Subtitle Sync Editor — Edit & Export .srt/.vtt
Visually adjust subtitle timestamps, preview with video, and export corrected .srt or .vtt files — all in your browser.
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What is the Subtitle Sync Editor and why it matters
The Subtitle (.srt) Sync Editor is a lightweight browser tool designed to give creators, editors, and site owners fine-grained control over subtitle timing without requiring professional video suites. It parses standard .srt and .vtt files, renders caption text on a visual timeline, and lets you drag and resize caption blocks to correct start and end timestamps while previewing changes directly against your video. Because the tool runs completely in the browser, there is no upload to a third-party server — subtitle accuracy is edited locally and exported back to your device as corrected .srt or .vtt files.
For bloggers, course creators, and businesses publishing tutorials, lectures, and product videos, accurate subtitles mean better accessibility, higher engagement, and improved video SEO. Search engines and platforms increasingly rely on accurate captions to index video content and surface it to users searching for text-relevant queries. This tool enables quick subtitle fixes — from synchronizing a narrator’s audio drift to splitting long captions for readability — saving hours compared to re-exporting from desktop editors.
Technically-minded site owners will appreciate that the tool supports both SRT and WebVTT formats (the two most common caption standards), makes it easy to edit caption text inline, and exports files in the proper timestamp formats. Use-cases include: fixing auto-generated captions, creating translated subtitles, polishing captions for social-sharing clips, or aligning captions for audio-drift correction.
Who should use it? If you create or publish video content — bloggers, small studios, e-learning providers, marketers, or hobbyists — this tool helps you deliver accessible, SEO-friendly video experiences without installing software. It’s ideal when you need to make fast time-code adjustments, iterate on caption phrasing, or generate fresh .srt/.vtt files for upload to YouTube, Vimeo, or your CMS.
Browser-only notice: This tool runs 100% in your browser. Your video and subtitle files are processed locally — nothing is uploaded or stored.
Subtitle (.srt) Sync Editor — Tool
Edit captions
Frequently Asked Questions (FAQ)
Q1 — What subtitle formats does this tool support?
A: The Subtitle Sync Editor supports two main caption standards: SubRip (.srt) and WebVTT (.vtt). When you upload a .srt or .vtt file, the parser converts timestamps and text into an editable list. You can then edit text and timestamps and export back to either .srt or .vtt. The tool also handles typical variations in timestamp formatting (commas vs dots for milliseconds) and will normalize them for export. This support makes it simple to fix captions created by automated services or to refine translated subtitle files.
Q2 — How does the timeline editing work?
A: Once a video is loaded (uploaded or via a direct URL), the timeline uses the video's duration to map caption start and end times to a horizontal, visual canvas. Each caption appears as a draggable block: drag the entire block left/right to shift both start and end times, or drag the left/right handles to adjust start or end individually. Changes update the timestamp display and the editable caption textarea so you can fine-tune text and timing. Clicking a caption will jump the video to that caption's start time, allowing quick visual verification. The interface was designed for fast iteration: large handles, clear labels, and keyboard-friendly controls.
Q3 — Is my video or subtitle data uploaded to a server?
A: No. All processing takes place locally in your browser. Files you select using the file inputs are read with the FileReader API and never sent to any server. The short disclaimer under the tool reiterates this: “This tool runs 100% in your browser. Your text is never collected or stored.” This approach protects sensitive content and avoids privacy concerns while making the tool fast and reliable.
Q4 — Can I fix auto-generated captions (e.g., YouTube) with this tool?
A: Yes. Download the auto-generated captions from the host (YouTube provides caption downloads in .vtt/.srt), then load the file into the editor. The timeline helps you correct errors caused by misalignment or audio drift: shift captions, split long captions, or edit text inline. After improvements, export the corrected file to re-upload to your platform or upload to your CMS. This workflow removes the need for heavy desktop suites for small sync fixes.
Q5 — How precise can I be with timestamps?
A: The editor supports millisecond precision for SRT (hh:mm:ss,ms) and WebVTT (hh:mm:ss.mmm). The timeline maps position based on the video's exact duration, and dragging updates timestamps in real time. For very fine adjustments, you can also edit timestamps manually using the caption time fields shown next to each item. The "Export" function will format times to the correct spec for the chosen format.
Q6 — Can I edit caption text and split or merge captions?
A: Yes. Each caption item shows a textarea where you can change the caption text, break lines, or correct typos. To split a caption, place the caret at the split point, copy the text into a new caption, and adjust timestamps. To merge, combine texts in one caption and extend its end time. The tool focuses on direct editing rather than automated splitting rules, giving you control for clean, readable captions.
Q7 — Does the tool support multiple languages and character sets?
A: Yes. The editor handles Unicode text so you can edit captions in any language supported by the browser. Make sure your exported file encoding is UTF-8 when uploading back to platforms — the exported Blob created by the tool uses UTF-8 by default to ensure correct characters for languages such as Hindi, Arabic, Japanese, etc.
Q8 — What platforms accept exported .srt/.vtt files?
A: Most major platforms support .srt and/or .vtt, including YouTube, Vimeo, Facebook, and most CMS video players. YouTube accepts both but prefers WebVTT for some features; Vimeo uses captions or closed-caption files. When in doubt, check platform documentation — the editor gives you both formats to match the platform's requirement.
Q9 — Can I use this editor to create subtitles from scratch?
A: Yes — you can create an empty set and add captions manually. Use the "Add caption" control (or duplicate existing rows), set start/end times by typing or dragging, and paste the subtitle text. While the editor is optimized for syncing existing captions, adding captions manually is straightforward for short projects.
Q10 — How do I export and use the corrected subtitle files?
A: Click Export .srt or Export .vtt to download a file containing your current captions. The tool formats timestamps correctly and encodes the file in UTF-8. After downloading, upload the file to your video hosting platform’s subtitle/caption upload area, or include it in your web player as a track element for HTML5 video.
Q11 — Troubleshooting: Why do caption blocks sometimes overlap on timeline?
A: Overlaps happen if start/end times are too close or were imported from noisy auto-generated captions. Use the "Auto-trim Overlaps" button to nudge end times before starts. You can also manually adjust handles to remove overlap. The editor enforces visual spacing but doesn't silently delete content — edits remain explicit so you control how captions are shortened or split.
Q12 — Are there keyboard shortcuts or accessibility features?
A: The tool is keyboard friendly: tab through inputs and use arrow keys in time or caption fields. Clicking a caption jumps the video to that caption's start time, and all interactive elements have large targets for easy use on touch devices. The color palette, contrast, and font sizes are optimized for accessibility on dark backgrounds per ToolNestLab guidelines.
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