Step 1 / source
Choose the source
Drop one file here
Choose the flat ndjson object records you want to turn into styled xlsx worksheet.
Checking publication status...LOCAL TABLE CONVERTER / NDJSON TO EXCEL
NDJSON to Excel
Convert flat newline-delimited JSON records into a genuine styled and filterable XLSX worksheet while preserving JSON scalar cell types.
Processed in this browserOne UTF-8 .ndjson or .jsonl file up to 5 MB, 50,000 flat object records, 200 union columns, 1,000,000 cells, and 20 MB workbook output.
NDJSON - 50,000 flat records
No file upload
This operation runs with browser APIs. Nirmion receives catalogue requests, not the selected source bytes.
Original stays unchanged
The converter creates a separately named output. It never writes back into the source file.
Bounded work
One UTF-8 .ndjson or .jsonl file up to 5 MB, 50,000 flat object records, 200 union columns, 1,000,000 cells, and 20 MB workbook output.
Plain-language method
How NDJSON to Excel works
Nirmion parses every non-blank line independently, requires one flat scalar object per line, builds union columns in first-seen order, writes strings, finite numbers, booleans, and nulls as workbook values, freezes and styles the header, sizes columns, and adds a filter row.
- 01Choose a valid source
Use one complete JSON object per physical line. Nested objects, nested arrays, malformed lines, and files with no records are rejected.
- 02Review the conversion choices
Skip ignores empty physical lines; Reject treats them as a format error. The worksheet name is cleaned to Excel limits.
- 03Inspect the separate result
The result ends in _nirmion_tools.xlsx. It is a real workbook generated from the reviewed records, not a renamed text file.
Useful when
Practical jobs this tool handles
- Review service logs that emit flat NDJSON.
- Filter approved event records in Excel.
- Hand a bounded line-oriented export to analysts.
Before converting
Check the source and destination rules
- Validate each line independently.
- Confirm union-column order and null cells.
- Review leading formula-like strings after export.
Know the boundary
Know what the destination format cannot keep
Excel cannot preserve the distinction between a missing property and JSON null when both become blank cells. Nested JSON is rejected rather than flattened ambiguously.
Quick answers
Questions before you convert
The conversion contract is deliberately explicit.
Can one line contain an array?
No. Every line must be a flat object.
Are JSON numbers written as numbers?
Finite JSON numbers and booleans are written as typed workbook values.
Are formulas executed?
No. Source strings are written as values, and the converter never evaluates formula text.