Sema vs ChatGPT, Lumo, Duck.ai and local LLM apps

Who wrote this: the maker of Sema (Vilde Vevatne), so we have a stake in the result. Nobody paid to be included. Every fact about another product comes from its own website or US App Store listing, linked below, checked November 8, 2026. If we got something wrong, email vilde@vevatne.no and we'll fix it.

Scroll sideways on a phone to see every column. Prices are what each US App Store listing or website showed on November 8, 2026.

What the others do better

• ChatGPT runs far larger models than any phone can. Its listing includes image generation, Advanced Voice Mode and photo upload, and the app "syncs your history across devices". Sema does none of that. If you want the strongest answers, ChatGPT wins, and Temporary Chat keeps a conversation out of your history and out of memory. OpenAI may keep a copy "for up to 30 days for safety purposes" (App Store, OpenAI Help).
• Lumo gives you strong cloud models, web search with cited sources, image and file tools, Projects and a Ghost Mode. Proton says chats use zero-access encryption and its code is open source (App Store, proton.me/lumo). Sema's code is not open source.
• Duck.ai needs no account and no install (it works at duck.ai), lets you choose between models from several providers, and strips your IP address before prompts reach them (DuckDuckGo help, privacy policy).
• Ollama runs much bigger open models than a phone can handle, if you have a capable computer, and offers many models to choose from. Its download page lists macOS, Linux and Windows. It's a computer tool, not an iPhone app (ollama.com).
• PocketPal AI and Private LLM both list "Data Not Collected", while Sema collects anonymous usage analytics. They let you choose your own model, and they run on older iPhones: PocketPal needs iOS 15.1, and Private LLM needs an A12 chip and iOS 17. Private LLM also works with Siri and Shortcuts (PocketPal AI, Private LLM).

Where Sema is different

• Memory that stays on the phone. Sema saves lasting facts from your chats in the app's storage on your iPhone, shows the sentence each one came from, and lets you delete one or all of them.
• Apple's model first. On iPhones with Apple Intelligence, Sema uses Apple's on-device model, so there's nothing extra to download. On other iPhones, it offers a one-time Gemma 3 1B download, about 590 MB.
• No account, no server copy. We can't read your chats or memories, and we can't restore them if you delete them.
• Web search asks first. Web search stays off until you allow it. Then only a cleaned-up search question goes through our server to Brave Search. Free includes a small search allowance, and Sema Pro raises it.

Sema's limits, plainly: phone-sized models are small and can be wrong; there is no sync between devices; it is in English only; and it sends anonymous analytics (see the privacy policy).

How to choose

• You want the strongest answers and features: ChatGPT. Use Temporary Chat for sensitive questions.
• You want strong models with privacy: Lumo or Duck.ai.
• You want nothing to leave your phone, ever: PocketPal AI or Private LLM.
• You have a powerful computer: Ollama.
• You want an iPhone assistant that remembers your life, with that memory staying on the phone: Sema.