Is our salvation based on works ?

Paul doesn’t say. “work for your salvation.” 

Philemon 2:12

Therefore, my beloved, as you have always obeyed, not as in my presence only, but now much more in my absence, work out your own salvation with fear and trembling;

Romans 3:28

Therefore we conclude that a man is justified by faith apart from the deeds of the law.

James 2:24

You see then that a man is justified by works, and not by faith only.

James wouldn't contradict himself. In the previous verse (James 2:23)  he is making a reference to Genesis 15:6 which states Abraham was declared righteous for believing. This was before Abraham did any work. Works were the result of genuine faith. 

James 2:23 

and the Scripture was fulfilled which says, “And Abraham believed God, and it was reckoned to him as righteousness,” and he was called the friend of God.

Genesis 15:6

Then he believed in the Lord; and He reckoned it to him as righteousness.

This is harmony with Paul's teaching of good works that follow faith. 

Ephesians 2:8-9

For by grace you have been saved through faith; and that not of yourselves, it is the gift of God; not as a result of works, so that no one may boast.  For we are His workmanship, created in Christ Jesus for good works, which God prepared beforehand so that we would walk in them.

James was addressing the "said faith" mentality that people had. A "said faith" is not a real faith. James says the demons believe. Faith of Christians is a deep trust in the finished work of Christ. 

James 2:14

What does it profit, my brethren, if someone says he has faith but does not have works? Can faith save him?

James 2:19

You believe that there is one God. You do well. Even the demons believe and tremble!

John 19:30

Therefore when Jesus had received the sour wine, He said, “It is finished!” And He bowed His head and gave up His spirit.

2 Timothy 1:9

who has saved us and called us with a holy calling, not according to our works, but according to His own purpose and grace which was granted us in Christ Jesus from all eternity,