Caption Forge
Add text, boxes, circles, triangles, and arrows to a video. Each one on its own timeline. Render MP4 or WebM in the browser.
Drop in any video, then layer text captions and simple shapes — boxes, circles, triangles, and arrows — on top. Each element gets its own start/end on the timeline, so a caption can appear at 0:03 and disappear at 0:07 while a red box highlights the same spot. Drag elements on the video to position and resize. Drag them on the timeline to set when they show up. Export the whole thing as MP4 or WebM. No upload, no signup, no watermark.
Adding a quick caption or a red box-and-arrow to a screen recording usually means opening a video editor, importing the clip, fiddling with effects panels, and exporting twenty minutes later. Caption Forge does the 90% case in the browser: open the page, drop the clip, drag a text block on, render. Tutorial highlights, store-page bullets, social posts — fast.
- 01Drop a video file (MP4, WebM, MOV, M4V, MKV). Plays right in the page.
- 02Scrub to where you want an overlay to start, then click + Text, + Box, + Circle, + Triangle, or + Arrow.
- 03Drag the overlay on the video to move it. Pull a corner handle to resize.
- 04Tweak color, fill, stroke, font, size, alignment in the properties panel on the right.
- 05Drag the colored bar on the timeline to set when the overlay shows up. Pull either end to lengthen or shorten its run.
- 06Hit play to preview at any time. Add as many overlays as you want.
- 07Pick MP4 or WebM, set Quality, leave Keep audio on, click Render. Download the result.
- Render speed runs at real time — a 30 second clip takes about 30 seconds because the canvas captures the live playback.
- MP4 export works in Chrome and Edge. Firefox and Safari should fall back to WebM.
- Nothing leaves your machine. The video stays in your browser the whole time.
- Very long clips (over a few minutes) plus many overlays may slow the live preview — the export still runs frame-accurate.
Is Caption Forge free, and does it watermark my video?
Yes, completely free. No account, no upload, no watermark on the export.
How do I add text or captions to a video in the browser?
Drop your video into Caption Forge, scrub to the frame where the caption should start, click + Text, and type. Drag the text on the video to position it. Drag the colored bar on the timeline to set when it appears and disappears. Hit Render to encode an MP4 or WebM you can download.
Can I add arrows or circles to highlight something on screen?
Yes — + Arrow draws an arrow at the playhead, + Circle drops an ellipse, + Box drops a rectangle, + Triangle drops a triangle. Each has its own fill, stroke, and color controls. Drag to position and resize. Each shape has its own time window on the timeline, so a highlight can appear and disappear with the action.
Does the audio survive?
Yes. Keep audio is on by default — the original track is captured directly from the video element and muxed into the output. Toggle it off if you want a silent export.
What output formats are supported?
MP4 (H.264 + AAC) where the browser supports it — Chrome, Edge, recent Safari — and WebM (VP9 / VP8 + Opus) everywhere. WebM is the safe default if MP4 is greyed out.
Can I export captions as a .srt subtitle file?
Not yet. Caption Forge bakes the overlays into the rendered video. If you need a separate subtitle track, ping the project and we'll look at adding .srt export.
Where does my video go?
Nowhere. The clip plays from a local blob URL, the overlays are drawn on a canvas in your tab, and the export is made by MediaRecorder right in the browser. No upload, no server, no account.
Why is the render slow?
Because the export plays the video at real time through the canvas to capture every frame with overlays composited in. A 60 second clip takes about 60 seconds. It's the trade-off for keeping everything in the browser with no upload.
Your AI forgets. Astryke doesn’t.
These tools stay free. Astryke Hub is the one you pay for: a board your coding agent reads at the start of a session and writes back to at the end, so it never opens cold again.
Start free14 days free, no card. Founding price $12 a month after that.