VoiceToSub vs Trancy: Real-Time Video Translation Compared (2026)
Trancy is one of the most popular language-learning browser extensions, offering AI-generated bilingual subtitles on YouTube, Netflix, Udemy, and more. But how does it compare to VoiceToSub for someone who just wants real-time translated subtitles without a subscription or privacy trade-off?
What is Trancy?
Trancy is a feature-rich language-learning extension available for Chrome, Edge, and Firefox. Beyond subtitles, it offers popup dictionaries, grammar analysis, vocabulary bookmarking, AI shadowing, and integrations with multiple LLMs including GPT-4, DeepSeek, Claude, and Gemini. It supports YouTube, Netflix, Udemy, TED, and general web pages — making it a compelling all-in-one tool for serious language learners.
Its AI subtitle generation feature — which transcribes video audio when no captions exist — is limited to 60 videos per day on paid plans and requires a monthly subscription.
Quick Comparison
| Feature | VoiceToSub | Trancy |
|---|---|---|
| Free Tier | Unlimited (local processing) | Word lookup only; AI subtitles require paid plan |
| Pricing | Free local or OpenAI pay-per-use | Monthly subscription (~$5–10/month) |
| Local / Offline AI | Yes — runs Whisper on your Mac | No — all processing in the cloud |
| Privacy | Audio stays on your machine (local mode) | Audio sent to OpenAI / DeepSeek / Anthropic / Google servers |
| Works on Any Web Video | Yes | YouTube, Netflix, Udemy, TED — not arbitrary sites |
| Live Stream Support | Yes (any browser tab audio) | Limited |
| Translate Local Video Files | Yes — macOS desktop app, outputs MKV | No |
| Open Source | Yes | No |
| Model Choice | 5 Whisper models (tiny to large-v3) | GPT-4, DeepSeek, Claude, Gemini (cloud-only) |
| Language Learning Features | Subtitles only | Dictionary, grammar, vocab, shadowing |
Privacy: The Core Difference
Trancy routes your video audio through multiple external AI providers — OpenAI, DeepSeek, Anthropic, or Google, depending on which you configure. For most casual use that's fine, but it means every video you watch with AI subtitles is being processed on third-party cloud servers.
VoiceToSub in local mode runs OpenAI's Whisper model directly on your Mac. No audio ever leaves your machine. This is the right choice for work videos, confidential meetings, or anyone who prefers not to share their viewing habits with AI cloud providers.
Pricing: Subscription vs. Pay-Per-Use
Trancy's free tier excludes AI subtitle generation — the core feature for watching foreign videos. A subscription is required for meaningful use, typically $5–10/month depending on plan and region. That adds up to $60–120/year.
VoiceToSub is free with local processing. For cloud quality, you use your own OpenAI API key and pay at OpenAI's current rate — pennies per hour with no subscription, no markup, and no ceiling.
Where Trancy Wins
Trancy is genuinely excellent for language learning. If your goal is to actively study a language — building vocabulary, analysing grammar, practising pronunciation with AI shadowing — Trancy's integrated toolset is hard to beat. It is purpose-built for that workflow.
Its support for multiple LLM backends also gives more flexibility in translation style if you already subscribe to those services.
Where VoiceToSub Wins
- No subscription — fully free with local AI, or pay-per-use with OpenAI
- True offline mode — works without internet once the model is downloaded
- Any web video — not limited to a whitelist of supported sites
- Local video translation — translate downloaded files from the macOS menu bar, outputs MKV with embedded subtitles
- Privacy by design — local processing means zero data leaves your machine
- Open source — verify exactly what the code does, self-host the server, contribute features
- Live streams — real-time transcription on Twitch, YouTube Live, or any tab with audio
Verdict
Choose VoiceToSub if:
- You want subtitles on any web video — not just YouTube or Netflix
- Privacy matters (local model, no cloud dependency)
- You don't want a monthly subscription
- You need to translate downloaded video files offline
- You want open-source, auditable software
Choose Trancy if:
- You are actively studying a language and want vocabulary, grammar, and shadowing tools built in
- You only watch YouTube, Netflix, and Udemy
- You prefer a polished, all-in-one language learning platform
- You already subscribe to one of the supported LLM providers
For straightforward subtitle translation on any video — especially with privacy in mind — VoiceToSub is the stronger choice. Trancy excels as a language learning suite, but that added complexity and monthly cost are unnecessary if your only goal is to understand what's being said.