Terms of Use

Language Stack

Effective Date: May 12, 2026

These Terms of Use (“Terms”) govern your access to and use of the Language Stack mobile application, website, and related services collectively referred to as the “Service.”

Language Stack is operated by Brindlewood LLC, doing business publicly as Brindlewood Labs (“Brindlewood,” “we,” “us,” or “our”).

By downloading, accessing, creating an account, subscribing to, or using Language Stack, you agree to these Terms. If you do not agree, do not use the Service.

Contact information:

Brindlewood LLC
Email: support@brindlewoodlabs.com
Website: https://brindlewoodlabs.com

1. Relationship to Apple App Store Terms

If you download Language Stack through the Apple App Store, your use of the app is also subject to Apple’s applicable terms, including the Apple Media Services Terms, the Apple App Store rules, and any applicable Apple end-user license terms.

If we do not provide a separate custom end-user license agreement through App Store Connect, Apple’s Standard End User License Agreement may apply to the licensed application.

These Terms supplement the applicable Apple terms. If these Terms conflict with Apple’s required terms for App Store distribution, Apple’s terms may control to the extent required by Apple.

2. Description of the Service

Language Stack is a language-learning app that allows users to create study decks, import text, generate translations into target languages, create study cards, and practice using spaced repetition and related learning tools.

The Service is intended for personal language-learning, educational, and study purposes.

Language Stack is not a professional translation service, certified translation service, legal service, medical service, immigration service, financial service, academic editing service, or professional certification tool.

3. Eligibility

You must be at least 13 years old to use Language Stack.

By using the Service, you represent that:

You are at least 13 years old.
You have the legal capacity to agree to these Terms.
Your use of the Service complies with applicable laws.
You will provide accurate account information.

If you are between 13 and the age of majority in your jurisdiction, you should use Language Stack only with permission from a parent or guardian.

If you are using the Service on behalf of an organization, you represent that you have authority to bind that organization to these Terms.

4. Account Registration and Security

Some features require an account. You agree to provide accurate and current account information and to keep your login credentials secure.

You are responsible for all activity under your account, except to the extent caused by our negligence or a security failure within our systems.

You agree not to:

Share your account credentials with others.
Use another person’s account without permission.
Create accounts using false or misleading information.
Attempt to bypass account, subscription, usage-limit, storage-limit, or security controls.

Notify us promptly if you believe your account has been compromised.

5. User Content

“User Content” means text, words, phrases, sentences, decks, cards, imported passages, translations, notes, language selections, study materials, or other content you create, paste, upload, import, generate, store, or submit through the Service.

You retain ownership of your User Content, subject to the rights you grant us in these Terms.

By using the Service, you grant Brindlewood a non-exclusive, worldwide, royalty-free license to host, store, process, transmit, display, translate, format, and otherwise use your User Content solely as reasonably necessary to provide, maintain, secure, improve, and support the Service.

You represent and warrant that:

You have the right to use and submit your User Content.
Your User Content does not violate any law or third-party rights.
Your User Content does not contain material you are prohibited from submitting.
Your User Content does not infringe intellectual property, privacy, publicity, confidentiality, or other rights.

You are solely responsible for the User Content you submit and for any consequences of submitting it.

6. Imported Text and Third-Party Content

Language Stack allows users to import, paste, create, and store text for language-learning purposes. You are responsible for ensuring that you have the right to use any text or content you import.

You agree not to import, store, submit, or process content that:

You do not have permission to use.
Violates copyright, trademark, privacy, confidentiality, publicity, or other rights.
Contains highly sensitive personal information that you do not want processed.
Contains passwords, API keys, payment-card data, Social Security numbers, government identification numbers, protected health information, financial account details, or similar sensitive information.
Contains medical, legal, immigration, financial, proprietary, privileged, regulated, or confidential professional information that should not be sent to translation services.
Contains unlawful, abusive, exploitative, harassing, or harmful material.

Brindlewood does not claim ownership over third-party text you import, but we may process that text as needed to provide app functionality, including translation, study-card creation, storage, review, and related learning features.

Language Stack is designed for personal language-learning use. It is not designed to be a secure storage system for confidential records or a professional translation system for high-stakes documents.

7. Translation Services and DeepL

Language Stack uses DeepL to generate app translations.

When you request a translation, the text you submit may be sent from your device to Brindlewood’s backend infrastructure and then to DeepL for translation processing.

