. The output is a standard OpenXML workbook that Excel, Google Sheets, Numbers, and LibreOffice all open cleanly. Nested keys are flattened with dot notation (user.email, tags.0) so every leaf gets a column. 100% in-browser.
How it works
JSONL → XLSX flattens each record, collects every observed key as a column, and builds the .xlsx in-memory using a tiny ZIP writer and the OpenXML SpreadsheetML schema. The file is delivered as a download — nothing is uploaded.
XLSX → JSONL reads the workbook's first sheet (or the named sheet),
uses the first row as keys, and emits one JSON record per data row. Empty cells map to
missing keys, not null, so the JSONL stays clean.
Tips & common pitfalls
- Column count limit. Excel allows up to 16,384 columns. JSONL with hundreds of unique flattened keys is no problem, but a deeply-nested file with thousands of variant keys can exceed the limit — flatten more aggressively or use the CSV converter instead.
- Types are detected. Numeric-looking values become numbers;
"007"stays a string. Dates need an ISO format (2026-05-11) to be detected as such. - One sheet per workbook. If you need multiple sheets, split first with the JSONL Splitter and convert each chunk.
Example
Input:
{"id":1,"user":{"name":"alice","email":"[email protected]"}}
{"id":2,"user":{"name":"bob","email":"[email protected]"}}Output workbook:
id | user.name | user.email
1 | alice | [email protected]
2 | bob | [email protected]