BOULDER - SendGrid Inc., a fast-growing Boulder-based startup, is opening a satellite office in Denver’s LoDo area as it continues its rapid expansion.

SendGrid is developing a cloud-based platform that helps web developers make sure emails reach clients and users, SendGrid chief executive Jim Franklin said. SendGrid has raised $27 million in venture capital since it emerged from TechStars Boulder in 2009, and has about 60,000 companies that are customers.

Among its users are LinkedIn, Foursquare, Tumblr and Pinterest.

The new office, which will be at 1451 Larimer St. in Denver’s trendy Larimer Square, will give SendGrid greater access to developers and employees who live in Denver and even Colorado Springs, Franklin said.

The space, which will be spread over two floors and can accommodate up to 105 employees, fits SendGrid’s need for more room while helping it retain parts of its corporate culture, according to Franklin.

The company considered locations in Broomfield, but decided the company and community were not the best fit.

“Being in downtown Boulder has been a large part of our success, but as we’ve grown, we need more space,” Franklin said. “We found a great space that feels like our Boulder office.”

SendGrid has about 100 employees, 59 of whom are based in Boulder, Franklin said. The company will continue to add employees to its office in Boulder while filling its office in Denver.

SendGrid has another large office in Anaheim, California, and the company has job openings in New York City, Berlin, Boston and London. SendGrid has hired about 50 people this year, and has openings for 42 more.

SendGrid’s success is based on solving a tough problem on which no one wants to spend time. Companies need to send information such as shipping receipts and registration information to clients by email, but the emails often get trapped in spam filters.

Companies and their developers need to figure out how to connect with users, but it is tedious work.

“Developers find it to be a pain, and it’s not sexy or interesting to work on,” Franklin said.

SendGrid’s cloud-based platform allows companies to outsource email deliverability, and a lot of them are taking advantage. According to SendGrid, it sends more than 4 billion emails per month.

SendGrid’s new office is 15,390 square feet, according to Chris Boston of Gibbons-White, who represented the company.

“The space consists of a few private offices and a very open and collaborative environment that is very good for SendGrid,” Boston said.

The property is part of the portfolio owned by Larimer Associates, Boston said. Darrin Revious of NAI Shames Makovsky represented the landlord.