open an Excel workbook in the IDE, without Excel

Someone attaches last quarter's numbers to a ticket and it turns up as an .xlsx with more rows than any mail preview will show you. XLSX Lens opens that workbook in an editor tab, streamed, and neither writes to it nor locks it. It runs in IntelliJ IDEA, PyCharm and every other JetBrains IDE on 2024.2 or newer, Android Studio from Ladybug.

installing and opening

Install XLSX Lens from the JetBrains Marketplace, then double-click the workbook in the project tree. One streaming pass spills rows to a scratch index, so the first page renders while a 500,000-row sheet is still loading and memory stays flat. Before a release ships we run it on IntelliJ IDEA Community 2024.2, IntelliJ IDEA Ultimate 2026.2 and Android Studio 2026.1.

XLSX Lens in IntelliJ IDEA: a half-million-row sheet paged 100 rows at a time, the Pro actions in the toolbar — half-million-rows.xlsx: rows 1 to 100 of 499,999 on screen, the sheet list on the left, the Pro actions in the toolbar.

the sheets, the search and one cell at a time

Every sheet is listed with its size in rows and columns once read, hidden ones named as hidden. Merged cells render. A date cell is read by the date system the workbook declares, 1900 or 1904, and the builtin and the common custom number formats are applied, currency and accounting among them. Ctrl+F searches across every row over values, formatted text and formulas, and the cell inspector then shows one cell whole, the value beside the raw stored text, the formula and the format pattern.

Nothing is recalculated, so the cached formula results are what you see rather than fresh ones. A legacy .xls does not open at all, and .csv is never claimed away from the editor that already has it.

free, and what Pro adds

Reading is free. Pro is a subscription with a 30-day trial. It writes a sheet, the search matches or the current filtered view out as CSV, JSONL, Markdown, Parquet or a workbook copy, and it profiles the columns into a report. It also sorts and filters every row rather than the loaded page, and it diffs two workbooks sheet by sheet with the differing cells marked. Formula view and a reload when the file changes on disk are Pro as well. The product page lists both tiers and quotes the price as the store shows it.