Gainsay puts several frontier models in one room, holds them to rules that stop them agreeing with each other, and tells you at the end where they actually split.
To gainsay is to speak against — to contradict. That is the whole job.
Asking four chatbots the same question gets you four essays you have to reconcile yourself. Gainsay runs one shared transcript: every model reads what the others said and has to respond to it. That is what turns four opinions into an argument, and an argument is the thing that has information in it.
Four house rules run on every reply, and they are the difference between a debate and a group nod:
When they are done, Gainsay reads the whole transcript back and gives you the part worth acting on: where they split and what each one held, where they agreed without being asked, a finding written for someone who was not in the room, and how confident it is with the reason in the same sentence.
If a disagreement matters, you can send it back to the models in it and make them defend or revise. Each one says what would prove it wrong.
Gainsay requires your own API key from Google, OpenAI, Anthropic or xAI. The app talks to those companies directly from your phone using your account, so usage is billed to you at their prices. There is no subscription to us and no markup.
One key is enough to start, and Google's free tier does not ask for a card. Any seat without its own key is filled by a model you do have, always labelled, never pretending to be someone else.
A live meter runs while the models work, counting the tokens each company reports having billed rather than a guess of our own. Documents and photos are priced before you send them, including the difference between the first turn and every turn after it. Typical conversations cost a few cents.
The meter is close, and it is not your invoice — here is where the gap is. It prices each company at one published rate, so choosing a more expensive model within that company is not reflected. A disagreement report or a challenge is billed by the AI company like anything else, but it is counted separately from the conversation’s own total. A spending limit is a threshold checked between rounds, not a hard ceiling: a round already under way always finishes, deliberately, because cutting a table off mid‑sentence is worse than overshooting — so the total can end over the line, and by more than a rounding error on a long conversation or an expensive model. And a reply you stop early may never report its final usage. The authoritative number is the one on your account with the AI company. This is the one that tells you, while you work, roughly what you are spending.
Gainsay has no backend. Your keys live in your phone’s keychain and your conversations and documents live in one file on your device. There is nothing on our side to breach, subpoena or sell, because there is no our side. What you type does go to the AI companies whose keys you add — that is how the app works, and Gainsay asks you to agree to it before it sends anything. See the privacy policy for the specifics.