TikTok's thumbnail is the first thing viewers see before the video autoplays. In search results and profile pages, it's the ONLY thing they see. A single-frame thumbnail captures at most one moment. A grid thumbnail captures 3–4 key moments (the hook, the middle reveal, the satisfying ending) telling the full story before anyone presses play.\n\nEffective TikTok grid strategies: (1) the transformation sequence: before/during/after in a vertical stack of three (perfect for skincare, cleaning, renovation), (2) the reaction sandwich: setup → reaction → result in a vertical stack of three, (3) the product showcase: 2×2 grid showing four angles or color variants, (4) the tutorial preview: Strip of 3 showing step 1 → step 2 → step 3.\n\nExport at 1080×1920px (format Stories 9:16, nécessite rotation manuelle) (9:16 portrait): TikTok's native format. Use 2–4px white spacing between cells. For text overlays, add your hook phrase ('You won't believe #3') on the grid before exporting. MergeFrame processes everything locally: your unreleased content stays private.