MOHS Olympiad Problem Browser

A dependency-free static website for browsing the contest ratings indexed in Evan Chen's Math Olympiad Hardness Scale (MOHS) PDF.

Run locally

You can double-click index.html, or serve the folder with:

python -m http.server 8000

Then open http://localhost:8000.

Features

• Topic filters: Algebra, Combinatorics, Geometry, Number Theory
• Contest filters: IMO, USAMO, USA TSTST, USA TST, USEMO
• Hardness and year ranges
• Search by problem identifier / topic / rating
• Sort by hardness, year, or contest
• Links to AoPS problem pages/searches and PDF archives
• Persistent light/dark mode toggle
• Per-problem progress: Unseen / Attempted / Solved
• Progress filtering and overall completion summary
• Progress is stored locally in the browser; no backend is required

Data & link notes

The ratings and subjects are transcribed from Evan Chen's MOHS index and are subjective.

• IMO PDF links use the official IMO website.
• USAMO PDF links use Evan Chen's public solution notes; his archive explicitly notes these are not MAA's official solution files.
• USA TST/TSTST links use Evan Chen's public problem archive.
• USEMO links use the contest organizer's PDFs.
• AoPS links are direct Wiki links for IMO/USAMO and targeted AoPS searches for contests whose page naming is less stable.

Progress & theme storage

The site uses browser localStorage for two keys:

• mohs-progress-v1 — problem progress states
• mohs-theme — light/dark preference

This keeps GitHub Pages deployment fully static. Progress is device/browser-specific unless you later add an import/export or account-sync feature.