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Add Subtitles to Video

Burn SRT captions permanently into any video, free and private

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100% private. Your file is processed locally in your browser with WebAssembly — it is never uploaded to a server, stored, or seen by anyone.

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Add Subtitles to Video burns an SRT subtitle file permanently into your footage, so the captions become part of the picture and display on any player, social platform, or device, with no separate subtitle file required. Because the text is hardcoded directly onto the frames, it survives re-uploads to Instagram, TikTok, and other sites that strip soft caption tracks, guaranteeing viewers see your words even when they watch on mute.

Everything runs locally in your browser using WebAssembly (ffmpeg.wasm), so your video and SRT file are processed on your own device and never uploaded to any server. This makes the tool a fast, free, signup-free option for creators, marketers, educators, and accessibility teams who need permanently captioned MP4s while keeping sensitive or unreleased footage completely private.

Why use this tool

Captions that survive every platform

Because subtitles are hardcoded onto the frames, they cannot be stripped or toggled off, so they display correctly when re-uploaded to TikTok, Instagram, LinkedIn, and YouTube where soft caption tracks often get lost.

Fully private, nothing uploaded

Your video and SRT file are processed entirely on your device with WebAssembly, never touching a server, which keeps unreleased, client, or personal footage confidential.

Plays everywhere with no separate file

The output is a single self-contained MP4, so there is no need to ship a separate subtitle file or rely on a player that supports SRT, captions just appear.

Free with no signup or watermark

Add subtitles to unlimited videos at no cost, with no account, no watermark on your footage, and no feature paywalls.

How to use the Add Subtitles to Video

  1. Add your video

    Select or drag in the video file you want to caption, such as an MP4, MOV, or WebM clip.

  2. Add your SRT subtitle file

    Upload the matching SRT file containing your captions and timestamps so it lines up with the video's dialogue.

  3. Confirm the output

    Review that the video and subtitle pairing is correct; the tool will produce a permanently captioned MP4 with H.264 video.

  4. Burn in the subtitles

    Start processing and let ffmpeg.wasm re-encode the video locally in your browser, overlaying the subtitle text onto every frame.

  5. Download your captioned video

    Save the finished MP4 with hardcoded subtitles, ready to play on any device or upload to social platforms.

Popular use cases

  • A creator hardcodes captions into a vertical clip so it reads clearly for the large share of viewers who watch social videos on mute.
  • A marketer burns branded subtitles into a product demo before uploading to multiple platforms, ensuring the captions can't be stripped on re-upload.
  • An educator permanently embeds subtitles in a lecture recording so students can follow along on any device without enabling a caption track.
  • An accessibility team adds always-on captions to internal training videos to meet inclusion requirements for deaf and hard-of-hearing employees.

Frequently asked questions

Is the Add Subtitles to Video tool free?
Yes, it is completely free with no signup, account, watermark, or usage limits. You can burn subtitles into as many videos as you want at no cost. The tool is funded as part of the ClipTools.net suite of free browser-based video utilities.
Are my video and subtitle files uploaded to a server?
No. All processing happens locally in your browser using WebAssembly (ffmpeg.wasm), so your video file and SRT file never leave your device. Nothing is uploaded, stored, or transmitted to any server, which makes it safe for confidential, unreleased, or personal footage.
What is the difference between burned-in and soft subtitles?
Burned-in (hardcoded) subtitles are rendered permanently onto the video frames as part of the picture, so they always display and cannot be turned off. Soft subtitles are a separate selectable track viewers can toggle, but many platforms strip them on upload. This tool burns subtitles in permanently so they show on every player and survive re-uploads to TikTok, Instagram, and similar sites.
What file formats does it support?
It accepts standard video files such as MP4, MOV, WebM, MKV, and AVI for the video input, plus an SRT (SubRip) file for the captions. The output is an MP4 with H.264 video so it plays everywhere. SRT is the most common subtitle format and is exported by tools like YouTube, Premiere, CapCut, and most auto-caption services.
Is there a file size limit?
There is no hard server-imposed limit because processing happens on your own machine, but practical size depends on your device's available RAM since the video is loaded into browser memory. Short and medium clips up to a few hundred megabytes work smoothly on most computers; very large or long files process more slowly and use more memory. Using a desktop browser gives the best results for big videos.
Will burning in subtitles reduce my video quality?
Burning subtitles requires re-encoding the video, so there is a small, usually unnoticeable quality change typical of any H.264 re-export. The tool uses sensible encoding settings to keep the result visually close to the source while overlaying crisp, legible text. The audio track is preserved without re-compression where possible.
Do I need to create the SRT file myself, or can the tool generate captions?
This tool burns an existing SRT file into your video; it does not auto-generate captions from speech. You can create an SRT with auto-transcription tools, a video editor, or by hand, then bring it here to hardcode it. ClipTools.net offers separate transcription tools if you need to generate a subtitle file first.
Can I control how the subtitles look, like font size or position?
Subtitles are rendered with clear default styling sized for readability across devices, including standard bottom-center placement. Basic appearance follows the SRT and the tool's burn-in defaults, so you get legible white text suitable for most videos without manual styling. For heavy custom styling, format your SRT or pre-style captions in a dedicated editor before burning.

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