The new manuscript portal for Germany - Handschriftenportal - will become the central information platform for medieval and early modern manuscripts in German collections, providing descriptive information on manuscripts as well as digital facsimiles. In a decentralized approach, digital images from various institutions will be integrated leveraging the International Image Interoperability Framework (IIIF). Both images and texts will later be the target of user generated annotations. This does and will provide various challenges for the Handschriftenportal, such as: publishing reliable URIs for digitized manuscripts with truly persistent content in the institutions’ backends; linking portal data with external authority data; linking annotations with author information; handling born-digital texts in the context of the IIIF image viewer Mirador; enhancing annotations to citable and persistent micro-publications. Also, there should be ways to feed information on user-generated content back to the institutions holding the original manuscripts. The talk will report on the project's current implementations and future plans, while - at the time SWIB 2021 will take place - the Handschriftenportal will just recently have gone live. The Handschriftenportal is a DFG-funded joint project of the State Libraries in Berlin and Munich, the Herzog August Library Wolfenbüttel and Leipzig University Library.