Online Tools for Mathematicians

• OASIS - Operator Algebras Searchable Information Site
• Mathoverflow.net
• arXiv
• arxivist - your personal guide to the arxiv
• scimeter
• ​Google Scholar
• Mathscinet (requires University account)
• Zentralblatt Math
• GDZ (Göttingen Digitisation Centre)
• The Manifold Atlas
• Detexify (draw a symbol and get the $\LaTeX$ code for it)
• Mathpix (convert screenshots to $\LaTeX$ code)
• Online Videos of the MSRI
• Seminars archive of the Isaac Newton Institute 

Blogs

• Secret Blogging Seminar
• Noncommutative Geometry

Mathematics Departments

• Cardiff Mathematics - People and Events
• Cardiff University
• Westfälische Wilhelms Universität Münster
• Georg-August-Universität Göttingen