Clink is another investment app that lets you invest in the stock market with as little as $1 per day.

Choose to invest larger amounts on a daily, weekly, bi-weekly or monthly basis. Clink charges $1/month.

Susan Shain says her money used to sit in a bank savings account, barely collecting interest and costing her a monthly fee.

She found Clink and was happy with how easy the app was to use. "It didn't require me to get my master's in finance to understand the terms, or give up my firstborn to pay the fees."