Kiteworks, formerly known as Accellion, Inc., is an American technology company that secures sensitive content communications over channels such as email, file share, file transfer, managed file transfer, web forms, and application programming interfaces. It was founded in 1999 in Singapore and is now based in San Mateo, California.

The Kiteworks Private Data Network consolidates file and email data communications onto a single platform, enabling organizations to reduce data privacy exposure risk and demonstrate conformance with a variety of data privacy regulations.

In 2022, Kiteworks stated that its products were used by over 3,800 organizations worldwide.

The company was founded as Accellion in Singapore in 1999 and was originally focused on distributed file storage. The company moved to Palo Alto, California and shifted its focus on secure file transmission. Accellion reached a total funding of about $35 million in 2011, and it was valued at $500 million in 2014. The company's chief executive officer, Yorgen Edholm, credited aversion to "National Security Agency—style snooping" as a factor in their success.

In January 2012, Accellion raised $12.2 million in funding from Riverwood Capital to continue their expansion.

In 2016, Accellion started to focus on security and compliance and released features that included data security, governance, and compliance. They also began integrations with major cybersecurity independent software vendors (ISVs).

In April 2020, the company received $120 million investment from Bregal Sagemount.

In late 2020, a zero-day exploit in Accellion’s legacy File Transfer Appliance (FTA) product led to data breaches of dozens of government and private organizations. The vulnerabilities were confirmed only in the FTA and not in the Kiteworks platform, which has a separate codebase. Accellion later announced it would stop supporting its legacy FTA product starting April 30, 2021.