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Subtitle Duplicate Remover

Fast. Private. Perfect.

Upload a subtitle file and find every repeated line. Remove adjacent duplicates from auto-caption glitches, exact repeats, and fuzzy near-duplicates, then download a clean file.

Private & Secure
Blazing Fast
Free & Unlimited

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SRT, VTT, ASS, SSA, LRC, SBV, TTML, SCC, STL, SMI, TXT

100% LocalNo UploadSecureInstant

How It Works

1

Upload your subtitle file in any supported format.

2

Choose which duplicate types to scan for and adjust the matching options.

3

The tool parses every cue and normalizes the text for comparison.

4

Review the list of flagged duplicates with their timestamps and reasons.

5

Click remove to delete all duplicates and download a clean, renumbered file.

Why Choose AllSubConverter?

Your Privacy Matters

Everything runs in your browser. Your files are never uploaded.

Lightning Fast

Optimized processing engine converts files in seconds.

Truly Unlimited

No file size limits. No daily limits. Completely free.

Works Everywhere

Works on Windows, Mac, Linux, iOS, Android - any modern browser.

Key Features

Detects three duplicate types: adjacent repeats, exact duplicates, and fuzzy near-duplicates
Adjacent detection removes the stuttering back-to-back repeats common in Whisper and auto-caption output
Near-duplicate mode uses Levenshtein similarity to catch lines that differ by only a word or punctuation
Normalizes text before comparing so you can ignore case, whitespace, and inline tags independently
Adjustable similarity threshold and minimum line length to prevent false positives
Preview every flagged line with its timestamp and reason before removing anything
Exports a clean SRT file with duplicates removed and numbering resequenced
100% browser-based - no file uploads, complete privacy

Common Use Cases

Whisper Auto-Captions

OpenAI Whisper often repeats the same line twice in a row. This tool removes those stuttering duplicates instantly.

Translation Cleanup

When copy-pasting translated lines, duplicates slip in. Scan for exact and near-duplicates to clean them up.

Merged File Repair

After merging two subtitle files, repeated cues can overlap. Detect and remove them in one pass.

Broadcast QC

Quality-control teams flag duplicated lines before delivery. This tool automates the detection step.

Frequently Asked Questions

A subtitle duplicate is a cue whose text is identical or nearly identical to another cue. Adjacent duplicates appear back to back (common in auto-captions), while exact and near-duplicates can appear anywhere in the file.

No. Only the duplicate cues are removed. The remaining cues keep their original timecodes and the output is renumbered sequentially.

Yes, completely free with no registration, no watermarks, and no file uploads.

Near-duplicate mode computes the Levenshtein edit distance between two lines and converts it to a similarity ratio. If the ratio meets your threshold (default 92%), the line is flagged as a duplicate.

SRT, VTT, ASS, SSA, LRC, and SBV. The tool auto-detects the input format and outputs a clean SRT file.

Yes. Everything runs client-side in your browser. No subtitle data is ever sent to a server.

Ready to convert your subtitles?

Upload a subtitle file and find every repeated line. Remove adjacent duplicates from auto-caption glitches, exact repeats, and fuzzy near-duplicates, then download a clean file.