Tops Online Judge

Welcome to TopsOJ - a robust, lightweight, and powerful online math solving platform with thousands of problems for anyone who is interested. Track your progress and rise the ranks!

TopsOJ is a


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The Modern Way to Practice Math.

Problem Collection

Explore our extensive collection of over 8000 problems, featuring contests such as AMC and AIME, and our own unique challenges.

High-Quality Contests

Participate in our high-quality contests authored by our expert problem committee.


An engaging math game testing your intuition for triangle centers.

Supportive Community

We have a thriving and large community focused on math and TopsOJ.

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"Instead of boringly grinding problems away on your own, TopsOJ lets you rise the ranks and track your progress — so that you never lose motivation! Also, games like Triangulate will ensure that your freehand geometry diagrams are near-perfect. Take that, IMO 2023 P2!"

— Ming Yang / IMO Silver Medalist

"In addition to TopsOJ's innovative way of practicing multiple choice and numerical answer math problems, they also provide daily challenges and seasonal contests/events to help students stay competitive throughout the year."

— Eddy Liu / Coached 2/6 members of the 2024 Canada IMO team and 4/4 members of the 2024 Canada EGMO Team

"In my opinion, TopsOJ is one of those few ways to practice math that deliver both enjoyment AND results. Whether you're preparing for AMC, AIME, or even MOs, TopsOJ has got something for you! As a staff member at TopsOJ, it's also safe to say that our original contests are unique and high quality, so sign-up for the next one!"

— Joshua Liu / 280 USAJMO index and perfect scorer on the AMC 10, USAJMO HM

Latest Contests

Join our exciting global contests! Tackle unique, high-quality problems and win amazing prizes.

Prize Contest
TxO Math Bowl

A huge team contest open to all middle school, high school, and university students! Created in collaboration with OCMC (

Prize Contest
March Break Contest

A slightly harder than AIME-level March Break contest with gift card prizes! This contest had 15 problems, with the hardest ones reaching MO level.

Prize Contest
Canada Math Contest #2

A contest created by the Canada Math organization, hosted on TopsOJ! This contest had 15 problems, and was an excellent AIME mock for those preparing for AIME 2024.