Learning and careers decision
SubLingo
A single experienced developer can reproduce the core extension + cloud sync in a few weeks using available open-source projects (e.g., VideoLingo/SmartSub) for subtitle handling and translation; paying only buys polish, scale, and the published Chrome store presence.
Visit website↗Built by Thien Nguyen, who ships 3 products in this index
$4.9/mo
$59/yr
Read off the official pricing page.
$100one-off64 h to build
$15/mo6 h/mo upkeep
On cash alone, building overtakes the subscription at 5 seats.
Open-source builds that already do this
Every project below is open source and already does this job today. Fork one, self-host it, or take the parts you need - the build prompt further down assumes an empty file, and this is the shortcut past that. Licences differ; check the one on each card before you ship. All SubLingo alternatives, with the arithmetic →
What a replacement has to do
- Detect subtitles in-page, overlay dual subtitles, provide hover translations, let user save words to a list, and provide a local/cloud-synced SRS flashcard panel for review.
What it still won’t have
- Cross-platform robustness for gated players (e.g., Netflix edge cases and future player changes)
- polished Chrome Web Store presence, reviews, and brand trust
- Payment, license handling, and LemonSqueezy checkout integration (if you want to sell)
- Ongoing moderation/abuse monitoring and large-scale analytics
What remains hard
- Product polish and ongoing maintenance
First-year cost
Keep paying
Paying is—cheaper in year one.
On cash alone, building overtakes the subscription at 5 seats.
Money you would actually spend
Time you would spend
—
What you would spend
What we assumed
The verdict above measures whether you could build it. This one is only about money.
Runnable build prompt
Build a Chrome extension + minimal Node.js (or serverless) backend. Stack: Chrome extension (manifest v3) + React for side panel UI, Node.js + Express (or serverless functions) + PostgreSQL (or Supabase) for cloud sync, and Redis or in-browser IndexedDB for caching. Core features in scope: detect and read in-page subtitles and render a synced second subtitle layer; hover-to-translate using a configurable translation/dictionary API with caching; save words from the overlay to a user word list; cloud sync and simple auth (email + token); local SRS flashcard engine with export to CSV/Anki; settings for subtitle style. Out of scope: video downloading, voice cloning/dubbing, DRM circumvention. Require: error handling for missing subtitles and failed API calls, unit tests for backend endpoints and SRS logic, end-to-end test for extension content script interacting with a test video element, and documentation for deployment and LemonSqueezy checkout integration if selling.
How we checked
How the score was reached
- Build verdict base78
- An open-source build was found+5
- 5 cited sources+3
- Price verified on pricing page+3
- Evidence score89
The base comes from the verdict. Everything under it is a check that either happened or did not, and each one is a fact frozen in this record rather than a judgement made at render time - so the same evidence always produces the same number.
How scoring works →Cited sources · 5
Every page the run actually retrieved.
- official productSubLingo — Home
- official pricingSubLingo — Pricing
- official docsSubLingo — Features
- open sourceVideoLingo (prior art)
- open sourceSmartSub (prior art)
Integrity checks
What held up, and what did not.