Best 5 free Chess Software

Arena with houdini. I also have just started using chess position trainer.

It's not free; here's a demo:

http://www.chess.com/download/view/chessanalyse-26

When you analyze a full game in Lucas Chess, it tells you at the end the average difference per move from the computer's top choice for each side.

Also, Arena can tell you how many moves out of the whole game matched the computer's top choice.

Also on this very site, chess.com in the downloads section one can find some very interesting software, books and game collections all free for the downloading. 

My best 5:

1. Scid. Far better than Arena, IMO
2. Stockfish engine.
3. The free high quality databases at PGN mentor
4. The free not so high quality datbase from icofy. Because there are more games by weaker players, there are more traps in there that I can catch out opponents at my own level
5. Problemiste problem software. Comes with a huge collection of mate in x, selfmate, helpmate, reflexmate problems. Can find solutions for problems, and is great for checking your own compositions for errors (duals etc). The free version is limited, but stil very usable.

Lucas is the best for training, also very good for playing - there are about 20 different engines, each has varying strenght verson. External engines could also be installed.

Arena is the best for Analysing games and openings. its even more comfortable to use than Fritz 13 - though the GUI is not the best.

I use scid and arena for various things. I also use stockfish 2.2.2 and Houdini 1.5 that are free. I have a gui that I paid for and load the books from scid into it.

If anyone knows anything that is better than any of these for free, I am all ears...

for Arena i use tomcat opening book >

http://www.chess.com/download/view/tomcat-opening-for-arena-march-2012

i also downloaded some endgame tablebases such as kbnk, krpkr...

http://www.olympuschess.com/egtb/gaviota/

Does anyone know of any free 960 capable engines or GUI's with an engine, that are 960 capable. I keep running into castling issues or simply that the free versions don't offer any analysis...

yes! Arena supports chess960. you can do with free chess engines like Critter & Stockfish. they are not built in with Arena. so you have to download them separately and install them in Arena GUI.

I tried Arena with stockfish and was still getting a castling error...also, Arena didn't seem to offer the type of analysis I was looking for. I am wondering if the full ( paid for ) version offers these features ?

Have you checked the "UCI_Chess960" box in the Stockfish engine configuration? What kind of analysis were you looking for? Both Arena and Stockfish are free; There aren't paid versions.

Yes, I did check the box....

I'd like multi pv analysis

Arena has issues with Chess960, also known as FRC, since it does not use so-called "Shredder Notation", which most engines do now: see the link below. Arena uses other notation, which fewer new engines support (as I understand it).  

Arena is a good GUI, but not for Chess960.  If the engine uses Shredder Notation, and most do, Arena will say "illegal move" after castling.  This is no way around this except possibly using something like polyglot, but I have never bothered.

By Vasik Rajlich   Date 2010-06-30 06:53

http://rybkaforum.net/cgi-bin/rybkaforum/topic_show.pl?tid=17942

More info:

It is also possible that PolyGlot is useful in combination with
Arena(!): Arena Chess960 works correctly in xboard mode but it seems
not compatible with the official UCI standard.  With PolyGlot it is
possible to include Chess960 UCI engines by using the xboard protocol
instead.

https://sites.google.com/site/chess2u/Polyglot

Yep, it appears that KilgoreBass is right. I confirmed that Arena chokes with an illegal move comment in the debug window when it hits the first castling move. Umm, maybe try Winboard?

I assume it is possible to use PolyGlot to convert UCI to Winboard, then run an engine in Arena as Winboard.  But as I said, I never bothered with this work-around.  

Maybe the next version of Arena, if it ever comes out, will give the option to chose the type of Chess960 notation, like ChessGui does. 

hmm... there is castling problem. i dont know well, but think its setting co-ordination problem?

i faced the same problem in chess.com's turn-based chess960, i was not being allowed to castle, while i fulfilled all criteria! and had to move a inferior move.

i heard Houdini 3.0 supports chess960. but how does it work?

in chess.com nine sixty, i have had to move a piece that wasnt technically in the way, in order for it allow it. it is probably a glitch. ex...bishop on e one had to be moved, even though the king on f one and the rook on h one had a clear path, after the knight @ g one was moved....

sorry i cant use anything that requires the alt key on chess.com right now on my android, some glitch or something...