BRL-CAD is a powerful cross-platform Open Source combinatorial Constructive Solid Geometry (CSG) solid modeling system that includes interactive 3D solid geometry editing, high-performance ray-tracing support for rendering and geometric analysis, network-distributed framebuffer support, image and signal-processing tools, path-tracing and photon mapping support for realistic image synthesis, a system performance analysis benchmark suite, an embedded scripting interface, and libraries for robust high-performance geometric representation and analysis.

Scribus is an application for professional visual layout of printed documents (newspapers, magazines, brochures, literature, etc.) capable of creating high-quality pages for any purpose - be it replication for printing or electronic distribution.
Scribus supports all the features of professional publishing systems, such as extensive capabilities for layout and pre-press preparation of text, the CMYK color model, Spot Colors, the ICC color output management system, and the creation of PDF files.
This is similar to AdobeInDesign or QuarkXPress.

qCAD is a professional CAD system, similar to AutoCAD, designed for creating mechanical engineering drawings and architectural plans. You can create technical drawings such as building plans, interior plans, mechanical plans, or schematics.
You can also easily create and edit drawings with ISO templates and save files in DXF format. The DXF format is used by many CAD systems.

FreeCAD is an extensible CAD/CAM system that includes some key concepts such as macro recording, workspaces, the ability to run as a server, and dynamically loaded application extensions.

FreeCAD can import and display CAD models in IGES, STEP and BRep formats, as well as meshes in STL, BMS, AST and Wavefront OBJ formats.

Alchemy is a drawing project aimed at exploring how we can draw, draw and create in new ways on computers.
Alchemy is not software for creating a finished piece of art, but a sketching environment that focuses on the absolute beginning stage of the creation process. Alchemy allows you to experiment and visually explore a wider range of ideas and possibilities.

Graphical interface (Qt) for creating, editing, and rendering flam3 IFS fractal flame images, which can be saved as png files.

Hugin is a convenient application that allows the user not only to automate the process of stitching photos, but also allows you to manually, flexibly set parameters.
✔mosaic assembly mode, which allows you to assemble panoramas from pictures taken from different angles;
✔creation of polygonal masks, with which you can exclude unnecessary objects from the final panorama;
✔visualization of the entire project in the hardware-accelerated preview dialog, with which you can quickly assess the quality of alignment of overlapping images relative to each other;
✔grouping pictures taken with exposure bracketing - previously, time was wasted on aligning them relative to each other, even when it came to pictures of static objects taken from a tripod

Inkscape (an alternative to Corel Draw) is a vector graphics editor, convenient for creating both artistic and technical illustrations (including use as a general-purpose CAD program, which is also facilitated by the ease of sharing drawings). It is widely used to create illustrations, icons, logos, diagrams, maps, as well as web graphics.

It contains advanced tools for work, comparable to the capabilities of Adobe Illustrator, CorelDRAW and Xara Xtreme. You can read save images in many formats including SVG, AI, EPS, PDF, PS and PNG. Inkscape has a comprehensive set of tools, a simple interface, support for many languages, and is extensible with custom add-ons.

Designed for creating full-fledged animated films. Allows you to avoid creating intermediate frames, eliminating the need to manually draw each frame.

Pinta is an easy-to-use graphics editor. Its goal is to provide a simple and convenient experience for ordinary users.

Some of the supported features:
- image adjustment (automatic level correction, black and white image, sepia, ...)
- effects (motion blur, glow, warp, ...)
- working with layers
- unlimited depth of undo/redo actions
- drawing tools (brush, pencil, shapes, ...)