VIDEO UTILITIES / PRIVATE STUDIO

Subtitle Synchronizer

Fix subtitles that start too early, drift out of sync, or use the wrong frame rate. Edit, preview, and export SRT or VTT files — without uploading anything.

100% local processing

Drop your SRT or VTT file here

Or select a subtitle file · UTF-8 · Up to 12 MB

Want to try the editor first?

CURRENT FILE——

—Cues

—End time

—Overlaps

Timing tools

Choose a correction, preview its impact, then apply. Shift can target selected cues.

Move every subtitle earlier (negative) or later (positive). Keep durations unchanged unless a cue crosses time zero.

Time offset (milliseconds)

Apply shift to

Select cues using checkboxes in the subtitle table. Other cues remain unchanged.

If timing moves before 00:00

Trimming keeps the portion after 00:00; removed or clipped cues are always reported.

History

No edits applied.

Video sync preview Optional

Compare text timing with a video kept on your device.

▷

No video added

Import a local video to check subtitle timing visually.

Preview at

Subtitle timeline

Edit individual cues, detect overlapping captions and jump to exact timestamps.

Select / #	Start → End	Text	Actions

Ready. All subtitle processing stays in your browser.

Fix subtitle synchronization online

Shift SRT and VTT subtitles

A positive time offset moves subtitles later; a negative offset brings them earlier. Use exact milliseconds for fine adjustments without manually editing every caption.

Convert frame rates correctly

When subtitles were timed for footage at a different playback speed, multiply timestamps by the source-to-target frame-rate ratio. Frame-rate changes alter both cue position and duration, unlike a fixed delay.

Correct progressive drift

If the start matches but subtitles are late by the end, align two known positions. A linear two-point mapping corrects constant speed drift. Multi-point sync handles piecewise drift, but cannot discover missing scenes automatically.

Supports UTF-8 SRT and WebVTT text subtitles, up to 12 MB and 25,000 cues. Exports preserve millisecond timing. No automatic speech recognition, subtitle translation, embedded subtitle extraction, or video re-encoding. Local video previews depend on formats your browser can decode.

Using Subtitle Synchronizer

Correct subtitle timing with global or selected shifts, frame-rate conversion or piecewise drift anchors, and review the cues over local video before exporting.

Workflow

Import SRT or WebVTT and inspect cue order

apply a global shift, selected shift, frame-rate correction or piecewise anchors and check negative times and overlaps

preview over local video, then export SRT, VTT or timing CSV.

Example

If subtitles drift gradually, place two or more anchors at known points, apply a piecewise correction, preview early and late cues against the video, then export a new subtitle file.

Limits and data handling

This is a manual timing editor, not speech recognition or audio-based alignment. Piecewise mapping is monotonic and extrapolates the first and last segment outside anchors. Review negative-time clipping and cue overlaps. SRT and VTT metadata differ, and NOTE associations are format-specific. The overlay is a local preview, not burned-in video output.

FAQs

Can it automatically detect speech and align captions?

No. Timing corrections are manual; there is no speech recognition or acoustic alignment.

Does export burn subtitles into the video?

No. It exports subtitle or timing files; the local overlay is only a preview.