You acknowledge and agree that:

Text submitted for translation may leave your device.
Translation requests may be processed by third-party translation technology.
Translations may be inaccurate, incomplete, awkward, misleading, culturally inappropriate, grammatically incorrect, contextually wrong, or unsuitable for your intended use.
Translations are provided for personal educational, language-learning, and study purposes only.
Language Stack is not a certified, professional, legal, medical, financial, immigration, academic, emergency, or safety-critical translation service.

You agree not to rely on translations generated by the Service for medical, legal, financial, immigration, safety-critical, emergency, academic, professional, or other high-stakes decisions.

You are solely responsible for reviewing, verifying, and deciding whether any translation is appropriate for your use. For important matters, you should consult a qualified professional, certified translator, competent native speaker, or other appropriate expert.

Brindlewood does not verify, certify, or guarantee the accuracy, completeness, reliability, suitability, professional adequacy, cultural appropriateness, or educational effectiveness of any translation.

Brindlewood is not responsible for decisions, actions, losses, injuries, damages, or consequences arising from reliance on translations generated through the Service.

DeepL may process translation requests and related metadata according to its own terms, privacy policy, and data-processing practices. Our Privacy Policy explains how Language Stack handles translation content, usage records, and related metadata.

8. Machine Learning and Training

We do not use your imported text, study content, or translations to train our own machine-learning models.

Text submitted for translation may be processed by DeepL according to DeepL’s own terms, privacy policy, and data-processing practices.

9. Translation Character Limits

Language Stack may provide free and paid translation allowances.

We may track translation usage, including character counts, request timestamps, plan status, entitlement status, and account identifiers, to enforce applicable limits and prevent abuse.

The specific limits available to your account will be shown in the app and may vary by plan, subscription status, promotional access, technical constraints, product changes, or other operational reasons.

Translation limits refer to DeepL translation characters, not necessarily source-text characters.

Because Language Stack may translate one source text into two target languages, one import may use roughly twice the source text length. For example, 500 source characters translated into two target languages may use about 1,000 DeepL translation characters. If additional target languages are supported in the future, usage may increase based on the number of translations generated.

Translation limits, plan features, and usage policies may be changed, reduced, expanded, suspended, or discontinued at any time for technical, cost, business, security, fraud-prevention, abuse-prevention, or product reasons.

We may block, delay, limit, or reject translation requests that exceed applicable limits or appear abusive, automated, excessive, unlawful, or inconsistent with these Terms.

10. Text-to-Speech and Audio Features

The current DeepL translation character limit applies to text translated through DeepL.

Text-to-speech, pronunciation playback, voice, audio, speech-to-text, or other audio-related features, if added in the future, may have separate limits, pricing, restrictions, processing practices, or third-party service providers.

Unless expressly stated, translation character allowances do not include separate audio, text-to-speech, pronunciation, speech-to-text, or voice-feature usage allowances.

11. Subscriptions, Payments, Apple, and RevenueCat

Language Stack may offer paid subscriptions, free trials, promotional access, or premium features through Apple’s in-app purchase system.

If you purchase a subscription or other paid feature through the Apple App Store:

Payment will be charged to your Apple account.
Subscriptions may automatically renew unless canceled according to Apple’s rules.
You are responsible for managing, canceling, or modifying your subscription through your Apple account settings.
Refunds, cancellations, renewal issues, billing disputes, and payment-method issues are generally handled by Apple according to Apple’s policies.
Brindlewood does not directly collect or store your full payment-card number, Apple account password, or Apple billing credentials.

Language Stack uses RevenueCat to help process subscription status, validate purchases, manage entitlements, detect subscription events, and determine whether your account has access to premium features.

RevenueCat does not replace Apple as the payment processor for App Store purchases. RevenueCat helps Language Stack determine subscription status and app access.

Information processed through RevenueCat may include technical identifiers, app user IDs or anonymous identifiers, device and platform information, purchase history, product identifiers, subscription status, renewal status, trial status, cancellation status, refund status, entitlement status, timestamps, and related transaction metadata.

This information is used to provide, maintain, secure, troubleshoot, and verify access to paid features.

Premium features may include higher translation character limits, additional target-language options, enhanced study features, pronunciation or audio features, or other functionality.

Subscription features, prices, free trials, promotional offers, usage limits, plan names, and availability may change over time, subject to applicable law and Apple’s rules.

We do not guarantee that any specific premium feature, usage limit, language, translation provider, audio provider, or pricing structure will remain available permanently.

You are responsible for reviewing all subscription terms, pricing, renewal frequency, free trial terms, cancellation information, and applicable Apple disclosures before purchasing.

