I can't think of many situations where you may want to look up IP address information when you are offline. Two possible options include analyzing a log file, for instance that of a computer's firewall or that of a website while offline or not connected to the Internet, the other to not leave a trace on the Internet when you look up IP addresses.
A program that is only running locally is only as good as its database as all information need to be available in a local database as the program can't use the Internet to retrieve partial or full information about IP addresses.
Nirsoft's IPInfoOffline is a portable program for the Windows operating system that you can make use of to look up IP address related information. While you should not expect to receive full whois information, it provides you with a set of information that you may find useful after all.
The program displays an empty text field to you which you can add a set of IP addresses to. You can either type in the addresses manually, or paste them into the form from another document. The look up itself is fast thanks to the local nature of the program. Here you find all Internet Protocol addresses listed in individual rows in a table like format. For each IP, you get the IP range, the organization, the assigned date, the country and country code, and the index.
The usual Nirsoft features have been added to the program. You can create a HTML report, or save the set of data as txt, XML or csv files for further investigation or safe keeping, or safe the selected information to the Windows Clipboard for further processing. If you have an IP address database of your own, you can use it instead of the program's internal database.
As I said earlier, you should not expect a complete whois look up, but if you need less information, then this program may be what you are looking for. If you prefer complete information, check out an online service such as Whois.net.
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