Do uploaded videos leave my computer?

No. The video and subtitle files chosen from your device are decoded, composed, and re-encoded entirely in your browser using WebCodecs. The tool only uses the network when you load a remote video URL.

Which subtitle file formats are supported?

Upload SRT and WebVTT files (.srt, .vtt). You can also create cues manually inside the tool when you do not have a transcript file.

What does "burn subtitles permanently" mean?

Burning means the subtitles are rendered into the video frames, so any player can show them and they cannot be turned off. This is the most compatible way to share captioned video on social platforms that ignore separate caption tracks.

How do I keep timings precise after edits?

When editing in the manual editor, type timestamps directly or use the duration field; the start/end times propagate to the burn step. Re-importing an SRT or VTT file overwrites the current cue list.

Can I keep the subtitles editable later?

Yes. Save a copy of your SRT or VTT before burning. The exported MP4 has the subtitles fused into the picture and cannot be reverted.

Why are my characters showing up wrong?

Older subtitle files may use a non-UTF-8 encoding. Switch the encoding option (for example, Windows-1252 or ISO-8859-1) before re-uploading the file so the parser reads the bytes correctly.

appkiro.com

Video

Add Subtitles to Video

Video

Add subtitles (SRT, VTT) to your video easily. Customize font, size, color, position and style, then burn them directly into MP4.

Read the full guide

1. Select Video

Drag and drop your video here

or click to browse

Supported: MP4, WebM, MOV, MKV
Max file size: 2GB

2. Add Subtitles

Click to upload SRT or VTT

Supported: SRT, VTT

3. Subtitle Settings

Font Family

Font Size

Text Color

Outline Color

Outline Width

Background

Position

Margin Bottom8%

Encoding

Older subtitle files may need a non-UTF-8 encoding to read correctly.

Subtitles are burned into the video frames so any player shows them. Save a copy of your SRT before processing if you want to keep the text editable later.

Preview

Load a video to preview subtitles

Result

Output appears here

File Name

Original Size

Output Size

Resolution

Duration

Subtitles

This tool overlays subtitle text on a video and re-encodes it inside your browser. Source media never leaves your device when uploaded from disk; the WebCodecs API does the heavy lifting locally.

Why burn subtitles into a video?

Many social platforms strip soft caption tracks, mute audio by default, or simply ignore SRT sidecars. Rendering captions directly onto the picture guarantees viewers see them, helps non-native speakers, supports accessibility, and improves silent feed retention.

Step-by-step workflow

Load a video from your device or paste a direct URL.
Upload an SRT or VTT file, or open the manual editor to create cues line by line.
Adjust font, size, color, outline, background, position, and margin until the live preview matches your style.
Open Advanced Options to confirm the subtitle file encoding and keep the burn switch on.
Click Add Subtitles to Video and watch the progress bar. Download the finished MP4 when it appears.

Settings explained

Font Family: Picks the typeface used in the burned video. Common system and web-safe families are listed; the chosen face is also applied to the live preview so what you see matches the export.
Font Size: Pixel size of subtitle text on the output frame. Larger sizes improve readability on small phone screens; smaller sizes work for cinematic shots and dense dialogue.
Text Color: The fill color of subtitle glyphs. White is the most readable default. Pair high-contrast colors with a darker outline to remain legible over busy backgrounds.
Outline / Outline Color: Stroke width and color drawn around each glyph. A two- to three-pixel black outline restores readability when subtitles sit over bright skies, faces, or fast-moving scenery.
Background: Sets the panel behind the captions. None shows only the text, Semi-transparent drops a soft block behind each cue, Solid renders an opaque slab, and Box per line wraps each individual line for short, punchy captions.
Position grid: Picks the corner or edge that subtitles anchor to. The bottom-center cell is the broadcasting standard, while top-center can be useful when on-screen lower-thirds compete for attention.
Margin Bottom: Extra padding from the chosen edge, expressed as a percentage of the video height. Increase the margin when the player UI or logos overlap the subtitle area.
Encoding: Tells the parser how to read the bytes inside an uploaded SRT or VTT file. Modern files use UTF-8; older exports from broadcast tools may need Windows-1252 or ISO-8859-1 to render diacritics correctly.
Burn-in output: Captions are always rendered into the video frames, so any player and any social platform shows them without a separate caption track. Save your SRT or VTT before processing if you want to keep the text editable for later edits.

Manual subtitle editor

Use the manual editor when you have no transcript file. Type a line, set its start time, and click Add Subtitle. Switch to Paste Text to drop a script and let the tool spread the lines evenly across the video duration. Export the result as an SRT for reuse and version control.

Tips for clean captions

Aim for at most two lines per cue with around 32 characters per line. Longer lines force viewers to read instead of watch.
Hold each cue for at least one second and avoid overlap of more than 200 milliseconds between cues.
Test on the smallest screen your audience uses. Phones expose contrast and outline issues that desktops mask.

Frequently asked questions

Do uploaded videos leave my computer?: No. The video and subtitle files chosen from your device are decoded, composed, and re-encoded entirely in your browser using WebCodecs. The tool only uses the network when you load a remote video URL.
Which subtitle file formats are supported?: Upload SRT and WebVTT files (.srt, .vtt). You can also create cues manually inside the tool when you do not have a transcript file.
What does "burn subtitles permanently" mean?: Burning means the subtitles are rendered into the video frames, so any player can show them and they cannot be turned off. This is the most compatible way to share captioned video on social platforms that ignore separate caption tracks.
How do I keep timings precise after edits?: When editing in the manual editor, type timestamps directly or use the duration field; the start/end times propagate to the burn step. Re-importing an SRT or VTT file overwrites the current cue list.
Can I keep the subtitles editable later?: Yes. Save a copy of your SRT or VTT before burning. The exported MP4 has the subtitles fused into the picture and cannot be reverted.
Why are my characters showing up wrong?: Older subtitle files may use a non-UTF-8 encoding. Switch the encoding option (for example, Windows-1252 or ISO-8859-1) before re-uploading the file so the parser reads the bytes correctly.