Is it okay to use a QR code instead of writing social media handles on business cards?

You can, but a QR code should support your handles, not replace them entirely. Some people will happily scan, while others would rather glance at a handle and type it in later. The strongest layout gives them both: a couple of readable handles plus a code for everything else.

• List your top one or two social handles in plain text with small icons on the front or back.
• Add a QR code, ideally on the back, that links to your full online presence.
• Test the code at final print size to be sure it scans reliably from a small card.
• Point the code somewhere useful, like a profile hub, rather than a single fleeting post.