TikTok, Instagram Reels, and YouTube Shorts expect 9:16 vertical video. Cropping before upload keeps your subject centered. MBox crop tool includes 9:16, 1:1, and 16:9 presets plus free-form crop with live preview. Export locally when it looks right. Because processing is browser-local, drafts and unreleased campaigns stay off third-party servers — helpful for brands and creators.