SoftSub: Add Subtitles to Any Video — Auto-Sync, SRT & Translate

Add subtitles to any video: search, load .srt/.vtt/.ass, sync and translate. Auto-sync verifies itself before it moves your timing.

SoftSub is a Chrome extension that adds subtitles to any HTML5 video. It finds a subtitle for what you're watching, overlays it on the video, syncs it to the audio and can translate it as you watch. It works on small sites, embedded players, personal media servers and video files opened in the browser — not just one streaming service. FIX SUBTITLES THAT ARE OUT OF SYNC Subtitles that arrive late or early — a subtitle delay — are usually off by one fixed amount, sometimes with a gap that grows over the film. SoftSub listens to the video's audio, builds a picture of where speech starts and stops, and matches that against the subtitle's own timing — the same approach as ffsubsync. It usually settles within 30 seconds of playback and lands the words on the speech. The important part is what it does when it isn't sure: nothing. A wrong correction applied confidently is worse than none, so SoftSub verifies a result before using it and refuses rather than guessing. It also corrects framerate drift (23.976 / 24 / 25 fps), the reason subtitles that start out fine slide out of sync an hour later. In our recorded demo the subtitle loaded 3.5 seconds late; SoftSub listened for 28 seconds, verified the match and moved the captions by 3.73 seconds. Prefer to do it by hand? Nudge with Alt+, and Alt+. (100 ms a step) or type an offset in the ⋯ menu that sits on the caption itself — the only way to adjust timing in fullscreen. ADD SUBTITLES TO A VIDEO THAT HAS NONE Open the popup and SoftSub searches Podnapisi, Addic7ed, OpenSubtitles and SubDL for the title you're watching, with no API keys or accounts to set up. Pick a result and it loads over the video. SoftSub remembers the subtitle and your timing for that video and brings both back when you return. LOAD YOUR OWN SRT, VTT OR ASS FILE Choose a .srt, .vtt or .ass file in the popup and it plays over the video. Drag the caption anywhere on the picture; set the font, size, colour and background. When the timing is right, export the corrected .srt to keep. TRANSLATE SUBTITLES WHILE YOU WATCH Live translation into 100+ languages, shown under the original line or on its own — for following a language you only half know. Only the subtitle text is sent to the translation service, never the video. WHO IS ON SCREEN (SOFTSUB PRO) Turn on the Cast info panel and a panel headed by the film or episode's title shows who's in the scene: photos, actor and character names, and a person card when you tap a tile. A second opt-in adds on-device face recognition that marks who is on screen right now. That analysis happens entirely on your computer; no video frame ever leaves it. Both are off by default and do nothing until you enable them. KEYBOARD SHORTCUTS Alt+S auto-sync · Alt+, subtitles earlier · Alt+. subtitles later · Alt+V show or hide FREE VS SOFTSUB PRO Free, forever: subtitle search from Podnapisi, Addic7ed, OpenSubtitles and SubDL (10 downloads a day from the last two), loading your own subtitle files, and everything about displaying, positioning, styling, manually timing and exporting a subtitle. SoftSub Pro — $1/month for 2 computers, or $15/month for 5, after a 7-day trial with no card: • Unlimited subtitle downloads • Automatic sync • Live translation (500,000 characters/month) • Cast info panel, with optional on-device face recognition Cancel any time from the extension's settings; Pro stays on until the end of the paid month. QUESTIONS PEOPLE ASK Why are my subtitles late? Usually the subtitle was made for a different cut or release of the video, so every line is off by the same few seconds. Sometimes the framerate differs too, so the gap grows as the film goes on. Auto-sync measures both against the audio and corrects them; the ⋯ menu lets you nudge by hand. Does it work on local video files? Yes. Open the file in a Chrome tab and SoftSub treats it like any other HTML5 video: search for a subtitle, load your own, sync, translate, export. Does it work on every website? It works wherever the page plays video in a standard HTML5 player, including players inside frames. If a site draws video some other way, SoftSub has no video to caption. Is auto-sync free? Installing is free, and search, your own files, styling, manual timing and export stay free. Auto-sync, live translation and the cast panel are SoftSub Pro: 7-day trial, no card, then $10/month for 2 computers or $15/month for 5. Does SoftSub record or upload what I watch? No. Sync listens to the audio inside your browser and face recognition runs on your computer; neither sends anything anywhere. There are no accounts, ads, analytics or tracking. When translation is on, the subtitle text — and only that — goes to the translation service. Can I keep the corrected subtitle? Yes. Press Export and the .srt is saved with the corrected timing. PRIVACY No accounts, no advertising, no analytics, no tracking. Video and audio never leave your device — sync and face recognition both run locally. When live translation is on, the subtitle text (and only that) is sent to a translation service. Full policy: https://softsub-api.softsub.workers.dev/privacy WHAT'S NEW 1.0.2 (September 2026): the listing is available in eleven languages, and SoftSub asks once — after your first verified sync — whether you'd rate it. The interface itself is in English. SoftSub is developed by Synced Media Solutions.