fSpy is a free and open-source application for quick and easy still image camera matching on Windows, Mac and Linux platforms, developed by Stuffmatic (Per Gantelius) from Sweden. It can calculate the properties (field of view, focal length, position and orientation) of the real camera from a photo, and transfer this data to the virtual camera of 3D software for use.

Software developers are likely to use databases in the course of their projects. Different databases generally require different database connection tools, such as Navicat for MySQL, PL/SQL for Oracle, SQL Server Management Studio for Microsoft SQL Server. Of course, we can also choose to use universal tools that support almost all databases at the same time, such as DbVisualizer.

There are two classic books in the Domain-Driven Design (DDD) field, they are Eric Evans's Domain-Driven Design and Jimmy Nilsson's Applying Domain-Driven Design and Patterns. The latter is also regarded as a practical exercise for the essence of Domain-Driven Design and Martin Fowler's Patterns of Enterprise Application Architecture. In short, it is a must-read book for .NET developers that takes readers on a practical, erudite journey into the world of domain-driven design.

Krita (formerly called KImageShop, Krayon) is a free, open-source and cross-platform digital painting software developed by Krita Foundation (part of the KDE Community) from Sweden. It is fully functional, capable of the entire painting process from drafting, lining, coloring to post-adjustment; can draw concept sketch, illustration, cartoon, animation, scene and 3D mapping; supports digital board, pressure sensing, anti-shake, layers, filters, color management, and other functions.

National flag/logo icons can be occasionally used in some design works, such as the region selection on a multilingual website or software installation. But just very few designers are willing to design these icons from scratch. Instead, most of us choose to direct find the ready-made materials for use.