These pages describe Calamo Pro 0.1 for Windows, Linux and macOS (beta). Download it and try it free for 14 days.
Formats
- Text: CSV, TSV and .txt with a comma, semicolon or tab. The delimiter and the encoding are detected: UTF-8 (with or without BOM), UTF-16, and the Windows code pages Excel uses in Central and Western Europe (1250 and 1252). If the letters still look wrong, choose the encoding next to the file name: ISO 8859, the other Windows code pages, KOI8, Shift_JIS, EUC-JP, GBK, GB18030, Big5 or EUC-KR. A CSV saved from such a file is written in the same encoding.
- Workbooks: .xlsx, .xlsm, .xlsb, .xls and .ods, one sheet at a time.
- Parquet: .parquet files are read with every value as text, the way DuckDB prints it (1.5, 2026-11-04, true); a missing value is empty. Browsing one file can also save the rows shown as Parquet, every column as text.
- JSON and XML: a JSON array of objects, JSON Lines (one object per line) or an object holding such an array; nested objects become columns like
address.city, and numbers stay as written (1.50 stays 1.50). In XML, every element under the root is a row, and its attributes and child elements are the columns. These files are read into memory whole, so they suit files up to a few hundred MB. Browsing one file can also save the rows shown as JSON or XML. - A title above the header (a report name and a date in the first rows) is skipped and the label says which row the header is in.
- Repeated or empty column names get a number, so every column is kept.
Measured speed
Measured on one desktop (AMD Ryzen 9 9900X, 59 GB RAM), version 0.1, November 2026. Your computer will be faster or slower; with less memory, Calamo works on disk and takes longer.
| File | Task | Time |
|---|---|---|
| 77 MB, 1.2 million rows | open to browse | 0.3 s |
| 4.3 GB, 64.5 million rows | open to browse | 9.0 s |
| 733 MB, 450,000 rows × 1,000 columns | open to browse | 10.4 s |
| 4.2 GB and 4.3 GB, 64 million rows each | compare by key | 53 s |
Privacy
Calamo reads the files from your disk. Workbooks, Parquet files and files that are not UTF-8 are converted to a private temporary copy, removed when you close the app. Nothing is uploaded; the app does not send file names, column names or values anywhere.