Free Auto Caption Video Generator

Add AI auto captions to your videos free. Whisper AI runs locally in your browser. Choose from 45+ styles, edit text, and export MP4. No watermark, no upload.

Whisper AI
45+ Styles
No Watermark
100% Private

Before you start: the source video is cropped and zoomed to fill the target frame. Drag inside the preview to pan the video. Drag the caption to move it. 45 caption styles with outline, box and glow controls. Original audio is preserved in the export. Nothing is uploaded.

100% secure. Your video never leaves your device.

Everything runs in your browser. No uploads, no sign-up.

Video Trimmer

Cut start and end without quality loss.

Video Compressor

Shrink video for uploads and messages.

Video to GIF

Turn a clip into an animated GIF.

Video to MP3

Extract audio from any video.

Video Upscaler

Enlarge video 2x, 3x, or 4x in your browser.

Audio Recorder

Record and trim audio with a live waveform.

How do I add auto-captions to a video for free?

Upload your video, click "Generate Captions," and let Whisper AI transcribe the audio. Choose a style from 45+ options, fix any typos in the text tab, and hit Render to download your captioned MP4. No watermark, no login.

Price: 100% Free, no credits
Account required: No
Video uploaded: No, runs locally
Watermark: None
AI Model: Whisper Tiny (English)
Caption styles: 45+ pre-designed styles
Output format: MP4 (H.264) + AAC audio
Best for: TikTok, Reels, YouTube Shorts
Max resolution: 1080p Full HD
Works on: Chrome, Edge, Firefox (Desktop)

How to add captions in 3 steps

1
Upload your video
Choose an MP4, WebM, or MOV. The video opens locally in your browser.
2
Generate AI captions
Click "Generate Captions". Whisper AI will listen to the audio and transcribe it in seconds.
3
Style, edit, and export
Choose a style, fix any typos, and click Render to download your captioned MP4.

Free Auto Caption FAQ

Quick answers about accuracy, privacy, and styling.

How do I add auto captions to a video for free?

Upload your video, click "Generate Captions," and let Whisper AI transcribe the audio. Choose a style from 45+ options, fix any typos in the text tab, and hit Render to download your captioned MP4.

Is this auto caption generator really free?

Yes, it is 100% free. There are no watermarks, no hidden fees, and no sign-ups required.

Do I need to upload my video to a server?

No. The entire process (audio extraction, AI transcription, and video rendering) runs locally in your browser using WebCodecs.

Will there be a watermark on my video?

No. Unlike CapCut or other online editors, ToolDeck never adds a watermark to your export.

Are the auto captions accurate?

Whisper is highly accurate for clear English, but background noise or strong accents can cause errors. Use the "Edit text" tab to fix mistakes before rendering.

Can I edit the captions?

Yes. Click the "Edit text" tab in the left sidebar. You can rewrite any line of text. The preview updates instantly.

Can I change the caption style?

Yes. We offer 45+ styles including Neon, Gradient, Vaporwave, Comic, and Classic. You can also change the text color, size, and position.

Does it keep the original audio?

Yes. The original audio is trimmed to match your clip and exported in the final MP4.

What video formats are supported?

MP4, WebM, MOV, and MKV. We recommend MP4 (H.264) for the fastest rendering.

What resolution is the output?

The default output is 1080p (Full HD). We also support 9:16, 1:1, and 4:5 aspect ratios.

Does it work on mobile phones?

It runs in mobile browsers, but desktop is highly recommended. Rendering a video and running the AI model uses a lot of memory.

What is the max file size?

We recommend files under 1GB. Browsers have memory limits, and large files may crash the tab.

Why does rendering take a while?

Because everything happens on your device. It has to run the AI model, draw the captions on a canvas, and re-encode the video using your local CPU/GPU.

Can I use this for YouTube Shorts?

Yes. The 9:16 format is perfect for Shorts. The 60-second trim preset is ideal.

Can I use this for Instagram Reels?

Yes. The exported MP4 is ready for Instagram. The 9:16 and 4:5 formats are supported.

