I wanted to know if it's allowed to use custom Google Plus and Twitter social share buttons. I've seen many jQuery plugins using custom designed buttons and I am not sure whether to use them or not.
Is custom google Plus button allowed by Google?
social sharing buttons
There are multiple resources from Google regarding branding guidelines as well as tools for creating buttons. In the buttons policy they state Publishers may not alter or obfuscate a Google+ buttonAndPublisher must use only the official Google-provided icon or a plain text and link combinationThat being said custom buttons are prolific on the web and very hard to police, so you are probably safe to use one, just not  technically compliant to the policy.Google Buttons PolicyGoogle Brand GuidelinesDeveloper custom buttonsTwitter brand guidelinesTwitter assets