- AJATT | Table of Contents
- arXiv.org e-Print archive
- EuDML - The European Digital Mathematics Library
- Expository papers by K. Conrad
- Grothendieck Circle
- History of Philosophy without any gaps
- Inference: International Review of Science
- Library Genesis
- LMFDB - The L-functions and Modular Forms Database
- MathOverflow & Math.StackExchange
- nLab (The n-Category Lab)
- Number Theory in Montreal
- Number Theory Web
- Numdam, the French digital mathematics library
- Polymath1Wiki
- ProofWiki
- Quanta Magazine
- /sci/ guide for self-learning & timewasting
- Sci-Hub: removing barriers in the way of science
- Unpublished stuff by Kevin Buzzard
- Wikipedia (especially good for gathering bibliography)
- Zentralblatt MATH

- Shtetl-Optimized, by Scott Aaronson
- Xena Project, by Kevin Buzzard
- Gower's Weblog, by Timothy Gowers
- Stop Timothy Gowers! !!!, by Nikolai Ivanov
- Combinatorics and more, by Gil Kalai
- What's new, by Terrence Tao
- Annoying Precision, by Qiaochu Yuan
- The n-Category Café, by many people

- chessbrah, hosted by GM Eric Hansen
- ChessNetwork, by NM Jerry
- Chess Club and Scholastic Center of Atlanta, hosted by GM Ben Finegold
- Saint Louis Chess Club's channel

- Fermilab
- Frederic Schuller's YouTube channel
- Graduate Mathematics, by some kind anonymous
- ICTP Mathematics (Abdus Salam International Centre for Theoretical Physics)
- Insights into Mathematics, by N. J. Wildberger
- Institut des Hautes Études Scientifiques (IHÉS)
- Institute for Advanced Study (IAS - Princeton) (see also: videos)
- Instituto de Matemática Pura e Aplicada (IMPA)
- Kyoto-U OpenCourseWare
- Mathematics at HSE (Higher School of Economics)
- MathDoctorBob, by Robert Donley
- NASA Goddard Space Flight Center
- princentonmathematics' channel
- Taylor Dupuy's Math Vlog
- UConn Mathematics (University of Connecticut)

- 3Blue1Brown, by Grant Sanderson
- ElectroBOOM, by Mehdi Sadaghdar
- Kurzgesagt - In a Nutshell, founded by Philipp Dettmer
- NileRed, by Nigel Braun
- Numberphile, Sixty Symbols & Periodic Videos, by Brady Haran
- PBS Space Time, hosted by Matthew O'Dowd
- Physics Videos by Eugene Khutoryansky
- Real Engineering, by Brian McManus
- Smarter Every Day, by Destin Sandlin
- standupmaths, by Matt Parker
- Technology Connections, by Alec Watson
- Veritasium, by Derek Muller
- Vsauce & D!NG, by Michael Stevens
- What I've Learned, by Joseph Everett

- Academy of Ideas, by two brothers from Canada
- Jordan B. Peterson's YouTube channel
- Langfocus, by Paul Jorgensen
- Matt vs. Japan, by Matt

- A single paper everyone should read?
- Awfully sophisticated proofs for simple facts
- Best online mathematics videos?
- Blackbox Theorems
- Consequences of the Riemann hypothesis
- Examples of common false beliefs in mathematics
- Examples of major theorems with very hard proofs that have not dramatically improved over time
- Examples of unexpected mathematical images
- Famous mathematical quotes
- Important formulas in combinatorics
- Jokes in the sense of Littlewood: examples?
- Magic trick based on deep mathematics
- Math puzzles for dinner
- Mathematical podcasts/audio
- Mathematical "urban legends"
- New grand projects in contemporary math
- Not especially famous, long-open problems which anyone can understand
- Proofs without words
- Suggestions for good notation
- The most outrageous conjectures in mathematics
- Video lectures of mathematics courses available online for free

- Do you read the masters?
- Downsides of using the arXiv?
- Has philosophy ever clarified mathematics?
- Is rigour just a ritual that most mathematicians wish to get rid of if they could?
- Should I not cite an arxiv.org paper which otherwise seems to be unpublished?
- The half-life of a theorem, or Arnold's principle at work
- What's a mathematician to do?

- A road to Inter-Universal Teichmuller Theory
- Barrelled, bornological, ultrabornological, semi-reflexive, ... how are these used?
- Center-commutator duality (m.se)
- Convergence of \(\sum (n^3\sin^2(n))^{-1}\)
- How many orders of infinity are there?
- How to memorise (understand) Nakayama's lemma and its corollaries?
- Is there a high-concept explanation for why characteristic 2 is special?
- Is there an introduction to probability theory from a structuralist/categorical perspective?
- Knuth's intuition that Goldbach might be unprovable
- Philosophy behind Mochizuki's work on the ABC conjecture
- The origin of sets?
- What are "perfectoid spaces"?
- What is a Frobenioid?
- What were the main ideas and gaps in Yoichi Miyaoka's attempted proof (1988) of Fermat's Last Theorem?
- Why are there so many smooth functions?
- Why do roots of polynomials tend to have absolute value close to 1?