What is the best DJ software for starters?
There are a few excellent DJ software that are easily accessible by beginner and professionals alike. 

Serato DJ is a legendary DJ software used by turntablists and scratch DJs all over the world thanks to its stable and easy to use interface. It is known for its tight, accurate control or the ability to mix tracks fairly easily. Serato DJ is also certified and integrated on some hardware from brands like Denon, Roland and Numark.

Rekordbox DJ by Pioneer DJ is a professional DJ software and platform that integrates everything from cloud music management to creative performance capabilities. It enables a seamless DJ experience via multiple cloud-connected devices, anywhere in the world. It is also seamlessly integrated to Pioneer DJ hardware like CDJs or XDJs.

Is all DJ software paid?
Although paid software generally offers more features, there are some free to use DJ software available for beginners like Virtual DJ, Cross DJ Free and DJ ProDecks. However, there are also free/trial to use versions of Serato DJ and rekordbox DJ with fewer features than their paid versions.

Do I need specific controllers and gear to make full use of the software?
In the market today, most, if not all DJ equipment manufacturers have partnerships and integrations with different software. For example, all Pioneer DJ hardware functions with rekordbox DJ and typically Denon, Numark or Rane DJ have partnerships with Serato DJ. The software compatibility will be listed on each of the products and can also be found on the product’s website.