Free Add Subtitles to Video Online
Import SRT/VTT, generate AI captions, and style them. No upload, no watermark, no sign-up.
A complete subtitle editor in your browser. Import an existing SRT or VTT file, auto-generate captions with AI, or type them manually. Customize the font, color, and outline, then render an MP4 with the text perfectly burned in. Your videos are never uploaded. No sign-up, no watermark.
- SRT & VTT Import
- AI Auto Captions
- Burn-in Hard Subs
- 40+ Subtitle Styles
- No upload
- No watermark
How do I add subtitles to a video online for free?
Drop your video into the editor above, open the AI Captions and Subtitles tab, and press Generate Captions (for English speech). If you already have a subtitle file, press Import SRT / VTT file. Style the text clips on the timeline, then hit Export to render an MP4 with the subtitles burned in. Everything runs in your browser, so nothing is uploaded, and the export has no watermark.
- Price
- Free, no credits and no watermark
- Account required
- No
- Video uploaded to a server
- No, rendered in your browser
- Import formats
- SRT and VTT files (ASS/SSA not supported)
- Export formats
- MP4 with burned-in text, or SRT/VTT files
- AI caption language
- English speech (Whisper, on-device)
- Subtitle styling
- 40+ presets, custom fonts, outline, and boxes
- Input video formats
- MP4, WebM, MOV, MKV, JPG, PNG
- Max export resolution
- Up to 4K at 60 fps
- File size limit
- 1 GB per imported file
- Best browsers
- Chrome and Edge on desktop
- Not included
- Cloud translation, ASS/SSA subtitle formats
What is the ToolDeck subtitle editor?
ToolDeck Add Subtitles to Video is a free, browser-based tool that permanently burns text into your video files. It supports importing .srt and .vtt subtitle files, generating English captions with on-device AI, and creating fully custom text styles. It uses WebCodecs to render the final video locally on your GPU, ensuring privacy and speed.
It is best for social media creators who need bold, on-screen text, educators adding captions for accessibility, and anyone who wants to hardcode subtitles without paying a monthly subscription.
How to add subtitles in 3 steps
- 1
Import your video
Drop your MP4, WebM, or MOV file into the editor. The video is loaded into your browser and is never uploaded to a server.
- 2
Add your subtitles
Either click "AI Captions" to auto-generate text, click "Import SRT/VTT" to upload a file, or click "Add Caption" to type manually at the playhead.
- 3
Style and Export
Use the AI Captions tab to customize font, color, and size. Press Export, choose GPU or CPU rendering, and download the MP4 with burned-in subtitles.
Professional subtitle features, free
Import SRT and VTT files
Already have subtitles from YouTube, Rev, or another editor? Import your .srt or .vtt file and instantly overlay it on your video. The editor parses timecodes and syncs them to your timeline automatically.
Burn-in hardcoded subtitles
Unlike soft subtitles that can be turned off, "burned-in" subtitles are rendered directly into the video pixels. They appear exactly the same on TikTok, Instagram, YouTube, or any offline player.
AI Auto Captions (English)
No SRT file? Let Whisper AI generate subtitles for you. It listens to English speech and generates perfectly timed caption clips on your timeline, all without uploading your audio to a server.
40+ Professional Styles
Make your subtitles pop. Choose from classic white text with a black box, bold yellow, neon glow, or animated pop-in styles. Adjust font, outline, background box, and position.
Edit subtitles word-by-word
Generated text is not always perfect. Click any subtitle clip on the timeline to edit the text, fix typos, adjust the start/end timing, or split a long sentence into multiple shorter clips.
Export SRT or VTT formats
Need subtitles for YouTube? Generate or type your captions, then export them as an SRT or VTT file from the Export menu. Only the caption track is exported for a clean file.
Any aspect ratio
Create subtitles for 16:9 YouTube videos, 9:16 TikTok shorts, or 1:1 Instagram posts. The canvas adjusts so your text always fits the safe zone and never gets cut off by platform UI.
MP4 export, no watermark
Render your video with the subtitles permanently embedded into the MP4 file. No watermarks, no credits, and no sign-up. Export up to 4K resolution using your own GPU or CPU.
What you can make with this tool
YouTube accessibility
Add subtitles for the deaf and hard of hearing, or for viewers watching without sound. Export an SRT file to upload directly to YouTube Studio.
TikTok and Reels retention
Add bold, animated captions to keep viewers scrolling. 80% of social media videos are watched on mute; subtitles force viewers to stay engaged.
Foreign language films
Translate an SRT file using a translation tool, then import the translated SRT into the editor and burn it into the video.
Corporate training
Ensure company videos meet accessibility compliance standards by hardcoding subtitles into internal training and HR videos.
Online courses
Help students follow along with lectures. Subtitles are crucial for technical terms, names, and non-native speakers.
Social media clips
Cut a long video into shorts and keep the subtitle text large and centered for perfect mobile visibility.
Subtitle editor FAQ
Detailed answers about SRT/VTT files, AI generation, styling, burn-in, and privacy.
Free, privacy and sign-up
How do I add subtitles to a video for free?
Drop your video into ToolDeck, open the AI Captions tab to generate them, import an SRT file, or type them manually. Style the text, then press Export. The subtitles will be burned into the video. It is free, requires no account, and adds no watermark.
Is it really free, with no hidden limits?
Yes. There are no credits, no daily caps, and no paywalls. The limits are purely technical: browser memory, a 1 GB limit per imported file, and your device’s processor speed for rendering.
Does it upload my video or subtitles?
No. The editing, AI transcription, and final rendering all happen locally in your browser using WebAssembly and WebCodecs. Your files never touch our servers.
Do I need to create an account?
