XLS to JSON for migrating old Excel data into apps

Data migrations often begin with a folder of XLS files from a system that no longer exists: customer lists, inventory, old price tables. Getting that into a new application means turning it into JSON, and the binary XLS format makes most quick scripts fail.

XlsConverter reads XLS directly and writes clean JSON with types per column. If your files are already in the modern format, XLSX to JSON is the matching page, and Excel to JSON explains nested keys and shapes in detail.

How to convert XLS to JSON in three steps

1. 1Upload one XLS file or a batch of them.
2. 2Select sheets, header row and JSON shape.
3. 3Convert and download one JSON per workbook or a combined file.

Messy headers and continuation sheets in old XLS exports

Old XLS exports were made for people, not programs. Headers span two rows, contain line breaks, or repeat the same label like Amount twice. JSON keys must be unique and predictable, so we flatten two row headers, remove line breaks and number duplicates (amount, amount_2). You see the final keys in the preview before converting.

Because XLS stops at 65,536 rows, larger datasets were split across Sheet1, Sheet2 and Sheet3 with the same columns. With the merge option, sheets that share a header become one JSON array, which is what a migration script expects. Sheets with different structures stay separate under their own names.

Text in XLS uses the code page of the machine that saved it, and numbers formatted as text are common in old files. We decode the code page and apply the same per column type inference as for modern files, so prices become numbers and codes stay strings. If the destination is a database rather than an app, XLS to SQL writes the insert statements directly, and XLS to CSV covers simple bulk loaders.