Cat post neuter surgery

I just was wondering if this looks normal for a male cat 4 days after surgery. He is acting normal and eating well!

I don't think that amount of swelling is normal. He may need an antibiotic. I would definitely show this to your vet asap.

I second the suggestion to show this to your vet ASAP.  I am not a vet but to me that does not look normal and does look infected.  The swelling and redness remind me of the infection one of my female cats got in her spay incision.  I took her to the vet immediately and they actually had to drain the infected area and put her on antibiotics. It was not terribly expensive for the treatment.  After the incision was drained and she was put on antibiotics the infection went away quickly.  My cat was also eating and acting completely normal at the time too.  My vet was surprised she was not showing any signs of being in pain.  

Yikes Definitely NOT normal at all. Please take your cat back to the vet to address the swelling and redness. The surgical site may have become infected (was your cat licking it post sugery?) and antibiotics may be needed. You can probably also email the picture to the vet and the vet may be able to prescribe something for you to pick up. Might save you from paying for a full exam.