Is there any reliable free tool or software for managing the IP/patent portfolio - mainly for handling the timelimits, costs and for general overview of the patent porfolio (curently about 100 patents)? Currently I use an Excel sheet, but it is not very user friendly.
I'd add this advice: Don't use the same software as your patent lawyers. Once you're going to the trouble of tracking your portfolio, you should also track key dates (i.e. maintenance fee due dates, office action response dates, patent expiration date, etc.). If there is a bug in the software your lawyer uses, you serve as a backup. The lawyer should also use at least two different systems to track dates, but not all lawyers do.
I use Google Sheets. I previously used an Excel spreadsheet, but this way I can allow my patent lawyers read-only access to my own sheet.
Thank you all for your suggestions. Meanwhile I solved the issue by creating Microsoft Access Database. It was my first time using and creating Access DB, I learned it via free youtube tutorials in couple of hours. It took some more time to fill in all the patents/inventions data and optimise it to my needs, but at the end it worked very well, I could easily trace important dates, costs, link one invention with several patents, analyze data, create reports, search for patents by different reference numbers, link them with patent registers etc. Probably OpenOffice Base or similar software could be used for the same purpose. I worked as lawyer (with IP background) in university TTO at that time. Best regards