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Thanks for this great framework and I would like to know can I download all librairies (charts,etc) and work with them except if I will sell my application I have to bye the license ?
if for example I visit this page https://vaadin.com/spreadsheet there is a pricing panel on the left so it does it means what ?
Some add-ons, such as Charts and Spreadsheet, require a commercial license. The license is required for doing development work with the libraries. Whether you sell the application or not doesn't matter, you need to buy the license in all cases. The licenses are not for applications, but for the developer (you) who uses the libraries during development. You can use a license to develop as many applications as you want. The licenses are personal (although transferable), so each developer need to have his or her own license.
That said, you can obtain free trial licenses with 30-day expiration to evaluate if the add-ons work for you.
Thank you for your response and could you please tell me about the green button to download the Beta Version ?