Here are a few marketing ideas to make use of the blank back side of a business card:

Add a testimonial: Print a glowing customer review or testimonial on the back of your card to add social proof and encourage potential customers to try your products or services.

Promote a special offer: Use the back of your card to showcase a special discount or promotion that potential customers can use when they visit your store or website.

Include a call to action: Encourage people to visit your website, follow you on social media, or sign up for your newsletter by including a clear call to action on the back of your card.

Feature a product or service: Use the space to showcase one of your best-selling products or services with an eye-catching image and a brief description.

Share your brand story: Use the back of your card to share your brand story or mission statement to help customers understand what makes your business unique and why they should choose you.

Add a QR code: Include a QR code that directs people to your website, a special offer, or a promotional video for your business.

Show off your credentials: If you have won awards or certifications in your industry, include them on the back of your card to help establish credibility and trust with potential customers.