Managify - Create & organize all your documents in a single platform.

Mendeley - Easily organize your papers, read & annotate your PDFs, collaborate in private or open groups, and securely access your research from everywhere.

Files Board - Organize & manage your documents, photos and videos

Zotero - Zotero is a free, easy-to-use tool to help you collect, organize, cite, and share research.

Sismics Docs - Lightweight full-featured document management system 📁

Qiqqa - Qiqqa is a free research and reference management software. It can be used in many organizational projects from the academic to the personal to the business endeavor. Read more about Qiqqa.