Terms of Service

Effective Date: February 16, 2026 · Last Updated: February 16, 2026

Note: For the complete, authoritative Terms of Service covering all Proso products and services, see the standalone Terms of Service. The summary below is provided for convenience; the standalone version governs in case of any discrepancy.

1. Acceptance of Terms

By installing, accessing, or using Proso (the "Extension") or any Proso service, you agree to be bound by these Terms of Service ("Terms"). If you do not agree, do not install or use Proso.

2. License

Proso is dual-licensed:

  • Open Source: Proso is available under the GNU Affero General Public License version 3.0 or later (AGPL-3.0-or-later) for personal use and open-source projects. You may use, copy, modify, and distribute Proso in accordance with the AGPL-3.0 license terms.
  • Commercial License: Businesses needing terms beyond AGPL-3.0 (proprietary integration, SaaS embedding, white-labeling) require a separate commercial license. Contact commercial@proso.com.br for details.

3. Subscription Terms

Proso offers the following subscription tiers:

Free Tier

  • Price: $0 (free forever)
  • Includes: Unlimited browser TTS, word-level highlighting, BYOK support, smart text extraction
  • No account creation required

Basic Tier

  • Price: $4.99/month or $39.99/year
  • Includes: Everything in Free, plus 100,000 managed characters per month with OpenAI voices included

Pro Tier

  • Price: $14.99/month or $119.99/year
  • Includes: Everything in Basic, plus 300,000 managed characters per month, MP3 export, cloud sync, PDF reading, credit rollover (up to 100,000 characters)

Multilingual Tier

  • Price: $19.99/month or $159.99/year
  • Includes: Everything in Pro, plus Google Cloud Text-to-Speech voices supporting 40+ languages

Billing

Paid subscriptions are billed either monthly or annually at the rates listed above. Annual subscriptions are billed as a single payment at the start of the billing period. Subscriptions auto-renew unless cancelled before the end of the current billing period.

4. Credit Policy

  • Allocation: Managed credits are allocated at the start of each billing cycle based on your subscription tier.
  • No mid-cycle expiration: Credits never expire during an active billing cycle. Your full allocation remains available until the cycle ends or renews.
  • Rollover: Pro and Multilingual tier subscribers may roll over up to 100,000 unused characters to the following billing period. Basic tier credits do not roll over.
  • Fallback: When managed credits are exhausted, the extension falls back to browser built-in TTS (always unlimited) or BYOK if configured.
  • No resale: Credits may not be transferred, sold, or exchanged.

5. Refund Policy

  • Annual plans: Full refund within 7 days of purchase, no questions asked.
  • Monthly plans: Prorated refund for the unused portion of the current billing period.
  • Free trial: Paid tiers include a 7-day free trial. You will not be charged if you cancel before the trial ends.
  • Credit usage: Refunds are calculated based on the subscription fee, not on credit usage during the period.

To request a refund, contact commercial@proso.com.br with your account email and reason for cancellation.

6. Usage Restrictions

You may NOT:

  • Reverse engineer, decompile, or disassemble the Extension beyond what is expressly permitted by applicable law or the AGPL-3.0 license
  • Remove, alter, or obscure any copyright, trademark, or proprietary notices
  • Use Proso for any unlawful purpose or in violation of applicable laws
  • Redistribute modified versions without complying with AGPL-3.0 requirements, including providing access to source code
  • Use Proso to transmit malware, viruses, or harmful code
  • Attempt to gain unauthorized access to Proso systems or networks
  • Use automated scripts or bots to consume managed credits
  • Share managed credits or subscription access between multiple users (one subscription per user)

7. API Keys and Third-Party Services

Your API Keys (BYOK)

API keys for third-party TTS providers (OpenAI, ElevenLabs, Groq, Cartesia) are stored locally in your browser using browser.storage.local. Your keys are never transmitted to Proso servers. You are responsible for keeping your API keys secure and for any charges incurred from third-party services.

Third-Party Service Terms

Proso integrates with third-party TTS providers. Your use of these services is subject to their respective terms of service, privacy policies, and usage limits. Proso is not responsible for the availability, accuracy, quality, pricing, or changes to third-party services.

8. Disclaimer of Warranties

THE EXTENSION AND SERVICES ARE PROVIDED "AS IS" AND "AS AVAILABLE" WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, AND NON-INFRINGEMENT.

Proso does not warrant that the Extension will meet your specific requirements, be uninterrupted, timely, secure, or error-free, or that results will be accurate or reliable.

9. Limitation of Liability

TO THE MAXIMUM EXTENT PERMITTED BY APPLICABLE LAW, IN NO EVENT SHALL PROSO, ITS DEVELOPERS, CONTRIBUTORS, OR LICENSORS BE LIABLE FOR ANY INDIRECT, INCIDENTAL, SPECIAL, CONSEQUENTIAL, OR PUNITIVE DAMAGES, INCLUDING BUT NOT LIMITED TO LOSS OF PROFITS, REVENUE, OR DATA, BUSINESS INTERRUPTION, OR COST OF SUBSTITUTE SERVICES, ARISING OUT OF OR IN CONNECTION WITH YOUR USE OR INABILITY TO USE THE EXTENSION.

10. Indemnification

You agree to indemnify, defend, and hold harmless Proso and its developers, contributors, and licensors from and against any claims, liabilities, damages, losses, and expenses arising out of your use of the Extension, your violation of these Terms, or your violation of any third-party rights.

11. Modifications

Proso reserves the right to modify, suspend, or discontinue the Extension or any part thereof at any time. Proso may update these Terms from time to time. Changes will be reflected by updating the "Last Updated" date. Continued use after changes constitutes acceptance of the updated Terms.

12. Governing Law

These Terms shall be governed by and construed in accordance with the laws of Brazil, without regard to conflict of law provisions.

13. Severability

If any provision of these Terms is found to be unenforceable or invalid, that provision shall be limited or eliminated to the minimum extent necessary so that these Terms otherwise remain in full force and effect.

14. Contact