Anonymity
Pidgin is a free and open source Instant Messaging (IM) client that lets you organize and manage your different (IM) accounts through a single interface. The Off-the-Record (OTR) plug-in designed for use with Pidgin ensures authenticated and secure communications between Pidgin users. Before you can start using Pidgin you must have an existing IM account, after which you will register that account to Pidgin. For instance, if you have an email account with Gmail, you can use their IM service GoogleTalk with Pidgin. The log-in details of your existing IM account are used to register and access your account through Pidgin.
Both Pidgin and OTR are available for Microsoft Windows and for GNU/Linux. Another multi-protocol IM program for Microsoft Windows that supports OTR is Miranda IM. For the Mac OS we recommend using Adium, a multi-protocol IM program that supports the OTR plugin.
Pidgin is strongly recommended for IM sessions, as it offers a greater degree of security than alternative messaging clients, and does not come bundled with unnecessary adware or spyware which may compromise your privacy and security.
Off-the-Record (OTR) messaging is a plugin developed specifically for Pidgin. It offers the following privacy and security features:
Authentication: You are assured the correspondent is who you think it is.
Deniability: After the chat session is finished, messages cannot be identified as originating from either your correspondent or you.
Encryption: No one else can access and read your instant messages.
Perfect Forward Security: If third party obtains your private keys, no previous conversations are compromised.
Pidgin: http://www.pidgin.im/