English subtitles on Japanese videos with no captions (free)

Published: 2026-09-15 ・ Updated: 2026-11-03

Works in Chrome or Edge on a computer (Firefox: through a microphone or audio input; the add-on covers YouTube and Twitch; not on phones). Japanese ⇄ English only.

You found a Japanese video you want to watch: a talk, a game playthrough, a vlog, a commentary video. But there are no English subtitles, and when you open the caption menu there is nothing to translate from.

This guide shows how to get English subtitles on a recorded Japanese video playing in your browser, even when it has no captions at all. It is free and you do not need to install anything.

In short: LiveSub makes subtitles from the video's audio, so the video does not need captions. Add the free LiveSub extension for Chrome or Edge on your computer, press its icon on the video's tab, and set “Translate from / to” to Japanese → English in the LiveSub tab that opens. The subtitles appear over the video, with no sharing dialog. Without the extension, open LiveSub in another tab and share the video's tab instead.

Open LiveSub and try it

Why captions do not matter

Automatic caption translation on video sites works by translating captions that are already attached to the video. If a video has no captions, there is nothing to translate.

LiveSub works differently. It listens to the audio playing in the tab and makes subtitles from that. So it does not matter whether the video has captions, or which site it is on.

Everything runs on your own computer. The Japanese speech is recognised by a model running inside your browser, and the translation uses Chrome's built-in on-device translator. Your audio is not uploaded anywhere.

What you need, and good videos to try

• Chrome or Microsoft Edge on a computer. In Firefox, LiveSub listens through a microphone or a loopback audio input (such as Windows Stereo Mix); on YouTube and Twitch, LiveSub for Firefox turns the video's audio into subtitles directly. Safari uses the same input method but is untested
• Not a phone or tablet. Mobile browsers cannot share tab audio
• A one-time download of the speech recognition model. For Japanese, the Balanced setting is about 670MB. After the first time, it is loaded from your browser's storage

No account, no extension, no payment, and no time limit.

Using Firefox? Firefox cannot share a tab's audio, so LiveSub listens through a microphone or an audio input instead. Open LiveSub in Firefox, play the video in another tab, and press "Start (mic or audio input)" on the LiveSub page. Allow microphone access when the browser asks. If your computer has a loopback input (such as Windows Stereo Mix), LiveSub picks it automatically; otherwise it listens through the microphone to the sound from your speakers (headphones will not work). There is no sharing dialog. On YouTube and Twitch, LiveSub for Firefox turns the video's audio into subtitles directly: press "Add to Firefox — it's free" to install it, play the video in another tab, and press "Start (YouTube / Twitch tab)"; the subtitles appear over the video.

Good videos to try: YouTube videos without captions, recorded talks, lectures and presentations, game playthroughs (especially ones with a lot of commentary), vlogs and travel videos, and commentary and reaction videos.

Clear speech from one person at a time gives the best results. Loud background music makes it harder.

Step by step

1. Open LiveSub and set the direction

Open LiveSub in Chrome. Under "Translate from / to", choose Japanese → English.

This step matters. Japanese uses a different recognition model, so if you leave it on English → Japanese you will get garbled text instead of subtitles.

2. Choose a recognition setting

Under "Recognition setting", Balanced is the recommended starting point for Japanese. It handles place names and people's names well.

If subtitles fall behind, choose Lighter.

If you are not sure, leave it on Balanced. You can change it later, even while subtitles are running.

3. Press "Try the how-to video (no sharing)" first

Before you use a real video, press "Try the how-to video (no sharing)". It plays a short how-to video in Japanese and shows subtitles without sharing any tab. It is a quick way to check that everything works on your computer. The first time, it waits for the recognition model to load.

4. Share the video's tab

Open the Japanese video in another tab. Back in LiveSub, press "Start (share a tab)". Chrome's sharing dialog appears:

1. Pick the "Chrome Tab" section at the top
2. Choose the tab playing the video
3. Tick "Also share tab audio" at the bottom left
4. Press Share

5. Play the video

You can press play straight away. On the first run, the model keeps downloading in the background, and subtitles start as soon as recognition is ready. After that, they appear about one to two seconds after the words are spoken.

If no sound arrives for about 12 seconds, LiveSub tells you. Check that the video is playing and not muted. If you shared the wrong tab, press "Share again".

Tips for recorded videos

Pause and rewind

The subtitles come from whatever audio is playing right now. If you pause, the subtitles pause too. If you rewind and play a part again, that part is subtitled again, so you can replay a line you missed.

Download the transcript

"Download transcript" saves the Japanese and the English with timestamps as a text file. It is useful for going back to a part later or taking notes.

Use the word list for names

Recognition often gets names wrong: people, places, game titles, in-game terms. Add the correct spellings to the "Word list", one per line (Japanese entries need at least 3 characters), and they are corrected automatically. To choose how a name appears in the translation too, write it as "たなか = Tanaka".

Watch in fullscreen

Press "Show in a floating window". The subtitles move into a small window that stays on top, so you can put the video in fullscreen and still read them.

Pick a display mode

Choose "Original and translation", "Translation only" or "Original only". If you are learning Japanese, seeing both is helpful.

Want to see the output first? Real screenshots of the English subtitles show what came out, with the delay we measured. If you are still choosing a tool, this comparison of the options sets them side by side.

Honest limits

• It is machine translation. You get the gist, but nuance, jokes and wordplay are often lost
• The Japanese text can be wrong too. Speech recognition mishears words, especially names
• About one to two seconds of delay behind the audio
• Music, sound effects and overlapping voices reduce accuracy
• Only the audio is translated. Text shown on screen is not
• Computer only. It needs Chrome or Edge on a desktop or laptop (Firefox: through a microphone or audio input)

Wrapping up

A Japanese video does not need captions for you to get English subtitles on it. LiveSub works from the audio, on any site, and you can pause and replay as usual.

Open the video you want to watch, then open LiveSub on your computer and press "Try the how-to video (no sharing)" first.

About this guide: written by the maker of LiveSub. Steps, button names and figures are checked against the LiveSub app as of the date above. If something is wrong, please tell us through the contact page.

Open LiveSub and try it