Question: I applied for Company A for a job. I applied also for Company B.

Company A has given me an offer. I accepted it, and I canceled all of my other applications, except to Company B. I did it because Company B was a much better job, but I've seen only a small chance for a success.

Company A sent me a contract to sign, and started to organize the starting procedure.

Meanwhile, also Company B has given me an offer. It was a surprise, but I had luck.

Now I need to cancel the procedure for Company A.

Yes, on the paper and on the law is everything okay. I got an offer, I am free to reject it.

But, the sad truth is that I was unthinkably dishonest. They honored me with a job, they trusted me, and I slapped them on the face. That is the truth.

I am ashamed.

What the heck could I do? What?

What should I say to them? I think, I will be forever blacklisted at Company A, and I deserve it, but what should I say them?

Answer: 
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> But, the sad truth is that I was unthinkably dishonest. They honored me with a job, they trusted me, and I slapped them on the face. That is the truth.
> 
> 
> I am ashamed.
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> 
> 

No need to be ashamed, thats just business. You are looking out for your best interest, the company is looking out for theirs..

Since you haven't signed, there's no legal obligation on your side.

> 
> What should I say to them?
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> 
> 

Thank them for their interest in you and their time spent on the application process and tell them you found another job that's more suitable to you.
You could add that they might keep your record for future opportunities.

That's all there is to it - no need to loose sleep or get grey hairs over it, your move is not so uncommon and completely understandable..
People back out of accepting a job offer *all the time*. For a multitude of reasons. A small company with inexperienced staff may be surprised, but for most companies, this is just part of the game. They will just shrug, and move on. For the companies POV, it's better if you abort the process now, then if you would start, and leave during your probation period.

Just send them a letter, addressed to the relevant people, thanking them for their time and trust they put in you, but that you have decided to decline the offer. You don't have tell them any reason.

Will that burn any bridges? Maybe. Some people might remember your name, and decline to talk to you for another opportunity. Some HR agent might put note in your file. (I know recruitment at the company I work for does -- they keep track of every outcome, mostly to track performance as recruitment as a whole; but I also know several people who first declined an offer, and later joined the company; it's not hold against them). Most likely, they won't remember. (Of course, if you work in a field of which there only a few dozens of people working in the whole work, it will be harder to forget a name).

If you find a better position, go for it. You don't have to be loyal to a company you haven't even gotten a first paycheck from.