Subtitle Sync

Fix subtitle timing — auto two-pass sync, offset, drift, and piecewise correction. Everything runs in your browser.

Subtitle File Out-of-sync .srt

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Drop an .srt file here or click to browse

Auto Sync Two-pass: global + piecewise

Upload a reference — either a synced .srt file (any language) or a video/audio file. The app will automatically find the optimal timing correction in two passes: first a global offset + scale, then piecewise block alignment.
Option A: Reference SRT
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Drop a synced .srt (any language)

Option B: Video / Audio File
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Drop MKV, MP4, WebM, etc.

Constant Offset Shift all subtitles

Shift all subtitles by a fixed amount. Positive delays, negative advances.

Linear Drift / Framerate Scale + offset

Corrects gradual drift from framerate mismatch. Scale 1.001 fixes 23.976fps subs on 24fps video.

Manual Sync Points Piecewise correction

Define anchor points with known correct timing. 2+ points for linear, 3+ for piecewise.
Original Time Correct Time

Structural Matching Subtitle-to-subtitle

Upload a synced reference .srt (any language). Matches by structural features (duration, gaps, text length) then computes RANSAC linear fit. For piecewise correction, use Auto Sync instead.
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Drop a reference .srt file (synced to video)