Due to increasing digitization, e.g. of medical records or land certificates, digital archives are needed which securely preserve data in the long term. There are several solutions described in literature that allow digital archives to provide guarantee of integrity and of authenticity as well as proof of existence indefinitely. In this talk, we first compare these solutions regarding their performance. Then, we extract reusable components and explain how they can be combined in a modular fashion. This allows archivists to create custom solutions that fulfill their requirements in the best possible way. We also present a prototype implementation of such a modular long-term archiving system. It includes a web application which guides non-expert users through the processes of creating and maintaining digital archives. Furthermore, the system allows transferring documents from one archive to another without losing their protection, independent of the archive configurations involved.