+1 to the above.  No matter which site you pull from, monitoring your own credit should never harm your credit score.

However, funny story. I used to work for a mortgage collections firm and of course we had the ability to pull credit reports on the borrowers. Well, one of my coworkers decided she would become her own free credit monitoring service and was pulling her own report quite regularly (despite this being an express violation of company policy). She probably viewed it as a nice little perk of working there.

Unfortunately for her, she did not realize she was doing hard pulls every time.  In the end, she not only lost the job but I'd guess a good-sized chunk of her FICO score as well.

That is pretty much the only way you could ever harm your credit score by checking your own report. Whatever .com service you choose to use online, it will always be a soft pull.