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Terms of Service

Effective date: August 14, 2026 Last updated: August 26, 2026

Welcome to KoruPDF. These Terms of Service (“Terms”) govern your access to and use of the KoruPDF Chrome extension and the byzanx.com website (collectively, the “Service”), provided by the developer of KoruPDF (“we”, “us”, or “our”).

By installing the extension or using any part of the Service, you agree to these Terms. If you do not agree, do not use the Service.

1. The Service

KoruPDF is a Chrome browser extension that allows you to:

  • Open and read PDF files entirely locally in your browser
  • Look up word definitions, pronunciation, and track vocabulary
  • Get AI-powered smart annotations and context analysis for words in your PDFs
  • Export your vocabulary to CSV or Anki formats, generate shareable word cards
  • Use reading aids: persistent highlights, reading mask, PDF overview, TTS pronunciation

Free vs. Pro

KoruPDF is free to use forever. The core reading experience — PDF rendering, dictionary lookup, TTS, vocabulary saving, highlights, reading mask, PDF overview, word card export, batch import, and basic SRS review — is permanently free with no limits.

Smart annotations and AI context analysis are limited to 5 free uses per day for free users.

KoruPDF Pro is an optional paid subscription that unlocks:

  • Unlimited smart annotations
  • Unlimited AI context analysis
  • Multi-device vocabulary sync

Pro subscription pricing and feature limits are described on the product page.

2. Eligibility

You must be at least 13 years old (or 16 in jurisdictions where that is the threshold for digital consent) to use the Service. By using the Service, you represent that you meet this requirement.

You also represent that you are not legally barred from using the Service under the laws of your jurisdiction.

3. Your License

We grant you a personal, non-exclusive, non-transferable, revocable license to install and use the extension for your own personal or professional use.

You may not:

  • Reverse engineer, decompile, or disassemble the extension, except to the extent applicable law expressly prohibits this restriction
  • Redistribute, resell, or sublicense the extension
  • Share, transfer, or sell your Pro license key to other users
  • Use the Service for any unlawful purpose
  • Attempt to disrupt or overload the Service or its backend infrastructure
  • Circumvent the daily AI quota limits or Pro subscription requirements

4. Your Content

Your PDF files never leave your browser. All PDF rendering, word detection, and vocabulary management happen locally on your device. We do not have access to your PDF files or reading history.

When you use the AI context analysis feature, only the selected word and its containing sentence are sent to our backend for processing. This data is not stored beyond transient processing.

Free users’ vocabulary data is stored only in your browser’s local storage and never leaves your device.

Pro subscribers who enable multi-device sync: your vocabulary data (saved words, mastery levels, example sentences) is uploaded to our backend (Cloudflare D1) and downloaded on your other devices to enable sync. This data is keyed to your license key. You can disable sync anytime in Settings.

You are solely responsible for the content you process with KoruPDF and for ensuring you have the rights to do so.

5. Third-Party Services

The Service integrates with:

  • Cloudflare Workers: for AI context analysis (only selected word + sentence sent) and license verification
  • Waffo Pancake (Merchant of Record): processes Pro subscription payments; our backend issues license keys automatically on subscription activation and receives subscription lifecycle events from Waffo via signed webhooks
  • CDN: for dictionary data lookups (anonymous, no user identifiers)
  • OpenRouter / LLM providers: for AI analysis features

We are not responsible for the practices of these third-party services. Your use of their services is subject to their respective terms and privacy policies.

6. Subscriptions & Payments

6.1 Subscription Plans

KoruPDF Pro is available as a monthly or annual subscription:

  • Pro Monthly: $4.99/month, with the first 30 days at $1 trial
  • Pro Annual: $39/year (equivalent to $3.25/month, save 35%)

Prices are listed in USD. Local taxes (VAT/GST) may apply and are collected by Waffo at checkout based on your billing country.

6.2 Automatic Renewal

Subscriptions auto-renew at the end of each billing cycle (monthly or annually) until you cancel. You can cancel anytime via the Waffo customer portal (link available in KoruPDF Settings → Manage subscription; Magic-Link login with your purchase email).

  • Cancellation stops future renewals but does not refund the current billing period
  • After cancellation, Pro features remain active until the end of the current billing period, then revert to Free mode

6.3 License Key & Device Limit

When you purchase Pro, our backend issues a license key automatically — Pro usually activates on its own on the purchasing device right after checkout; pasting the key in the extension (Settings → Activate Pro) is only a fallback if automatic activation fails.

  • Each license key is bound to a single device upon activation
  • A license key may be activated on up to 3 devices total
  • Attempting to activate on a 4th device will fail; you must deactivate a previous device first (email hello@byzanx.com to request device reset)
  • License keys are non-transferable between users

6.4 Trial Offers

  • 30-day trial ($1): Available for Pro Monthly subscribers. The trial period is the first 30 days; standard pricing ($4.99/month) applies after the trial ends.
  • Invite trial (14 days Pro free): When you invite a friend and they join KoruPDF, both you and your friend receive 14 days of Pro free. Limited to 3 friends (42 days max). Invite trials do not stack with paid subscriptions — if you are already a paid Pro subscriber, invite trials are not activated.

6.5 Refunds

See our Refund Policy for details. In summary: 14-day money-back guarantee on all Pro subscriptions, including the $1 trial month.

7. Disclaimers

The Service is provided “as is” and “as available” without warranties of any kind, whether express or implied. We do not guarantee that the Service will be uninterrupted, error-free, or secure.

AI-generated analysis is for informational purposes only and may be inaccurate. You should not rely on it for critical decisions.

Multi-device sync is provided on a best-effort basis. We are not responsible for data loss caused by sync conflicts, network failures, or bugs, though we will make reasonable efforts to restore your data from backups.

8. Limitation of Liability

To the maximum extent permitted by law, we shall not be liable for any indirect, incidental, special, consequential, or punitive damages arising from your use of the Service.

Our total liability for any claim arising from the Service shall not exceed the amount you paid us in the past 12 months. For free users (who have paid nothing), this amount is zero.

9. Changes to the Service and Terms

We may modify or discontinue the Service at any time. We may update these Terms from time to time; changes will be reflected in the “Last updated” date above. Continued use after changes constitutes acceptance.

If we materially change the Pro subscription terms (pricing, features, or device limits), we will notify active Pro subscribers by email (sent to the checkout email address associated with their Waffo account) at least 30 days before the change takes effect.

10. Governing Law

These Terms are governed by the laws of your jurisdiction of residence, without regard to conflict of law principles.

11. Contact

If you have questions about these Terms, please email hello@byzanx.com.

For users in the EU: under GDPR Article 27, our representative for matters relating to GDPR can be reached at the same address.