Marfondo Subtitles by Marfondo
Interactive language-learning subtitles on YouTube, Netflix, Crunchyroll, and any video site — synced with your Marfondo account.
Available on Firefox for Android™Available on Firefox for Android™
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About this extension
Learn a language from the shows and videos you already watch.
Marfondo Subtitles adds interactive subtitles to YouTube, Netflix, Crunchyroll, and other video sites. Click any word to see its meaning, mark words as known or unknown, and save them to your Marfondo vocabulary — all without leaving the video.
• Clickable subtitles: tap any word for a definition and translation
• Two lines at once: your study language, with a translation in your native language underneath
• Full transcript panel: every line of the video, click to jump to it
• Keyboard shortcuts: step line by line (A / D), mark words with 1, 3, 4
• Drag the subtitles anywhere on the player; your position is remembered
• Tracks your study time, and only counts videos recorded in your study language
• Works on YouTube, Netflix, and Crunchyroll out of the box; turn it on for other video sites with one click
• Everything syncs with your Marfondo account and the Marfondo web app
Requires a Marfondo account (marfondo.com). [Free / Pro line — see below]
Marfondo is not affiliated with YouTube, Netflix, Crunchyroll, or any other video service.
Marfondo Subtitles adds interactive subtitles to YouTube, Netflix, Crunchyroll, and other video sites. Click any word to see its meaning, mark words as known or unknown, and save them to your Marfondo vocabulary — all without leaving the video.
• Clickable subtitles: tap any word for a definition and translation
• Two lines at once: your study language, with a translation in your native language underneath
• Full transcript panel: every line of the video, click to jump to it
• Keyboard shortcuts: step line by line (A / D), mark words with 1, 3, 4
• Drag the subtitles anywhere on the player; your position is remembered
• Tracks your study time, and only counts videos recorded in your study language
• Works on YouTube, Netflix, and Crunchyroll out of the box; turn it on for other video sites with one click
• Everything syncs with your Marfondo account and the Marfondo web app
Requires a Marfondo account (marfondo.com). [Free / Pro line — see below]
Marfondo is not affiliated with YouTube, Netflix, Crunchyroll, or any other video service.
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Permissions and data
Required permissions:
- Access your data for sites in the netflix.com domain
- Access your data for sites in the youtube.com domain
- Access your data for marfondo.com
Optional permissions:
- Access your data for sites in the youtube.com domain
- Access your data for sites in the netflix.com domain
- Access your data for sites in the nflxvideo.net domain
- Access your data for sites in the nflxso.net domain
- Access your data for marfondo.com
Required data collection, according to the developer:
- Browsing activity
- Website activity
- Website content
More information
- Add-on Links
- Version
- 0.2.4
- Size
- 107.87 KB
- Last updated
- 6 hours ago (Nov 2, 2026)
- Related Categories
- License
- All Rights Reserved
- Version History
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