Privacy Policy

Last updated: August 11, 2026

PolySub is a Chrome extension that adds dual subtitles and AI translation to online video, together with this website and optional account services. This policy explains what data PolySub accesses, what leaves your device, where it goes, and what we store. The short version: we process subtitle and audio content only to translate or transcribe it, tell you which third parties that content can reach, and never sell your data.

Where the extension runs

To detect a video player and its subtitles, PolySub's content scripts load on the web pages you visit and look for video and caption data. On pages without a supported video they stay idle and collect nothing. PolySub does not read or record your browsing history, and does not track which sites you visit for any purpose beyond the on-page translation you ask for.

What the extension accesses on your device

• Subtitle and caption textof the video you are watching, read from the page (or from the video's own subtitle and manifest network responses) in order to display and translate it.
• Audio of the current video, only when you turn on Live Transcribe, and only to generate captions for it.
• Video metadata such as the title, channel, and description, when a feature you enable needs it to improve a translation or transcript.
• Your settings (languages, styling, themes, tools, and saved vocabulary/glossary), stored in chrome.storage on your device and, while signed in, synced to your PolySub account.

Community translations

If you turn on community subtitle suggestions, PolySub can match the video you are watching to community-made translations. For public videos (for example on YouTube, Vimeo, or Dailymotion), that lookup sends a video identifier and a non-reversible fingerprint of the on-screen captionsto PolySub's servers to look up or contribute a matching translation. The lookup is designed so that a generic or private page URL is not sent. Community lookup stays off until you choose to enable it. If you publish a community translation, its text and your chosen display name and license are stored and shown with the original video — see the Terms and Community Guidelines.

AI translation and transcription

Subtitle text — and, for some features, the video's title or description and short audio segments — is sent to an AI or speech-to-text provider to produce a translation or transcript. This happens in one of two ways:

• PolySub managed AI.Content is sent from your browser to PolySub's servers, which forward it to an AI provider under our own agreements. In this lane we process content transiently to return the result, store usage metadata only (request category, unit counts, credit cost, timestamps) to meter credits — not the content itself — and never use your content to train models.
• Owner-only provider testing. Supplier keys and direct provider controls are restricted to the verified PolySub owner/Admin account. Free and Pro customer accounts use managed PolySub services and cannot add their own provider key.

Provider API keys

Provider API-key entry is available only to the verified PolySub owner/Admin account for supplier testing. Customer accounts do not receive this control. PolySub's managed provider credentials remain on the server. If the owner chooses to sync a supplier key, it is sent over TLS and stored with AES-256-GCM encryption, bound to that owner account; it can be restored only after that owner authenticates again. Live Transcribe sends short audio segments through PolySub's authenticated, metered server connection rather than receiving a provider credential in the extension.

Accounts

Accounts are optional for basic instant translation. If you create an account we store your email address and authentication data (via Supabase), your plan and entitlements, synced extension settings, saved vocabulary, followed translators, creator drafts, and your PolySub credit ledger. Paid checkout, when available, is handled by Omise; PolySub stores the payment identifier, amount, method, and status but never receives or stores full card numbers, card security codes, wallet passwords, or OTPs. You can delete your account from the dashboard at any time, which removes your profile data.

Analytics

The extension does not send general product or feature-use analytics.Vercel Speed Insights runs on every website page load to measure anonymous Core Web Vitals. It records the route, broad device and browser details, country, network category, and performance metrics, but uses no cookies or persistent identifier and cannot reconstruct a visitor's browsing session. If you allow optional website analytics, we additionally use PostHog and Vercel Analytics to understand page usage. Website analytics stays off until you choose to allow it. PostHog creates a persistent anonymous identifier (and a per-session identifier) so we can count visits and page actions; Vercel Analytics records anonymized page data without cookies. None of these analytics events include subtitle text, video content, audio, account credentials, or credit values.

Data sharing

We share data only with the processors that make PolySub work — Supabase (accounts and database), Vercel (hosting), Omise (billing),PostHog (analytics), and the AI and speech providersthat return translations and transcripts — each solely to provide their function. Owner/Admin supplier tests send content directly to the selected provider under that provider's terms. Managed Live Transcribe audio is processed by OpenAI when GPT Transcribe or GPT Live Transcribe is selected, or by Deepgram for the legacy Nova-3 option. We do not sell personal data and we do not share it for advertising.

Your choices

You control when translation, Live Transcribe, community matching, and AI features run. Community matching can be enabled or disabled in the extension settings. Website analytics has its own choice on this site. You can use the extension without an account for instant translation and delete your account and its data from the dashboard at any time.

Chrome data use

PolySub's use and transfer of information received from Chrome APIs follows the Chrome Web Store User Data Policy, including its Limited Use requirements.

Changes & contact

We will update this page when the policy changes and note the date above. Questions or requests (including data access or deletion): hello.polysub@outlook.com or the support page.