David Callicott needs to be online to run his small company, GoodLight Natural Candles in San Francisco.

Dozens of orders from wholesale customers like Whole Foods and Bed Bath & Beyond are relayed online each day to fulfillment warehouses, which send out Mr. Callicott’s paraffin-free candles. The GoodLight website accounts for 15 percent of its sales, which could reach $1.5 million this year; the e-commerce behemoth Amazon makes up another 10 percent. And many of the company’s business documents are stored in cloud-based data centers.

But the costs of doing business on the internet may be about to rise.

A proposal on Tuesday by the Federal Communications Commission would undo so-called net neutrality rules that barred high-speed internet service providers from adjusting website delivery speeds and charging customers extra for access.

Without those regulations, GoodLight and other smaller businesses fear they may not have a level digital playing field to compete against deep-pocketed industry giants that could pay to get an edge online.