Deleting your Language Stack account does not necessarily cancel an active Apple subscription. To avoid future charges, you must cancel your subscription through your Apple account settings. If you delete your Language Stack account but do not cancel your Apple subscription, Apple may continue billing you according to Apple’s subscription terms.

12. Subscription Access, Entitlement Errors, and Restoration

Subscription access may depend on Apple, RevenueCat, your device, your account status, internet access, and our backend systems.

In some cases, premium access may be delayed, interrupted, incorrectly displayed, or temporarily unavailable due to network issues, Apple transaction delays, RevenueCat service issues, app bugs, device settings, account mismatch, backend outages, or other technical or platform-related issues.

Language Stack may provide a “restore purchases” or similar function where required or appropriate. Restoring purchases may require communication with Apple, RevenueCat, and/or Brindlewood’s backend systems.

We may correct subscription or entitlement errors when discovered, including granting, denying, restoring, suspending, or removing access when reasonably necessary to reflect actual subscription status, prevent fraud, comply with platform rules, or protect the Service.

13. Free Trials, Promotional Offers, and Plan Changes

We may offer free trials, promotional access, discounted pricing, or limited-time offers. These offers may be subject to additional terms, eligibility requirements, duration limits, regional availability, or platform rules.

We may modify, discontinue, or refuse promotional offers at any time, subject to applicable law and Apple’s rules.

If you change from one plan to another, your available features, pricing, renewal timing, or usage limits may change.

14. Account Deletion

If Language Stack allows account creation, users must be able to initiate account deletion in the app.

Language Stack provides or may provide an in-app account deletion flow.

Deleting your account may remove or de-identify:

Your account/authentication record.
Server-side account data associated with your account.
Server-side learning data associated with your account, where applicable.
Translation usage records associated with your account.
Local learning data stored on your device, where applicable.

Some information may be retained as required or permitted by law, including for tax, accounting, fraud-prevention, security, legal compliance, dispute-resolution, backup, transaction-record, or operational purposes.

Account deletion is different from signing out, deleting the app, resetting local content, or canceling an Apple subscription.

Deleting your Language Stack account does not necessarily cancel an active Apple subscription. To avoid future charges, you must cancel your subscription through your Apple account settings.

15. Sign Out, Reset All Content, and Delete Account

Language Stack may provide multiple account and data controls. These actions are not the same.

Sign Out

Signing out ends the current session.

In some versions of the app, signing out may remove local learning data from the device because full cloud sync may not be available.

Signing out does not delete your account and does not cancel any active Apple subscription.

Reset All Content

Reset All Content deletes local learning or study content and allows you to start over.

Reset All Content does not necessarily delete your account and does not cancel any active Apple subscription.

Delete Account

Delete Account is intended to permanently delete or de-identify your Language Stack account and associated server-side account data, subject to limited retention obligations.

Delete Account may also remove local learning data from your device, depending on the version of the app and enabled features.

You are responsible for understanding the difference between these actions before using them.

16. Local Data, Cloud Storage, and Sync Limitations

Language Stack may store some data locally on your device and some data on Brindlewood’s backend systems, including systems operated through Supabase or other service providers.

Local device data may include decks, cards, review progress, imported text, translations, app preferences, language selections, cached content, and other learning data.

Server-side data may include account information, authentication records, user identifiers, subscription-related entitlement status, translation usage records, usage limits, language settings, imported or generated study content, and other data needed to provide, secure, maintain, or improve the Service.

Full cloud sync may not be available in all versions of the Service. If full cloud sync is not available, some learning data may exist only on your device and may not be recoverable if you delete the app, reset content, sign out, delete your account, lose access to your device, switch devices, encounter a device failure, or experience an unsupported migration.

We may impose storage limits, usage limits, sync limits, account limits, deck limits, card limits, import limits, rate limits, or other technical limits to protect the Service and control costs.

We are not responsible for loss of local or cloud data caused by device loss, app deletion, reset actions, account deletion, user error, system failure, unsupported device migration, lack of cloud sync, third-party outages, or other events outside our reasonable control.

