xlSlim is available to download and use free of charge. The core functionality of xlSlim will always be free. However premium features require a premium licence. Premium licences can be purchased at

14 day trial licences are created automatically when xlSlim is first run on your PC. Thus you will have the opportunity to evaluate premium features.

This table compares the features available in the free and premium versions:

Feature Comparison
Feature Free Premium
Register Excel functions from Python module functions Y Y
Recognise type hints Y Y
Recognise doc string Y Y
Automatic data type conversions Y Y
Support returning lists from functions Y Y
Access VBA and add-in functions in Python Y Y
Use external Python environments N Y
Support numpy arrays N Y
Support pandas series N Y
Support pandas dataframes N Y
Run Python in a background process N Y

Technical Details

Licensing is provided by licensespring who generously offer free licensing services to startups.

If you are behind a firewall please whitelist on port 443

Offline licence activation is also possible, see Licensing for details.