Everyone who uses ChatGPT and Claude knows the dance: ask one, copy the answer, paste it into the other, ask "is this right?". Poly Duo (C1M) does that dance for you on iPhone, in one tap.
ChatGPT answers. Claude checks it and fixes what's wrong. You get one answer that opens with three short blocks (where both agree, where they differ, what to check yourself), on screen, in the clipboard and in a journal file in iCloud Drive, in about a minute.
- Runs on the ChatGPT and Claude apps you already have, through their official Ask ChatGPT and Ask Claude actions: no server, no API keys, no gateway
- Free accounts are enough; with Plus or Pro, the strongest models of two companies work together at no extra cost
- 12 modes in one shortcut: Critique, Debate until agreement, Dispute map, Synthesis, Side by side, Decision, Advisor, Clarify, Delta, Image, Auto and more
- Put it on the Action Button, Back Tap or Siri and it becomes a "second opinion" button
- 11 languages; any iPhone on iOS 18 or later
This has existed on computers as browser extensions, paid AI hubs and API setups. On a phone, free, with nothing in between, there was nothing like it until now.
Built by the author of two papers on AI verification accepted at NeurIPS 2026 workshops. In our data on the 5 August 2026 flagships (a re-analysis of our companion study's data), when ChatGPT (gpt-5.6-sol) and Claude (claude-fable-5) answered 1,459 factual questions independently and agreed, they were right 98% of the time (985 of 1,004).
Free and open source (Apache-2.0). On Android the same pair lives inside the free Poly A1 app.
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