17. Acceptable Use

You agree not to use the Service to:

Violate any law or regulation.
Infringe or misappropriate intellectual property, privacy, publicity, confidentiality, or other rights.
Upload, import, process, store, or distribute unlawful, harmful, abusive, exploitative, harassing, or harmful content.
Upload, import, process, store, or distribute content that exploits, abuses, or endangers children.
Attempt to reverse engineer, scrape, crawl, copy, overload, disrupt, or interfere with the Service.
Bypass, disable, or interfere with authentication, subscription, usage-limit, storage-limit, rate-limit, or security systems.
Use automated tools, bots, scripts, bulk import methods, scraping tools, or coordinated behavior not authorized by us.
Resell, sublicense, rent, lease, share, or commercially exploit the Service without our written permission.
Use the Service to create competing products or services.
Probe, scan, or test the vulnerability of our systems.
Introduce malware, harmful code, malicious requests, or security attacks.
Use the Service for high-risk, safety-critical, legal, medical, immigration, financial, professional, or emergency translation purposes.
Use the Service to store or process excessive, automated, abusive, or unusually large volumes of content in a way that may impair the Service or create unreasonable infrastructure costs.
Attempt to exploit free-tier limits, subscription limits, translation limits, storage limits, account limits, rate limits, or promotional offers.
Use multiple accounts, scripts, bots, automated workflows, or coordinated behavior to bypass subscription requirements, translation limits, storage limits, or other restrictions.
Submit content containing passwords, API keys, payment-card data, Social Security numbers, government identification numbers, protected health information, or other highly sensitive information unless you understand and accept the risks of processing that information through third-party systems.
Use the Service in a way that creates legal, security, technical, operational, financial, or reputational risk for Brindlewood, users, service providers, or third parties.

We may suspend, limit, or terminate accounts that violate these Terms or create risk for Brindlewood, users, third-party providers, or the Service.

18. Intellectual Property

The Service, including its software, design, interface, graphics, branding, logos, workflows, features, documentation, text, visual elements, and other materials, is owned by Brindlewood or its licensors and is protected by intellectual property laws.

Subject to your compliance with these Terms, Brindlewood grants you a limited, revocable, non-exclusive, non-transferable, non-sublicensable license to access and use the Service for personal language-learning purposes.

You may not copy, modify, distribute, sell, lease, reverse engineer, create derivative works from, or exploit the Service except as expressly permitted by these Terms or applicable law.

All rights not expressly granted are reserved.

19. Feedback

If you provide feedback, suggestions, ideas, bug reports, feature requests, designs, or other comments about the Service, you grant Brindlewood a perpetual, irrevocable, worldwide, royalty-free license to use, modify, incorporate, commercialize, and otherwise exploit that feedback without restriction or compensation to you.

20. Third-Party Services and Service Providers

Language Stack relies on third-party services to operate the Service. These may include:

Supabase — authentication, database hosting, backend functions, server-side usage tracking, account records, and related storage or infrastructure.
DeepL — translation processing and related translation API services.
Apple — App Store distribution, in-app purchases, subscriptions, refunds, billing, device/platform services, and app review.
RevenueCat — subscription entitlement management, purchase validation, subscription status tracking, subscription analytics, and related transaction metadata.
Other service providers we may reasonably use for hosting, analytics, crash reporting, customer support, email, security, fraud prevention, or app operations.

Your use of Language Stack may involve third-party services. Third-party services may be subject to their own terms, privacy policies, security practices, retention practices, service availability, pricing, and technical limitations.

We are not responsible for third-party service outages, billing decisions, pricing changes, platform restrictions, app review decisions, translation errors, account restrictions, data-processing practices, or other actions outside our reasonable control.

We may add, remove, replace, or change third-party providers at any time as needed to operate, secure, improve, or modify the Service.

21. Service Availability and Changes

We may modify, suspend, discontinue, replace, limit, or remove any part of the Service at any time.

We do not guarantee that the Service will be uninterrupted, error-free, secure, available in all regions, available on all devices, or compatible with all operating system versions.

We may impose usage limits, rate limits, storage limits, feature limits, account limits, or other restrictions at any time.

We may update the app, backend, pricing, translation provider, translation limits, subscription features, supported languages, account features, or other parts of the Service at any time.

22. Beta, Test, or Pre-Release Features

We may offer beta, experimental, test, or pre-release features. Such features may be incomplete, unstable, inaccurate, unavailable, or subject to change.

We may remove or modify beta features at any time and are not responsible for loss of data or functionality associated with beta features.

If you use beta, test, or pre-release features, you understand that they may not operate correctly and may change before public release.

23. No Warranty

The Service is provided on an “as is” and “as available” basis.

To the fullest extent permitted by law, Brindlewood disclaims all warranties, express or implied, including warranties of:

Merchantability.
Fitness for a particular purpose.
Non-infringement.
Accuracy.
Availability.
Reliability.
Security.
Translation quality.
Educational outcomes.
Compatibility with your device or learning goals.

