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OpenSeaMap nautical chart of the Baltic coast with navigation controls and a coordinate grid

Compare OpenSeaMap with alternatives

OpenSeaMap vs OpenCPNOpenCPN is a free open-source chartplotter for Windows, macOS, Linux and Android that uses chart sets you obtain, including OpenSeaMap downloads, rather than a web chart.
OpenSeaMap vs iNavXiNavX includes free NOAA US charts and supports over 25 chart providers on phones and tablets, with AIS and GRIB weather, but commercial charts are bought separately.
OpenSeaMap vs Aqua MapAqua Map shows official NOAA, USACE and CMOR charts offline on Android and iOS, but it is freemium, closed source and focused on US waters and the Bahamas.
OpenSeaMap vs ArgoArgo includes nautical charts in its free plan on web and mobile, with offline charts and crowdsourced reports, but it is a proprietary service rather than community-editable chart data.