Tidyleaf

YouTube with Japanese and English subtitles at the same time

YouTube’s player shows one subtitle track at a time, so you cannot turn on Japanese and English together from the CC menu. To see both lines at once you need a browser extension (such as Language Reactor or our Tidyleaf Dual Subtitles) that draws a second line over the video, or a learner site that shows the two tracks beside the player. All of them need the video to have Japanese captions to begin with, and extensions do not run in the YouTube phone apps.

What YouTube can do on its own

One track at a time: the gear icon, then Subtitles/CC, then Japanese or English.
Auto-translate: in the same menu, choose Auto-translate and a language. This replaces the Japanese line with a machine translation; it does not add a second line.
Show transcript: under the video description. It lists every line with its timestamp, but in the one language you picked, beside the video rather than on it.

A workable free trick without installing anything: watch with Japanese captions on the video, and when you get lost, pause and switch the track to English (or to Auto-translate, English) for that line. It works, but switching back and forth breaks the flow, which is why most learners end up with a tool that shows both lines.

Check the video first: which subtitle tracks does it have?

Open the gear, then Subtitles/CC, and look at the list:

“Japanese” is a human-made track. This is what you want to study from.
“Japanese (auto-generated)” is YouTube’s speech recognition. It is usable, but it gets names, slang and fast speech wrong, and it usually has no punctuation, so lines run together.
“English” without “auto-generated” is a human translation. When a video has both a human Japanese and a human English track, any two-line tool will give you the best possible result.

Channels made for learners, news and NHK-style programs, and talks are more likely to have human-made Japanese captions than vlogs or games streams.

Your options

Language Reactor (Chrome extension)

Language Reactor is the best-known tool for this. It shows two subtitle lines on YouTube and Netflix, with a free tier and a paid plan, and it is widely used by Japanese learners. If you also watch Japanese shows on Netflix, one tool covering both sites is a real advantage. Check its current feature list and pricing on its own site before relying on a particular feature, as they change.

CaptionPop (website)

CaptionPop is a site rather than an extension: you pick your language and the one you are learning, and it finds YouTube videos that already have both subtitle tracks, then shows the two side by side. It is useful for finding videos with human-made Japanese and English captions, but it only covers videos that have both tracks.

Tidyleaf Dual Subtitles for YouTube (Chrome extension)

Disclosure: Tidyleaf is us, and this is our product.

Japanese is supported both as the video’s language and as a translation target, so it covers this case. What it does, free:

Two lines over the player on regular videos and Shorts: the video’s own captions on top and a translation underneath.
The original line is the video’s spoken language, human-made captions first, falling back to auto-generated ones. On a Japanese video that is the Japanese track.
The second line comes from the best source available, in this order: a creator’s own English track if the video has one, then YouTube’s built-in translation, and only then a free machine-translation service.
Stays in sync when you seek, slow the video down, skip ads or move to the next video.
Font size, top or bottom position, and hiding the original line are in the toolbar popup.

Two settings to change for Japanese:

Check the target language. Until you pick one, it translates into your Chrome display language, so with Chrome in English a Japanese video gets English underneath. If Chrome is set to Japanese or a language the extension does not offer, a Japanese video is translated into Traditional Chinese instead; pick English once in the popup.
Leave Pronunciation off. The pinyin and zhuyin option is for Chinese. A Japanese line that is mostly kanji can be annotated with Chinese readings, which are wrong for Japanese.

What it does not do for Japanese, so you can judge it fairly: there is no furigana and no romaji, and no dictionary pop-up. If you need readings above kanji, ours is not the right tool for that.

The reverse direction works too: on an English video, set the target to Japanese and you get English on top and Japanese underneath.

Tidyleaf Pro ($24 a year or $3.99 a month) adds SRT download of the subtitles (both lines, original only, or translation only), click a word to save it with its sentence and timestamp, and a saved-words page with CSV export for Anki. Word picking splits Japanese text into words even though it has no spaces. Get Tidyleaf Pro. Everything in the free list stays free.

Add to Chrome, free Tidyleaf Dual Subtitles for YouTube is on the Chrome Web Store.

Which one to use

You want	Use
No install, occasional use	YouTube’s CC menu, switching tracks when you get lost
Videos that already have human Japanese and English captions	CaptionPop to find them, or any two-line extension
Japanese on YouTube and Netflix with one tool	Language Reactor
Furigana or readings above kanji	A tool that advertises furigana; not ours
YouTube only, two lines free, SRT export for study	Tidyleaf Dual Subtitles

Limits every option shares

No Japanese captions, no Japanese line. If the video has no Japanese track at all (not even auto-generated), no extension can show one. Music videos and silent clips often have none.
Auto-generated Japanese is the weak link. A wrong recognised line is translated wrongly too. Prefer videos with a human-made Japanese track for study.
Machine translation from Japanese is loose. Japanese drops subjects and relies on context, so a line-by-line translation often guesses who is speaking or doing what. A creator’s human English track is far better when it exists.
Extensions need a desktop browser. The YouTube apps on iOS and Android do not run browser extensions.

FAQ

Can YouTube show two subtitles at once without an extension? No. The player shows one track. Auto-translate replaces the original line rather than adding a second one.

Is there a free extension for Japanese and English subtitles on YouTube? Yes. Language Reactor has a free tier, and Tidyleaf Dual Subtitles shows both lines free with no time limit.

Can I get furigana on YouTube Japanese subtitles? Not from YouTube itself. Some learner extensions add readings above kanji; Tidyleaf Dual Subtitles does not.

Why is the English line a machine translation when the video has English subtitles? Usually because the “English” track you saw is YouTube’s auto-translate, not a creator’s track. A human English track appears in the CC list as plain “English”. Ours uses a human track first when there is one.

Can I do the same on Netflix? Netflix also shows one track at a time, and the same kind of extension fixes it. See Netflix dual subtitles. For Chinese and English on YouTube, see YouTube with Chinese and English subtitles at the same time.

Tidyleaf is an independent maker of browser extensions. Not affiliated with, endorsed by or sponsored by YouTube, Google, Language Reactor or CaptionPop. “YouTube” is a trademark of Google LLC, used only to describe the site the extension works on.