Can I choose which language appears on top?

Yes. In stacked mode, the primary file's text appears on the first line and the secondary file's text on the second line. Swap the file selection order to change which language appears on top.

What delimiter is used in side-by-side mode?

Side-by-side mode joins aligned languages with a pipe delimiter. Stacked mode does not use a separator.

Does the merger preserve formatting from ASS files?

The merger extracts text content from ASS dialogue lines. ASS styling tags (italic, color, positioning) are not preserved in the merged output, since combining styled text from two different ASS files would create conflicts.

Can I merge more than two languages?

This tool merges two files at a time. For three or more languages, merge the first two, then use the output as the primary file and merge with the third language file in a second pass.

What output format should I use?

The merger outputs SRT or VTT. SRT is widely supported by media players and smart TVs; VTT is usually better for web video.

Absolutely. All processing happens client-side in your browser. No subtitle files are ever uploaded to a server. Your content remains entirely on your device.

How does the merger handle multi-line cues?

Each language's cue text is preserved with its original line breaks. In stacked mode, the primary text appears first (possibly multi-line), followed by a line break, then the secondary text. Multi-line cues from both files are maintained in the output.

Can I use this for creating bilingual karaoke lyrics?

LRC can be used as an input, but the merged output is SRT or VTT rather than LRC. Check whether your karaoke player supports the selected output format before using the result for karaoke.

What if the two subtitle files have completely different timing?

If the timing difference is very large (such as subtitles from different video releases), the alignment may produce poor results. Ensure both subtitle files are for the same video version and have reasonably similar timing before merging.

Does the merger support CJK (Chinese, Japanese, Korean) languages?

Yes. The merger preserves UTF-8 text encoding, so CJK characters display correctly in both the primary and secondary files. This is particularly useful for Chinese-English or Japanese-English bilingual subtitles for anime and dramas.

Can I preview the merged output before downloading?

The merged result is displayed in the preview area after processing. You can review the alignment and layout before downloading the final file.

What happens if one file has cues the other does not?

Cues that exist in only one file are included in the output with just that language's text. The missing language's portion is left blank, so the timing structure remains continuous without gaps.

Can I use bilingual subtitles on Netflix or streaming platforms?

Most streaming platforms do not support user-uploaded bilingual subtitles. Bilingual merged files are best for local playback in VLC, MPC-HC, MPV, smart TV media players, and personal media servers like Plex or Kodi.

Bilingual Subtitle Merger

Combine two subtitle files in different languages with automatic timestamp alignment to create clean dual-language subtitles.

Drag & drop your subtitle file here

Drag and drop subtitle files here or click to browse

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

Browser-Based Processing · Files Stay on Device

Core Processing Architecture

Key Features

Engineered for video editors and localization teams. Helps enforce common subtitle timing rules and formatting.

Merge two subtitle files in different languages with automatic timecode alignment

Stacked layout displays one language above the other (original on top, translation below)

Side-by-side layout joins each aligned pair with a visible pipe delimiter

Cues are aligned by their greatest timing overlap, which handles differently segmented translations

Supports SRT, VTT, ASS, SSA, LRC, SBV, TTML, SCC, STL, and SMI input formats

Handles timing gaps gracefully when translations have different cue segmentation

Perfect for language learning: watch with original audio and translation subtitles simultaneously

Client-side processing - your subtitle files never leave your browser

Live Preview & Execution Pipeline

Bilingual Subtitle Merger Live Execution Demo

en_dialogue.srt

READYTrack 1

00:01.000Welcome to the presentation.

00:05.200Let us begin with chapter one.

zh_dialogue.srt

READYTrack 2

00:01.000欢迎来到演讲现场。

00:05.200让我们从第一章开始。

bilingual.srt

READYBilingual

01.000ENWelcome to the presentation.
01.000ZH欢迎来到演讲现场。
05.200ENLet us begin with chapter one.
05.200ZH让我们从第一章开始。

In-Memory Processing

File parsing, mutations, and time shifts for standard tools run in browser memory without sending subtitle files to our servers.

Millisecond Precision

Millisecond-accurate timecode parsing and arithmetic prevent synchronization drift across desktop and web players.

Fault-Tolerant Engine

Automatic multi-encoding detection and syntax sanitization gracefully handle malformed cues and unexpected linebreaks.

Production Workflows

Common Use Cases

Real-world scenarios across video post-production, course transcription, and global localization.

SCENARIO #1

Language Learning

Create bilingual subtitles showing your native language alongside the language you are learning. Watch foreign films with both languages visible for vocabulary building and comprehension.

SCENARIO #2

Translation Verification

Professional translators can verify subtitle translations by viewing both source and target languages side by side, checking timing alignment and text accuracy.

SCENARIO #3

Bilingual Movie Nights

Merge original-language subtitles with translations for bilingual households or international viewing where viewers speak different languages.

SCENARIO #4

Educational Content

Teachers can create bilingual subtitle tracks for educational videos, showing both the original language and a translation for ESL or foreign language classes.

SCENARIO #5

Accessibility Enhancement

Combine SDH (Subtitles for Deaf and Hard of Hearing) tracks with translated subtitle tracks, providing both sound descriptions and language translation in one file.

Execution Pipeline

How It Works

Streamlined end-to-end processing pipeline engineered for speed and precision.

STEP 01

Upload & Import

Select your primary language subtitle file (the original language track).

PHASE 01

STEP 02

Format Analysis

Select your secondary language subtitle file (the translated track).

PHASE 02

STEP 03

Choose a layout

stacked (one above the other) or side-by-side.

PHASE 03

STEP 04

Processing

The merger aligns cues by comparing timing overlap between the two files.

PHASE 04

STEP 05

Verify & Export

Cues are combined into a single bilingual output with both languages visible per entry.

PHASE 05

STEP 06

Delivery

Download the merged bilingual subtitle as SRT or VTT.

PHASE 06

Engine Capabilities

Why Choose AllSubConverter?

Client-Side Privacy

Standard tools run in your browser so standard files are not uploaded to our servers.

Fast Local Parsing

Optimized processing engine parses and converts files directly in your browser.

Generous Batches

Up to 50 MB per file, 200 files or 1 GB total per batch.

Universal Compatibility

Runs in modern browsers across Windows, macOS, Linux, iOS, and Android.

Tool Suite

More Subtitle Tools

Subtitle Format Cleaner

Remove formatting, tags and noise

Subtitle Editor

Edit subtitle content and timings

Subtitle Sync & Timing Calibration

Adjust timing with millisecond precision

Subtitle Merger

Combine multiple subtitle files

AI Subtitle Translator

Translate to 19 built-in target languages

Frequently Asked Questions

The matcher compares cue timing and pairs cues with the greatest time overlap. This is more forgiving than nearest-start-time matching when translated files use slightly different cue segmentation.

Yes. The merger handles mismatches by pairing cues with the greatest timing overlap. Cues without a match in the other file are included with the available language only.

Yes, completely free with no sign-up, no watermarks, and files up to 50 MB each. All processing happens locally in your browser.

Stacked layout shows the primary cue on the first line and the secondary cue below it. Side-by-side layout puts both languages on one line, separated by a visible pipe delimiter. Choose stacked for readability, side-by-side for compact display.

Both files can use any supported input: SRT, VTT, ASS, SSA, LRC, SBV, TTML, SCC, STL, or SMI. You can mix formats. The merged output is SRT or VTT.

The alignment uses greatest timing overlap. For professionally translated subtitle pairs, alignment is usually reliable. Independently created subtitles with substantial timing differences may still produce imperfect matches.

Ready to convert your subtitles?