We do not warrant that the Service will meet your expectations, improve your language ability, generate accurate translations, preserve all data, remain available, remain compatible with your device, or operate without interruption or error.

Some jurisdictions do not allow certain warranty disclaimers, so some disclaimers may not apply to you.

24. Limitation of Liability

To the fullest extent permitted by law, Brindlewood and its owners, members, managers, employees, contractors, agents, affiliates, service providers, and licensors will not be liable for any indirect, incidental, special, consequential, exemplary, punitive, or enhanced damages, including loss of profits, revenue, data, goodwill, business opportunity, learning progress, device functionality, or subscription access.

To the fullest extent permitted by law, Brindlewood’s total liability for all claims arising out of or relating to the Service or these Terms will not exceed the greater of:

The amount you paid to Brindlewood for the Service in the three months before the event giving rise to the claim; or
$50.

This limitation applies regardless of the legal theory, including contract, tort, negligence, strict liability, warranty, statute, or otherwise.

Some jurisdictions do not allow certain limitations of liability, so some limitations may not apply to you.

25. Indemnification

To the fullest extent permitted by law, you agree to indemnify, defend, and hold harmless Brindlewood, its owners, members, managers, employees, contractors, agents, affiliates, service providers, and licensors from and against any claims, damages, liabilities, losses, costs, and expenses, including reasonable attorneys’ fees, arising out of or related to:

Your use or misuse of the Service.
Your User Content.
Your violation of these Terms.
Your violation of law.
Your violation of third-party rights.
Your attempt to bypass usage limits, subscription systems, storage limits, rate limits, or security controls.
Your use of translations or learning content outside the intended personal educational purpose.
Your submission or processing of confidential, sensitive, regulated, infringing, unlawful, or high-risk content through the Service.

We reserve the right to control the defense of any matter subject to indemnification, and you agree to cooperate with us.

26. Termination

You may stop using the Service at any time.

We may suspend, restrict, or terminate your access to the Service at any time if:

You violate these Terms.
Your use creates legal, security, technical, financial, operational, or reputational risk.
Your account appears fraudulent, abusive, automated, compromised, or unauthorized.
Required third-party services become unavailable.
We discontinue the Service or a material feature.
We are required to do so by law, platform rules, or service-provider requirements.

Upon termination, your right to use the Service ends immediately.

Certain sections of these Terms will survive termination, including sections relating to user content, intellectual property, feedback, third-party services, disclaimers, limitation of liability, indemnification, dispute resolution, payment obligations, and any provisions that by their nature should survive.

27. Governing Law

These Terms are governed by the laws of the State of Washington, without regard to conflict-of-law principles, except to the extent preempted by federal law or modified by mandatory consumer protection laws.

28. Dispute Resolution and Venue

Before filing a claim, you agree to first contact us at:

support@brindlewoodlabs.com

and attempt to resolve the dispute informally.

If a dispute cannot be resolved informally, any legal action or proceeding arising out of or relating to these Terms or the Service will be brought in the state or federal courts located in Washington State, unless applicable law requires otherwise.

You and Brindlewood consent to the personal jurisdiction and venue of those courts.

If you are a consumer in a jurisdiction that provides mandatory consumer rights, venue protections, or dispute-resolution rights, this section applies only to the extent permitted by law.

29. Export, Sanctions, and Legal Compliance

You agree to comply with all applicable export control, sanctions, and trade laws.

You may not use the Service if you are located in, organized under the laws of, or ordinarily resident in a country or region subject to comprehensive U.S. sanctions, or if you are on any U.S. government restricted-party list.

You may not use the Service for any prohibited end use.

30. Changes to These Terms

We may update these Terms from time to time.

If we make material changes, we may notify you through the app, website, email, or other reasonable means.

Your continued use of the Service after updated Terms become effective means you accept the updated Terms, to the extent permitted by law.

If you do not agree to updated Terms, you must stop using the Service.

31. Privacy Policy

Your use of the Service is also subject to our Privacy Policy, which explains how we collect, use, store, process, share, and protect information.

You can review the Privacy Policy at:

https://brindlewoodlabs.com/privacy-policy

32. Miscellaneous

These Terms, together with any additional terms incorporated by reference, form the entire agreement between you and Brindlewood regarding the Service.

If any provision is found unenforceable, the remaining provisions will remain in effect.

Our failure to enforce a provision is not a waiver.

You may not assign or transfer these Terms without our consent. We may assign these Terms in connection with a merger, acquisition, reorganization, sale of assets, or operation of law.

Headings are for convenience only and do not affect interpretation.

33. Contact

If you have questions about these Terms, contact: