If you've ever tried to knock out a quick Instagram Reel or TikTok slide post, you know the drill: download an app, make an account, hit the export button, and — surprise — there's a watermark in the corner unless you subscribe.
[ReelStudio] skips all of that. It's a free tool that runs in your browser, turns images into captioned slides or adds text overlays to video, and exports without a watermark or a sign-up.
Two modes: Slides and Video
The tool splits into two workflows depending on what you're making.
Slides
You upload one or more images and write your text lines. The mapping is neat: one line = one slide. Drop in a single image and every caption lands on that same background; drop in multiple and each line moves to the next image. It's basically a carousel/slideshow generator driven by a plain list of text.
Video
Upload a video, write your text lines, and each new line appears on the next segment of the clip. So instead of scrubbing a timeline and keyframing captions, you just type the lines in order and they get distributed across the video.
Formatting that matches the platforms
You're not left guessing about dimensions. ReelStudio gives you the three aspect ratios that actually matter:
9:16 — Reels / TikTok
1:1 — square post
16:9 — YouTube
On top of that you get control over text position (top / center / bottom), text size, text color, and a background style for the caption — a solid band, a shadow, or none. There's also a "seconds per line" setting, with 0 meaning auto-timing.
The export detail worth knowing
Video exports in WebM. Instagram, TikTok, and YouTube all accept WebM through their in-browser upload flows, so for most people that's a non-issue. If you specifically need MP4 (say, for an app that's picky about it), any free converter handles it. Worth flagging up front so nobody's caught off guard.
Why this is a nice piece of engineering
What I like here — same as a lot of good "small tools" — is how much it does without a backend. Rendering captioned slides and overlaying text on video are both things the browser can handle natively these days (canvas, the MediaRecorder/WebM export path, etc.). No upload to a server, no processing queue, no account to tie it to. You bring the media, the browser does the work, you download the result.
For developers that's a fun reminder of how capable the client is now. For everyone else, it just means fewer steps and nothing leaving your machine.
Good for...
Spinning up a quick carousel or slide post from a list of captions.
Adding sequential text overlays to a short video without opening a full editor.
Making content in the right aspect ratio the first time, watermark-free.
Try it here: linksforeveryone.com/reelstudio
Have you built canvas- or MediaRecorder-based tools like this? I'm curious how others are handling in-browser video export — share your approach in the comments.
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