Verbalgerbil stands on open-source software. Below is what we depend on, who wrote it, and the licence it carries. Every one of them permits commercial use; two of them ask that their copyright notice travel with the software, so it does — in full, at the bottom of this page.
Shipped as part of Verbalgerbil itself.
Used to build and type-check Verbalgerbil; not shipped to your browser.
Reproduced as the licence requires, for chess.js and @daily-co/daily-js.
Copyright (c) 2025, Jeff Hlywa (jhlywa@gmail.com) — chess.js Copyright (c) 2019, daily-co — @daily-co/daily-js All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
Verbalgerbil also uses third-party services under their own commercial terms: Daily (video calls and transcription), Anthropic (the AI features), Stripe (payments, between coach and student), Neon (database), Vercel (hosting), Twilio and Resend (notifications), and Google (optional sign-in). What each one receives, and why, is set out in our Privacy Policy.