Used informally among friends or in casual conversations, not in formal settings. I'm not surprised Jack fixed your phone; he's quite the techie.
Pro Tip 2/3
Positive Connotation
Implies admiration for someone's tech skills, without the negative implications 'geek' might have. Our team won because we had a techie handling all the technical challenges.
Pro Tip 3/3
Not Profession Specific
Doesn't necessarily mean a professional; could be a hobbyist with a keen interest in technology. Even though she's a doctor, she's the techie of the family.