How do I add captions to a video?

Upload your video, and the auto caption generator transcribes the speech and adds timed captions automatically. Pick a style, edit any line if needed, then export a captioned MP4 with the captions burned in.

Is this auto caption generator free?

Yes — you can upload, generate captions, edit and preview completely free, without even signing in. Create a free account to export, and every export is free with unlimited videos. Free exports include a small CaptionX watermark; upgrade to Pro to remove it. Your SRT subtitle file is always free with no watermark.

Do I need to install anything?

No. It runs entirely in your browser — no app, plugin or sign-up friction to add captions to a video. (The MP4 export step works best in desktop Chrome or Edge.)

An SRT (SubRip) file is a plain-text subtitle file that lists each caption and its start/end timecodes. Alongside the captioned MP4, you can download an SRT to use in other editors or upload to platforms like YouTube.

How do I add captions on TikTok, Reels or YouTube Shorts?

Generate and style your captions here, export the captioned MP4, then upload that video to TikTok, Instagram Reels or YouTube Shorts. The captions are baked into the video, so they show everywhere.

What languages does it support?

The automatic captions support 50+ languages and the spoken language is detected for you, so you can add captions to videos in most major languages.

Are the captions burned into the video?

Yes — the exported MP4 has the captions hardcoded into the frames, so they always display. If you'd rather have a separate subtitle file, you can also export an SRT.

Is my video uploaded to a server?

No. Your video stays on your device — only the extracted audio is sent to generate the transcript, and the captioned MP4 is rendered locally in your browser.

Auto Caption Generator

Add animated captions to any video — automatically. Upload a clip, auto-generate captions, pick a style, and export a captioned MP4 right in your browser. Got a song instead? Drop an MP3 to turn it into a lyric video. Free to try — no sign-up to generate, and unlimited free exports. No install needed.

Caption Studio

Upload

Add animated captions to your video

Upload a video clip — or drop a song to make a lyric video — auto-generate captions, pick a style, and export an MP4 right in your browser.

Drag & drop your video or song

or click to browse

Video (MP4, MOV, WebM) or audio (MP3, WAV) · up to 10 min · under 2 GB · stays on your device

Upload

Your clip

Edit & style

Review + template

Export

Captioned MP4

Free Online Auto Caption Generator

The fastest way to add captions to a video

Caption X automatically generates captions from your video and burns them in for you — no manual typing, no timeline, no install. It's built for short-form creators who want bold, animated captions that boost watch time on TikTok, Reels and YouTube Shorts.

Automatic captionsAnimated stylesCaptioned MP4 exportSRT exportNo sign-up to try

Why creators use it

Auto captions in seconds — the AI transcribes your speech and times every line.

Animated, scroll-stopping caption styles, not plain subtitles.

Everything runs in your browser, and your video never leaves your device.

How It Works

Add captions to your video in four steps

Step 1

Upload your video

Drop in an MP4 or MOV (up to 10 minutes). Your video stays on your device — only the audio is sent to generate the captions.

Step 2

Auto-generate captions

AI transcribes the speech with word-level timing in 50+ languages, then groups it into clean, readable caption lines automatically.

Step 3

Style your captions

Pick an animated caption template, then fine-tune color, size, position and pop/blur animation. Review and edit any line before exporting.

Step 4

Export a captioned MP4

Captions are burned into your video and downloaded instantly. Free exports carry a small CaptionX watermark (Pro removes it); the SRT subtitle file is always watermark-free.

Best Use Cases

Captions for TikTok, Reels, YouTube Shorts and more

Generate captions once and export a captioned MP4 you can post anywhere. Because the captions are burned in, they display on every platform — no re-uploading subtitle files.

TikTok, Reels & Shorts

Add bold, animated captions that keep viewers watching to the end — the look that performs on short-form video.

Podcasts & interviews

Turn talking-head clips into captioned social posts so people can watch with the sound off.

Accessibility & reach

On-screen captions make your videos watchable in any feed and accessible to more viewers.

Creators & marketers

Get fast, on-brand captions without opening CapCut or Premiere — straight from your browser.

FAQ