Do I need to install CapCut or Submagic?

No. This is a completely free, browser-based alternative to Submagic and CapCut for adding auto-captions.

What if my video is already vertical?

You can still use this tool to add auto-captions and stylish text overlays to it.

Does the AI recognize multiple speakers?

It will transcribe everything that is said, but it does not differentiate between speakers (e.g. Speaker 1 vs Speaker 2).

Can I remove the captions?

Yes. If you do not generate captions, the video will render without them.

Why does the AI hallucinate text?

Whisper sometimes generates text during long silences or heavy background noise. You can easily delete these lines in the "Edit text" tab.

Do I need to pay for Whisper?

No. The model runs locally in your browser, so there are no API costs. It is completely free.

Can I add emojis to the captions?

You can type emojis into the "Edit text" tab, and they will appear in the final video.

Does it support 60fps?

The output is 30fps. This is the standard frame rate for Reels and TikTok and keeps file sizes small.

Can I use this commercially?

Yes. You can use the output for client work, brand deals, or your own channel.

What if the browser crashes?

If you upload a very large video, the browser might run out of memory. Try trimming the video first.

When auto-captions work best

Whisper AI is incredible, but it is not magic. Here is how it handles different types of audio.

Audio Type	Result	Notes
Clear English speech (Talking head)	Perfect	Whisper AI is incredibly accurate with clear, direct speech. Expect 95%+ accuracy.
Background music / Noise	Works, with caveats	Heavy background noise can confuse the AI. It may skip words or hallucinate text. Edit the text tab to fix.
Multiple speakers (Podcasts)	Works, with caveats	It will transcribe all speakers, but it will not label who is speaking (Speaker 1, Speaker 2).
Strong accents / Mumbling	Poor	Whisper-tiny is optimized for English, but heavy accents may result in incorrect words.
Non-English languages	Poor	This specific tool uses the English-only Whisper model for maximum speed and accuracy.
Singing / Rap	Poor	ASR models struggle with singing. You will need to type lyrics manually.

Tips for perfect captions

Check for hallucinations
Whisper AI sometimes invents words during silence. Read through the caption lines and delete any empty or hallucinated text.
Video Trimmer
Fix brand names
If a name or brand is spelled wrong, click the "Edit text" tab on the left and correct it before rendering.
Keep captions safe from UI
On TikTok and Reels, the bottom right corner has buttons. Drag your captions to the middle or top to avoid them.
Use the 15s / 30s presets
If you have a long video, use the quick trim buttons to isolate a short highlight.

ToolDeck vs Submagic & CapCut

Submagic and CapCut charge monthly fees, add watermarks, and upload your videos to their servers. ToolDeck is entirely local and free.

Feature	TToolDeck	Submagic / CapCut
Uploads video to a server	No	Yes
Adds a watermark to export	No	Yes
Requires monthly subscription	No	Yes
Free auto-captions included	Yes	No
Inline text editor	Yes	Yes
45+ caption styles	Yes	Yes
Works offline	Yes	No
Browser-based (no install)	Yes	No
Full export resolution limit	1080p	1080p

What you get for free

100% Free Auto-Captions
Submagic charges $20/month for captions. CapCut charges for Pro. ToolDeck gives you AI auto-captions for free, forever.
Whisper AI Local
Powered by OpenAI Whisper running via WebAssembly. Your audio is never uploaded to a server.
Inline Text Editor
AI makes mistakes. Fix typos directly in the editor before rendering. Changes appear instantly in the preview.
45+ Viral Styles
Neon, Glitch, Vaporwave, Comic, Gradient. Instantly apply viral caption styles to your video.
No Watermark
Export a clean 1080p MP4 file. We never stamp our logo on your content.
Original Audio Kept
The original audio track is copied untouched. Your music and voiceover remain intact.

Your video never leaves your device

There is no upload step and no account. The Whisper AI model runs inside your browser using WebAssembly. Your video and audio are never sent to a server. Read how we keep it private.

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