Squarespace, Inc. is an American website building and hosting company based in New York City. It provides software as a service for website building and hosting, and allows users to use pre-built website templates and drag-and-drop elements to create and modify webpages.

In 2003, Anthony Casalena founded Squarespace as a blog hosting service while attending the University of Maryland, College Park. He was its only employee until 2006 when it reached $1 million in revenue. The company grew from 30 employees in 2010 to 550 by 2015. By 2014, it raised a total of $78.5 million in venture capital; added e-commerce tools, domain name services, and analytics; and replaced its coding backend with drag-and-drop features. It began trading on the New York Stock Exchange on May 19, 2021, and was taken private by Permira in October 2024. According to W3Techs, Squarespace is used by 1.9% of the top 10 million websites.

Casalena began developing Squarespace for his personal use while attending the University of Maryland. He started sharing it with friends and family members and participated in a "business incubator" program at the university. In January 2004, he launched Squarespace as do it yourself/drag-and-drop website builder for the public, with a $30,000 seed fund from his father, a small grant from the university, and 300 beta testers who paid a discounted rate. At that time, Casalena was the company's sole developer and employee, and worked out of his dorm room.

By the time Casalena graduated in 2007, Squarespace was making annual revenues of $1 million. He moved to New York City, began hiring, and had 30 employees by 2010. That year, Squarespace received $38.5 million in its first round of venture capital funding led by Index Ventures and Accel Partners, enabling it to hire more staff, continue to develop its software, and double its marketing budget. From 2009 to 2012, it grew an average of 266% in yearly revenue. In April 2014, it received another $40 million in funding. By 2015, it had reached $100 million in revenue and 550 employees.

Squarespace purchased Super Bowl advertising spots in 2014, 2015, 2016, 2017 and 2018. Its 2017 ad won an Emmy Award for Outstanding Commercial. In 2017, it signed a sponsorship deal with the New York Knicks to add the Squarespace logo to their uniforms.

After the Unite the Right rally in 2017, Squarespace received a petition with 58,000 signatures and removed a group of websites for violating its terms of service against "bigotry or hatred" towards demographic groups. In 2017, it raised an additional $200 million in funding, boosting its value to $1.7 billion. This funding was earmarked for reacquiring interests from investors.

In 2018, Squarespace partnered with the Madison Square Garden Company to launch the "Make It Awards", which awarded $30,000 to entrepreneurs (4 winners, totaling $120,000).

Squarespace acquired appointment scheduling company Acuity Scheduling in April 2019. In October 2019, Squarespace acquired Unfold, an app founded by Alfonso Cobo that allows users to editorialize their social media content. In April 2021, the company bought hospitality industry management platform Tock for more than $400 million.