No. Just open the page and start editing. There is no login, email wall, or trial period.
SRT, VTT and file formats
Can I import an SRT or VTT file?
Yes. Open the AI Captions tab and click "Import SRT / VTT file." The editor will parse the timecodes and place your text on the timeline. Any language inside the file will be displayed perfectly.
Can I export subtitles as SRT or VTT?
Yes. After generating or typing captions, open the Export menu and click "SRT" or "VTT". This downloads a clean text file, perfect for uploading to YouTube.
Does it support ASS or SSA subtitle files?
No. The editor currently supports only SubRip (.srt) and WebVTT (.vtt). You can convert ASS/SSA to SRT using a free online converter first.
What is the difference between soft and hard subtitles?
Soft subtitles are separate tracks (like an SRT file) that the viewer can toggle on or off. Hard subtitles (burned-in) are permanently rendered into the video pixels. ToolDeck excels at hard subtitles for social media.
AI Auto Captions
How do the AI auto captions work?
We use OpenAI’s Whisper model, which runs locally in your browser. It listens to English speech, figures out what is being said, and creates timed text clips on your timeline. No audio is uploaded.
Which languages do the AI captions support?
The on-device model is optimized for English. Accuracy for other languages is not guaranteed. For foreign languages, you should import an SRT file.
How accurate are the AI captions?
Very accurate for clear audio. However, background music, heavy accents, and technical jargon can cause errors. Always review the text and fix any mistakes by clicking the caption clip on the timeline.
Styling and syncing
Can I change the font, color, and size?
Yes. In the AI Captions tab, you have full control over the font family, size, color, outline thickness, background box, and even glow effects. You can apply styles to one caption or the entire track at once.
How do I sync subtitles with the audio?
If you imported an SRT, timing is automatic. If you are typing manually, move the playhead to where the speech begins, click "Add Caption," and drag the edges of the text clip to adjust when it appears and disappears.
Can I split a long subtitle into two?
Yes. Place the playhead over a caption clip and press S to split it. You can then edit the text of each half independently.
Quality, export and limits
What resolution can I export?
You can export up to 4K at 60 fps if your device has enough processing power. For TikTok, 1080x1920 at 30 fps is usually the best balance of quality and file size.
Why are my exported subtitles blurry?
Subtitles are rendered at the same resolution as your export. Make sure you are not stretching a small video to 4K. Exporting at a lower resolution (like 1080p) often results in sharper-looking text.
What happens if my browser crashes during export?
Long videos with many effects use a lot of memory. If the tab crashes, try exporting at a lower resolution, closing other browser tabs, or splitting the video into smaller parts.
Browser support
Which browser is best?
Chrome and Edge on desktop are strongly recommended. They support WebCodecs, which allows for fast hardware-accelerated rendering. Firefox works, but may be slower.
Does it work on mobile phones?
The editor will load on iOS and Android, but editing complex videos and rendering might be slow due to mobile memory limits. It is best used on a desktop or laptop.
What this editor does well, and where it is limited
We prioritize privacy and zero-cost, which means some heavy cloud tasks are not available.
| Task | Result | Notes |
|---|---|---|
| Importing clean SRT or VTT files | Works well | Parses timecodes and text perfectly, creating one editable clip per line. |
| Burning text into the video | Works well | Text is drawn at the exact resolution of your export, ensuring crisp edges. |
| AI auto captions for English | Works well | Fast and accurate for clear audio, but always review names and technical jargon. |
| AI auto captions for other languages | Not supported | The on-device model is English only. For other languages, import an SRT/VTT file. |
| Translating SRT to another language | Not supported | The editor does not translate text. Use ChatGPT or a translation service first. |
| ASS / SSA subtitle formats | Not supported | Only SubRip (.srt) and WebVTT (.vtt) are supported. Convert files first. |
| Very long SRT files (1000+ lines) | Memory heavy | Can slow down the timeline. Split very long videos into parts if the tab crashes. |
Tips for perfect subtitles
Position in the safe zone
For TikTok/Reels, keep text away from the bottom 20% and right edge, where the app buttons sit.
Use high contrast
A thick outline or a solid black box behind white text is the most readable combination on any background.
Review AI transcription
Auto-captions are great but not perfect. Read through the text clips and fix any misheard words before exporting.
Keep the SRT file
Even if you burn subtitles in, export the SRT too. It is useful for YouTube SEO, accessibility, and future edits.
ToolDeck vs cloud subtitle tools
Cloud tools charge monthly subscriptions or watermark your video. ToolDeck processes everything locally and charges nothing.
| Feature | ToolDeck | Typical cloud editors |
|---|---|---|
| Your video is uploaded to a server | Never | Usually yes |
| Watermark on export | None | Varies by plan |
| Sign-up needed | Not required | Often |
| Daily limits or caption caps | None | Usually yes |
| Import SRT and VTT files | Yes | Varies by plan |
| AI auto captions | Yes, English (on device) | Yes |
| Burn subtitles into the video | Yes | Yes |
| Export subtitles as SRT/VTT | Yes | Varies by plan |
| Custom subtitle styling (fonts, colors) | Yes | Varies by plan |
| Works offline after loading | Editing yes, AI model needs download | Usually no |
General comparison. Individual products differ, and features, limits and pricing change.
Use media you have the right to edit
Only add subtitles to footage, music and images you own or are licensed to use. Using someone else's work without permission can infringe copyright.
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Your videos and audio never leave your device
There is no upload step and no account. Subtitle styling, AI transcription, and final rendering happen in your browser. You can check this yourself: open your browser developer tools, go to the Network tab, then generate captions and export the video to verify nothing is uploaded. Read how we keep it private.