Crunchyroll Dual Subs by AndyNoob

Crunchyroll Dual Sub (source here)

Web extension created to fix the annoying issue of not being able to use English and English [CC] subtitles at the same time. The extension is still in development but is guaranteed to work on shows such as One Piece where there are both types of subtitles. This extension supports Croptix and Improve Crunchyroll.

How it works

When the Crunchyroll watch page is loaded, the extension intercepts and reads your profile for your preferred/selected subtitle language and type (if you don't have one set via the dropdown). The extension then retrieves the episode's subtitle data in the same manner. The alternate subtitle will then be loaded by the extension.

Additionally, the extension now adds a drop-down menu for you to select your desired secondary subtitle. The choice is saved for your selected profile to the sync-ed storage (if it is enabled).

Caveats

While the extension is able to process most types of subtitle formats (Crunchyroll doesn't use a unified type of subtitle file), the rendering system is very limited. As such, it is recommended that you choose the none-CC version as your preferred/selected subtitle in the player. That way, the extension's renderer won't struggle displaying the more complicated typesettings (and trust me, it's not pretty).

Credits

While not completely vibe-coded, this project was made with the help of GPT-5.3/5.5. This project uses frazy-parser by ApayRus to parse subtitle files.

Footnote

See Reddit posts: post1, post2, post3, post4