A wiki collecting mathematical and physics problem-solving methods and tricks.
Art of Problem Solving hosts forums, problems, and discussion for high school and undergraduate math and science olympiad competitors.
Forum and archive for sharing and discussing olympiad-level mathematics problems across many competitions.
Academic notes and essays on mathematics, primarily combinatorics and competition topics.
Official IMO 2025 Australia site hosting competition problems and the shortlist.
IMO Math is an archive of International Mathematical Olympiad competition problems and solutions.
A collection of geometry competition problems from Russian mathematical olympiads.
Archive of problems and solutions from Russian mathematics olympiad competitions.
Collection of problems from the Möbius math contest for students.
Archive of geometry olympiad problems for secondary school students.
Online archive of Moscow Mathematics Olympiad past problems.
Archive of Brazilian Mathematical Olympiad competition problems and solutions.