How to make a reaction video on iPhone
The reaction format — original clip plus your face responding to it — isn't locked to TikTok's duet button. With a video collage app you can react to any video from your library and post the result anywhere: Reels, Shorts, TikTok or a group chat.
Step by step
Record your reaction
Play the original video on another screen (or from memory) and film yourself with the front camera. Get the whole reaction in one take — you'll trim it later.
Open a collage app and import both clips
In Video Grid Collage (free on the App Store), add the original video and your reaction clip.
Choose the layout
Side-by-side puts you and the original at equal size; a stacked top/bottom split mimics the classic duet look; mixed layouts can make the original larger and your reaction smaller in a corner-style frame.
Sync the reaction on the timeline
This step sells the video: trim your reaction so your response lands exactly on the moment it reacts to. Each clip has independent in/out points.
Set the ratio and style
9:16 for short-form platforms. Add a text layer for context ("reacting to my first video ever") and tune spacing and corners.
Export and post
Render in high quality and upload wherever your audience is.
What makes reaction videos work
- Light your face at least as well as the original clip — viewers watch the reaction, not the source.
- Sync is everything: a reaction that lags half a second behind the moment feels fake. Nudge the in-point until it lands.
- Keep the original recognizable — if it's a vertical clip, side-by-side; if horizontal, stack it above your reaction.
- A short text hook ("wait for it…") in the first seconds lifts watch time.
Try it yourself — free
Video Grid Collage · 4.8 on the App Store · combine up to 9 videos in one frame