Useful apps for GNU/Linux systems
KeePass is a free open source password manager, which helps you to manage your passwords in a secure way. You can put all your passwords in one database, which is locked with one master key or a key file. So you only have to remember one single master password or select the key file to unlock the whole database. The databases are encrypted using the best and most secure encryption algorithms currently known (AES and Twofish).
Also portable app: http://portableapps.com/apps/utilities/keepass_portable .
Pwgen is a small, GPL'ed password generator which creates passwords which can be easily memorized by a human.
For Windows a GUI version of PWGen is available on http://pwgen-win.sourceforge.net/
It can create large amounts of cryptographically-secure passwords or passphrases (from word lists). It uses a random pool to gather entropy from user inputs and system parameters. Offers text encryption and random data file creation, too.
Thunderbird is a free, open source, cross-platform e-mail, news and instant messaging client. The project strategy is modeled after Mozilla Firefox.
It supports POP (storing mail locally on your hard drive so that it can be accessed without an internet connection), and IMAP. It features excellent mail filter capabilities and management.
Thunderbird has strong support for using multiple accounts and identities, including automated signature features.
Chat functionality is built in, so you can enjoy real-time conversation with your contacts, right from your favorite messaging application, with multiple supported networks. Thunderbird makes it easy to search through both past conversations and received emails.
Thunderbird can also function as an RSS/Atom feed reader, and has a large selection of add-ons that extend it with calendar support, PGP support, integration with online services and much more.
Available also as portable app: http://portableapps.com/apps/internet/thunderbird_portable
The Tor software protects you by bouncing your communications around a distributed network of relays run by volunteers all around the world: it prevents somebody watching your Internet connection from learning what sites you visit, it prevents the sites you visit from learning your physical location, and it lets you access sites which are blocked.
The Tor Browser lets you use Tor on Windows, Mac OS X, or Linux without needing to install any software. It can run off a USB flash drive, comes with a pre-configured web browser to protect your anonymity, and is self-contained.
Wire is a secure and private messenger for phones, tablets and desktop. Crystal clear voice and video calls, private group chats, file sharing, audio and video messages - everything is end-to-end encrypted. Wire works on Android, iOS, Windows, MacOS, Linux and any modern web browser.
Sublime Text is a sophisticated text editor for code, html and prose - any kind of text file. You'll love the slick user interface and extraordinary features.
Sublime Text may be downloaded and evaluated for free without an expiration time limit, however a license must be purchased for continued use.
Evince is a document viewer for multiple document formats. It currently supports pdf, postscript, djvu, tiff, dvi, cbr, cbz, etc.
The goal of Evince is to replace the multiple document viewers that exist on the GNOME Desktop with a single simple application. Evince is also capable of displaying, adding and editing PDF annotations (comments).
LibreOffice is a free and open-source office suite that is compatible with other major office suites, and is available on all operating systems. It is an independently-developed version of the OpenOffice.org suite.
The office suite includes:
LibreOffice - Writer, a word processor with similar functionality and file support to Microsoft Office Word . It has extensive WYSIWYG word processing capabilities, but can also be used as a basic text editor.
LibreOffice - Calc , a spreadsheet program, similar to Microsoft Office Excel . It has a number of unique features, including a system which automatically defines series of graphs, based on information available to the user.
LibreOffice - Impress , a presentation program resembling Microsoft Office Powerpoint . Presentations can be exported as SWF files, allowing them to be viewed on any computer with Adobe Flash installed.
LibreOffice - Draw , a vector graphics editor and diagramming tool similar to Microsoft Office Visio . It provides connectors between shapes, which are available in a range of line styles and facilitate building drawings such as flowcharts. It also includes features similar to desktop publishing software such as Scribus and Microsoft Office Publisher .
GoldenDict is an open-source dictionary program for PC computers that gives translations of words and phrases for different languages. It allows use of several popular dictionary file formats simultaneously.
A free, ad-sponsored, mobile version is available for Android devices. It fully supports Lingvo, Babylon, StarDict, Lingoes and Dictd dictionary files.
Eye of GNOME is the official image viewer for the GNOME Desktop environment. With it, you can view single image files, as well as large image collections. The Eye of GNOME supports a variety of image file formats. The GdkPixbuf library determines which file formats Eye of GNOME can load and save. If the appropriate plugins are installed on your system, Image Viewer will be able to open more image formats than those listed below.
XnConvert is an easy image converter for graphic files, photos and images available on Windows, MacOSX and Linux.
It supports more than 400 file formats (jpeg, tiff, png, gif, camera raw, jpeg2000, WebP, OpenEXR, ...).
You can resize, add a watermark, change contrast, brightness or gamma, apply filters and many other things.