9 best AI apps for iPhone Duo in 2026
The 9 best AI apps for iPhone Duo: chat assistants, research tools, transcription and on-device writing, and how they compare with Siri AI.
The iPhone Duo already ships with Apple Intelligence and Siri AI, so the first question is whether you need another AI app at all. For many people the answer is yes: third-party assistants are better at long conversations, research and coding. Here are the 9 worth trying, and what each one is best at. For the built-in features, read what Siri AI can do on iPhone Duo.
How well a third-party app uses the Duo's 7.6-inch inner display depends on whether its developer has updated the layout for the fold. Apps that are not updated can show black bars in Split View. For the screen sizes involved, see our screen size guide.
1. ChatGPT: best for an all-round assistant
OpenAI's app handles writing, questions, photo analysis and natural voice conversations. The free tier has usage limits, and paid plans raise them. On the inner display, long answers are much easier to read.
2. Claude: best for long documents and careful writing
Anthropic's Claude is good at reading long PDFs and producing clear, structured writing. It has a free tier and a Pro subscription.
3. Gemini: best for Google users
Google's Gemini works with Gmail, Docs and Maps if you use Google services. The free version covers most tasks, and a paid Google AI plan adds the more capable models.
4. PromptSlate Studio: best for AI scripts you can read on camera
Our app. Most AI apps stop at the text. PromptSlate Studio uses Apple's on-device Foundation Models to draft and tighten a script, then puts that script straight into the teleprompter next to the camera, so there is no copy and paste. Your scripts are not sent to a server. We explain how Creator Assist works in part 7 of our build log. It is in final development for iOS 27.1 and will be a $9.99 one-time purchase, with no subscription.
See PromptSlate Studio for iPhone Duo
5. Perplexity: best for research with sources
Perplexity answers questions with cited web sources, so you can check where each claim comes from. A free tier is available, with a Pro subscription.
6. Microsoft Copilot: best for a free alternative
Copilot offers chat, image generation and voice for free with a Microsoft account. It is a good pick if you already use Microsoft 365.
7. Otter.ai: best for meeting transcripts
Otter records and transcribes meetings and lectures and writes a summary. The free tier has a monthly limit on minutes. For recording quality, see our audio recording guide.
8. Grammarly: best for fixing your writing everywhere
Grammarly adds a keyboard that checks grammar and tone in any app. The free version covers corrections, and Premium adds rewrites.
9. Apple Intelligence: best for privacy and system-wide tools
Built in, not an app you download: Writing Tools, notification summaries, Clean Up in Photos and Image Playground run across the system, much of it on device. See Apple Intelligence photo editing.
The bottom line
Pick one general assistant (ChatGPT, Claude or Gemini), add Perplexity if you research a lot, and lean on Apple Intelligence for the system-wide tools. If you make videos, our script writing list covers the next step.
More iPhone Duo app guides
From the maker
Get PromptSlate Studio on the App Store
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See PromptSlate Studio details · Also in the works: DuoSketch
Spotted something to fix, or an app we should cover?
This article is independent research, cross-checked against Apple's developer documentation. If something's out of date, or you know an app that deserves a look, let us know — and if you're building for iPhone Duo yourself, we're happy to talk.
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