You can use any of these. They are FREE....
For Windows
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DJ Mix Lite : http://www.djmixpro.com/djmixlite/djmixlite.html
DJ Mix Lite is designed to play continuous music with cross fading, beat matching mixes between songs.DJ Mix Lite has built in Beatlock Technology, that makes it beat-aware. This technology does not alter your sound files, it just analyses them to find the beats. Knowing the beats, it is able to perform fully automatic quality DJ mixes. This is the ultimate mixing player. It is also a good tool to make mixed cassettes or CDs.
HammerHead Rhythm Station : http://www.threechords.com/hammerhead/download.shtml
HammerHead is a simple TR-909-like drum computer program aiming at the dance-scene. You can use it to create perfect Techno loops, Jungle patterns or House beats, but it's also suitable for Hip Hop, Triphop, Rap, Industrial and almost any other music you can think of.HammerHead features six separate channels, 29 built-in drum sounds, six complete breakbeats and the possibility to import six samples of your own. You can save your patterns to completely noise-free CD-quality wave files to use them with your sampler, tracker or sequencer program.
Tunchy : http://mrd.ath.cx/tunchy/index.html
Tunchy is a FREE Full Featured Real Time MP3 Mixer for DJs
Manual or Auto Crossfading, Fully configurable Fade In & Out, 4 Independent Decks, 4 Tempo/Pitch Levels, WAV, MP3 and M3U support, Full Keyboard Control, Wheel Mice support , Very intuitive, easy to use interface.
For MAC
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Audiophile : http://mac.softpedia.com/get/Audio/Audiophile.shtml
Audiophile is an easy to use DJ software application. Live updating crossfader, · Balance Control · 2 Band Equalizer with display,· Auto-fading, · Infinitely expandable via the wonders of OpenSource!
Mix : http://www.macshareware.com/review/mix
Unique audio loop mixer. Mix is an experimental graphical real time audio loop mixing app inspired by AudioPad. Just drag in loop files and arrange to mix in real time. This is an early prototype and I'd appreciate any feedback on how to improve it.Unique audio loop mixer. Mix is an experimental graphical real time audio loop mixing app inspired by AudioPad. Just drag in loop files and arrange to mix in real time.
DeKstasy :
http://www.macupdate.com/info.php/id/11504/dekstasy OR http://sourceforge.net/projects/dekstasy/files/
DeKstasy is a DJ application for Mac OS X. It provides automatic beat-finding and seamless beat-locked playback of up to four tracks simultaneously, contains a built-in mixer, and is so rock-solid you won't believe it's free software.