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qtVlm vs PredictWind: catalog facts
qtVlm	PredictWind
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Best for: Cruising and racing sailors who plan routes around weather	Best for: Sailors planning passages around wind and weather
Free + paid options The GRIB viewer is free; mobile and tablet apps, chart packs and the GRIB service are paid.	Free + paid options Some forecasts are free; routing and advanced features need a paid plan.
Windows, Android, iOS	Web
Weather routing with departure-time comparison Reads S57, S63, raster and MBTiles charts AIS and NMEA instrument support Iridium GO certified	High-resolution wind forecasts Weather routing and departure planning together Aimed specifically at sailing and ocean racing
Mobile versions and chart packs are paid Wide feature set takes time to learn	Advanced features are paid Proprietary hosted service
Downloadable app	Web application, Hosted service
Not open source	Not open source
License not stated	License not stated
Not stated if an account is needed	Not stated if an account is needed
Not stated if it works offline	Not stated if it works offline
Official website Full listing and sources Sources for qtVlm meltemus.com apps.apple.com/us/app/qtvlm/id999110023 Catalog checked September 24, 2026	Official website Full listing and sources Sources for PredictWind predictwind.com Catalog checked September 24, 2026

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

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