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OpenSeaMap vs OpenCPN: catalog facts
OpenSeaMap	OpenCPN
Screenshots	Screenshots
Best for: Sailors and paddlers who want free, community-maintained nautical charts	Best for: Sailors who want a full chartplotter on a laptop or onboard computer
Free Free to use and download.	Free Free and open source.
Web	Windows, macOS, Linux, Android
Free charts built on OpenStreetMap Downloads for OpenCPN, Garmin and Lowrance Anyone can add and correct seamarks	Runs on Windows, macOS, Linux, Raspberry Pi and Android Plugin manager with a catalog of community plugins Designed for use at the helm while underway No cost for the software itself
Community data is not an official chart Coverage and depth detail vary by region Some downloadable chart bundles are several years old	Desktop-style interface is less suited to phones than dedicated mobile apps Some chart sets must be obtained separately
Web application	Downloadable app
Not open source	Open source
License not stated	License not stated
No account needed	No account needed
Not stated if it works offline	Offline features available
Official website Full listing and sources Sources for OpenSeaMap openseamap.org Catalog checked September 23, 2026	Official website Full listing and sources Sources for OpenCPN opencpn.org play.google.com/store/apps/details Catalog checked September 23, 2026

“Not stated” means we have not confirmed it. Features can vary by device and plan.

Screenshots