Vokai
Effective July 19, 2026

Terms of Use

These terms govern your use of the Vokai application, API-backed features, and public website.

1. Agreement

By installing, accessing, or using Vokai, you agree to these Terms of Use and acknowledge the Privacy Policy. If you do not agree, do not use Vokai.

"Vokai," "we," and "us" refer to DoubleStick UG (haftungsbeschränkt), Germany. "You" means the person using the service.

2. Eligibility

Vokai is intended for adults aged 18 or older. You may use Vokai only if you are legally able to agree to these terms and your use is permitted where you live. The service is not directed to children.

3. Pseudonymous account and access

Vokai creates a pseudonymous account without requiring an account name, phone number, or email address. The app receives an authentication credential and stores it in the device's SecureStore. You are responsible for maintaining control of your device and must not extract, publish, sell, transfer, or misuse the credential.

Because the account is pseudonymous, recovery may be limited if you lose both the app data and its credential. Do not send Vokai or anyone else a credential, raw account identifier, advertising identifier, or provider alias by email.

4. Using Vokai

Vokai provides vocabulary lessons, quizzes, review tools, audio, progress features, local reminders, an Android widget, and optional monetization features. Learning content and machine-generated or curated language material may contain mistakes. Vokai is a practice aid, not a certified translation, education, medical, legal, or professional service.

You agree not to:

  • break the law or infringe another person's rights through Vokai;
  • probe, disrupt, overload, bypass, reverse engineer, or gain unauthorized access to the app, API, reward verification, or provider integrations except where applicable law expressly permits;
  • automate sessions, falsify ad or offer completions, replay requests, create abusive account farms, or manipulate points, streaks, attribution, provider aliases, or anti-fraud controls;
  • distribute malware, credentials, or deceptive instructions through any Vokai support channel; or
  • misrepresent an affiliation with Vokai or use Vokai content commercially without permission.

We may limit, suspend, or terminate access when reasonably necessary to secure the service, investigate abuse, comply with law, or enforce these terms.

5. Advertising, Offers, coins, and redemption

Advertising and consent

Vokai may show rewarded, interstitial, or other ads through Google AdMob. Ad requests are subject to the Google UMP consent process where required and fail closed when consent status cannot be established. A rewarded-ad placement is optional; a reward is credited only after valid completion and may be denied or reversed for duplicate, invalid, or fraudulent activity.

Tapjoy Offers

The Tapjoy offerwall is contacted only when you explicitly open "Offers." Each offer is supplied and controlled by a third-party advertiser, may have separate eligibility and completion rules, and may be unavailable by country, device, or account. Tapjoy uses a provider-specific alias for Vokai reward matching. Disputes about an advertiser's product or eligibility may need to be handled through Tapjoy or that advertiser, although Vokai support can help identify the correct route.

Coins and gift-card redemption

Vokai awards points, shown in the app as coins, for learning activity and optional rewarded engagement. The app indicates which part of your balance is eligible for redemption; some awards (for example bonus multipliers) may be non-redeemable. Eligible coins can be redeemed inside the app for a third-party digital gift card, currently delivered by email, subject to all of the following:

  • Minimum and limits: a minimum redemption balance applies (currently USD 3.00), together with per-day and lifetime redemption limits shown in the app. Limits and supported gift-card brands may change or vary by region.
  • Verified email and age: redemption requires a verified email address for delivery and is available only to users aged 18 or older.
  • Review period: redemption requests are held for a review period (currently up to 7 days) before fulfilment, during which the request may be checked for validity and abuse.
  • Anti-fraud: requests may be declined, held, reversed, or clawed back where activity is duplicate, automated, manipulated, made from multiple coordinated accounts, or otherwise violates section 4. By default one app installation supports redemption for one account.
  • Issuer terms: the delivered gift card is a product of its issuing brand and is governed by the issuer's own terms, expiry rules, and regional restrictions. Vokai's obligation is fulfilled when the card is delivered to your verified email address.

Coins are not money. Points, coins, XP, streaks, freezes, and other in-app counters are not property, stored value, currency, cash, securities, or a promise of future payment beyond the redemption right described here. They cannot be purchased, cannot be sold or transferred to other users, and cannot be exchanged for cash. Redemption is the only way to obtain value from coins, and unredeemed coins expire with account deletion.

Vokai may adjust or remove in-app counters to correct errors, reverse invalid rewards, prevent abuse, or change the learning economy, and may modify, suspend, or discontinue the redemption feature. Coins validly redeemed before a change are honored; accrued but unredeemed coins are not a vested right where a change is required for legal, security, or anti-fraud reasons.

6. Privacy and third-party services

The Privacy Policy explains Vokai's data practices. Optional PostHog analytics and Tenjin attribution begin only after opt-in and are revocable. A Tapjoy-enabled production build must collect and apply the applicable offer privacy choice before connection and provide withdrawal or opt-out controls; otherwise Offers remains unavailable in production. Sentry crash reports, when configured, are scrubbed and do not carry the Vokai API user identity.

Vokai uses services supplied by Cloudflare, Google, Tapjoy, PostHog, Tenjin, Reloadly (gift-card issuance), and Resend (verification email). The current release also includes the Sentry library, but its crash-reporting runtime is disabled. Third-party ads, offers, app stores, websites, products, and services are governed by their own terms and privacy practices. Vokai is not the seller of an advertiser's product and does not control its availability, claims, billing, or support.

7. Ownership and license

Vokai and its software, visual identity, interface, lesson presentation, and original content are owned by or licensed to DoubleStick UG and are protected by applicable law. Subject to these terms, Vokai grants you a limited, personal, revocable, non-exclusive, non-transferable license to use the released app for non-commercial vocabulary practice.

Third-party names, marks, libraries, ads, offers, and content remain the property of their respective owners. No rights are granted except those expressly stated here or required by open-source licenses included with the software.

8. Changes, deletion, and availability

Vokai may add, change, pause, or remove content or features; correct balances; impose technical limits; or stop providing the service. We will update public disclosures before enabling a materially different data or reward feature.

You may stop using Vokai at any time and may delete the pseudonymous account through Profile or the account deletion process. Deletion does not erase limited records that must be retained for a brief unlinkable idempotency receipt, redemption and ledger records required for bookkeeping, tax, and fraud prevention, security, disputes, or legal compliance. Redeem or forfeit any remaining eligible coins before deleting; deletion forfeits unredeemed coins.

9. Disclaimers and liability

To the extent permitted by law, Vokai is provided "as is" and "as available." We do not promise uninterrupted access, perfect lesson accuracy, specific learning outcomes, continued availability of an ad or offer, or preservation of an in-app counter.

To the extent permitted by law, DoubleStick UG is not liable for indirect, incidental, special, consequential, or punitive loss arising from use of Vokai or a third-party ad, offer, or service. Nothing in these terms excludes rights, remedies, warranties, or liability that cannot lawfully be excluded or limited, including liability for intentional misconduct or gross negligence where applicable.

10. Governing law, changes, and contact

These terms are governed by the laws of the Federal Republic of Germany, without overriding mandatory consumer protections that apply where you live. Courts with jurisdiction under applicable law may hear disputes. Before starting formal proceedings, please contact us so we can try to resolve the issue.

We may update these terms as Vokai or the law changes. The effective date above will change, and material updates may be presented in the app. Continuing to use Vokai after updated terms take effect means you accept them, where permitted by law.

Operator: DoubleStick UG (haftungsbeschränkt)
Address: Urbanstr. 182, 10961 Berlin, Germany
Contact: support@doublestick.ai
Phone: +49 176 55374207
Support: https://vokai-legal.pages.dev/support/
Company details: Impressum