https://techcrunch.com/2021/10/01/pspdfkit-raises-116m-its-first-outside-money-now-nearly-1b-people-use-apps-powered-by-its-collaboration-signing-and-markup-tools/

An under-the-radar, bootstrapped startup from Vienna, Austria — a hit with developers for technology that underpins user experience for some of the world’s most popular apps — is doubling down on momentum and announcing its first outside investment, in the form of a large growth round of funding.

PSPDFkit — which provides APIs and an SDK that developers use to power document processing features like e-signing, document viewing and editing, collaboration and much more — has raised €100 million ($116 million). The funding is coming from a single investor, Insight Partners.