The most private AI chat app for iPhone

"Private" can mean different things, so it helps to ask two questions. Where does the AI model run: on your phone or on a company's servers? And what does the app send anywhere: your chats, analytics, search questions? Here are the main options, from most private to least.

1. The model runs on your phone and the app collects nothing

Here the model runs on your phone, so your messages never leave it. Apple's App Store privacy labels let you check what the developer says it collects. checked Nov 8, 2026

• PocketPal AI: free with optional in-app purchases. Its listing says "All conversations are processed locally" and that you download model files (GGUF format, for example from Hugging Face) and then chat offline. Privacy label: Data Not Collected. Requires iOS 15.1 or later. (App Store)
• Private LLM: $4.99 one-time purchase with Family Sharing. It runs open models such as Llama, Gemma, Qwen and Mistral on the device and works without internet. Privacy label: Data Not Collected. Requires iOS 17.0 or later and an A12 chip or newer. (App Store)

The trade-off is that phone-sized models are much smaller than ChatGPT-class models. They make more mistakes and know less, and they take up storage: the Private LLM listing gives its size as 1.4 GB, before you add more models.

2. On the phone, with a little telemetry

This is where Sema sits. Sema uses Apple's on-device model when Apple Intelligence is available. Apple lists iPhone 15 Pro, the iPhone 16 models and later among the supported iPhones (Apple). On other iPhones, Sema can download Gemma 3 1B once (about 590 MB) and run it on the phone. There is no Sema account, and chats and memories are not copied to a server. Two things can leave the phone, and the Sema privacy policy describes both:

• Anonymous product analytics such as "a chat was sent" or "a memory was deleted". The text of your chats and memories is never included. Sema's App Store label lists this as Usage Data, "Data Not Linked to You".
• Web search, which is off until you allow it. Then Sema removes names, contact details and "my…" phrases from your question and sends it through Sema's server to Brave Search. Your chats and memories are not sent.

If you don't need memory or web search, the apps in group 1 collect less.

3. A cloud model with strong privacy promises

These run on a company's servers, so your messages do leave your phone. In exchange, you get stronger models and features like web search and file handling. checked Nov 8, 2026

• Lumo by Proton: Proton says conversations are "stored with zero-access encryption, so no one (not even Proton) can access them", that Lumo never uses your data to train AI, and that its code is open source. The App Store listing describes a Ghost Mode where "chats are instantly deleted once you close them." Free, with Lumo Plus at $12.99/month or $119.99/year in the app. (proton.me/lumo, App Store)
• Duck.ai (DuckDuckGo): free with no account. DuckDuckGo removes metadata such as your IP address before sending prompts to the model providers, and says its agreements with those providers forbid training on your chats and require deletion "at most within 30 days, with limited exceptions for safety and legal compliance". Recent chats are saved on your device unless you turn that off. (Duck.ai privacy policy, DuckDuckGo help)

4. Mainstream cloud assistants with privacy settings

ChatGPT is the most capable of these apps for many tasks, but it keeps your history on OpenAI's servers, and its App Store label lists data linked to you, including contact info and usage data (App Store). Its Temporary Chat mode stays out of your history and isn't used to improve models, though "OpenAI may keep a copy of a temporary chat for up to 30 days for safety purposes" (OpenAI Help). checked Nov 8, 2026

Before you trust any privacy claim, check these

• Where the model runs. On-device means your words never leave the phone. Cloud means you're trusting the company's promises and encryption.
• The App Store privacy label. "Data Not Collected" is the strictest. "Data Not Linked to You" means some data is collected without your identity attached. "Data Linked to You" is the loosest. The developer fills in the label, and Apple doesn't verify it.
• Accounts. No account means there is no profile for your chats to be tied to.
• Web search. An on-device app that searches the web has to send your search question somewhere. Find out where.
• Backups. Apple says iPhone backups include "all the information and settings stored on your device that don't already sync to iCloud", which includes app data (Apple). So chats stored on your phone can also end up in your own iCloud backup.