Gcal is a program to calculate and print calendars on the command-line. Calendars can be printed in 1-month, 3-month or whole-year views. In addition, eternal holiday lists can be generated for many countries, which can be complemented by user-made lists of fixed dates to make an agenda. Gcal can also calculate astronomical data, such as the phases of the moon, and supports alternative calendar formats: Julian, Gregorian, Islamic, Chinese and more.

ConfClerk is an application written in Qt, which makes conference schedules available offline. It displays the conference schedule from various views, support searches on various items (speaker, speech topic, location, etc.) and enables you to select favorite events and create your own schedule.

At the moment ConfClerk is able to import schedules in XML format created by the PentaBarf conference management system (or frab) used by e.g. FOSDEM, DebConf, FrOSCon, Grazer LinuxTage, and the CCC congresses.

ConfClerk is targeted at mobile devices but works on any system running Qt.

By default, date2name gets the modification time of matching files and directories and adds a datestamp in standard ISO 8601+ format YYYY-MM-DD at the beginning of the file or directory name.

ddate displays the Discordian date and holidays of a given date. The Discordian calendar was made popular by the "Illuminatus!" trilogy by Robert Shea and Robert Anton Wilson.

gsimplecal is a lightweight calendar application written in C++ using GTK. Launched once, it pops up a small calendar applet, launched again it closes the running instance. It can additionally be configured to show the current time in different timezones.

Date is a header only C++ library that extends the chrono date algorithms library for calendar dates and durations. It also provides the <tz.h> library for handling time zones and leap seconds.

Hebcal is a program for converting between Hebrew and Gregorian dates, and generating lists of Jewish holidays for a given year. Shabbat, holiday candle lighting, and havdalah times are approximated using your location.

It can also show daily prayer times, the weekly Torah reading, and the daily leaf of Talmud. The program can help with counting of the Omer or with calculation of Hebrew yahrzeits, birthdays, or anniversaries.

Libical is an implementation of the iCalendar protocols and protocol data units.

LibHdate is a small library for the Hebrew calendar and times of day, written in C, and including bindings for C++, pascal, perl, php, python, and ruby. It includes two illustrative command-line programs, hcal and hdate, and some snippets and scripts written in the binding languages.

Khal is a standards based console calendar program, able to synchronize with CalDAV servers through vdirsyncer. It includes both a CLI and a TUI named ikhal.

Ccache is a compiler cache. It speeds up recompilation by caching previous compilations and detecting when the same compilation is being done again. Supported languages are C, C++, Objective-C and Objective-C++.

The GNU Compact Disc Input and Control Library (libcdio) is a library for CD-ROM and CD image file access. It allows the developer to add CD access to an application without having to worry about the OS- and device-dependent properties of CD-ROM or the specific details of CD image formats. It includes pycdio, a Python interface to libcdio, and libcdio-paranoia, a library providing jitter-free and error-free audio extraction from CDs.

CDemu is a software suite designed to emulate an optical drive and disc (including CD-ROMs and DVD-ROMs).

libcdio-paranoia is an implementation of CD paranoia libraries based on libcdio.

libMirage is a CD-ROM image access library. It supports the following formats: B6T, C2D, CCD, CDI, CIF, CUE, ISO, MDS, MDX, NRG, TOC. It is written in C and based on GLib. Its aim is to provide uniform access to the data stored in various image formats.

GNU Xorriso is a tool for copying files to and from ISO 9660 Rock Ridge, a.k.a. Compact Disc File System, file systems and it allows session-wise manipulation of them. It features a formatter and burner for CD, DVD and BD. It can operate on existing ISO images or it can create new ones. xorriso can then be used to copy files directly into or out of ISO files.

Libcue is a C library to parse so-called cue sheets which contain meta-data for CD/DVD tracks. It provides an API to manipulate the data.

Cdrkit is a suite of programs for recording CDs and DVDs, blanking CD-RW media, creating ISO-9660 file system images, extracting audio CD data, and more. It's mostly compatible with cdrtools.

cdrdao records audio or data CDs in disk-at-once (DAO) mode, based on a textual description of the contents. This mode writes the complete disc – lead-in, one or more tracks, and lead-out – in a single step and is commonly used with audio CDs. cdrdao can also handle the bin/cue format, commonly used for VCDs or disks with subchannel data.

DVDStyler is a DVD authoring application which allows users to burn video files in many formats to DVD discs, complete with individually designed menus. It can be used to create professional-looking DVD's with custom buttons, backgrounds and animations, from within a user-friendly graphical interface.

Asunder is a graphical audio CD ripper and encoder. It can save audio tracks as WAV, MP3, Ogg Vorbis, FLAC, Opus, Wavpack, and Musepack. It can use CDDB to name and tag each track automatically, and it allows for each track to be by a different artist. Asunder can encode to multiple formats in one session, and it can create M3U playlists.

libudfread is a C library for reading UDF file systems. UDF is a file system mostly used for DVDs and other optical media. It supports read-only media (DVD/CD-R) and rewritable media that wears out (DVD/CD-RW).

Libisofs creates ISO 9660 (also known as ECMA-119) file system images which can either be written to POSIX file objects or handed over to libburn for being written directly to optical media. It can read metadata of ISO 9660 filesystems, manipulate them, and use them to produce new complete file system images or add-on images to be appended to the read file system image. Supported extensions to ISO 9660 are Rock Ridge, Joliet, AAIP, zisofs.

RipIT is used to extract audio from CDs.