Offline AI vs. Cloud AI
The difference is where the model runs: on their servers, or on your device.
ChatGPT runs on OpenAI's servers, so it needs a connection for every message. Offline AI runs the model on your own device, so it answers with no connection and your messages never leave it. The on-device model is smaller.
The short answer
- Choose ChatGPT for the hardest reasoning, long documents, current information, and images, files, and voice.
- Choose offline AI for conversations that stay on your device, no signal, and paying once.
- Or use both.
Head-to-head
| ChatGPT (cloud AI) | Offline AI (on-device) | |
|---|---|---|
| Where the model runs | OpenAI's servers | Your own device |
| Internet required | Yes, for every message | Once, to download the model |
| Account required | Optional on chatgpt.com in supported countries; needed to save chats | Depends on the app; often none |
| Where conversations go | To OpenAI's servers; may be used for training unless you opt out | Nowhere — they stay on the device |
| Works in airplane mode | No | Yes |
| Cost (US) | Free; Go $8, Plus $20, Pro from $100 a month | Often free or a one-time purchase |
| Model size and capability | Not published; strongest reasoning | Smaller; usually a few GB, sized to fit the device |
| Access to current information | Can search the web | None; limited to its training |
| Images, files, and voice | Extensive support | Limited; varies by app |
| Affected by provider outages | Yes | No |
Where offline AI wins
- Privacy by design. The conversation never reaches a server, so nothing has to be promised about it.
- It works where the network doesn't. See why offline AI matters.
- No monthly bill. ChatGPT Plus is $20 a month in the US; on-device apps are commonly free or sold once.
Where ChatGPT wins
- Hard problems and long inputs. The largest cloud models remain clearly ahead.
- Anything recent. It can search the web; an on-device model knows only its training.
- Images, files, voice, and tools. On-device apps are mostly text.
- More languages. The ChatGPT iPhone app lists English and 59 more. Cloak: Offline AI lists English only.
OpenAI's own offline models
The ChatGPT app has no offline mode. Separately, on August 5, 2025 OpenAI released gpt-oss-20b and gpt-oss-120b, open-weight models you can run with local AI software. OpenAI says they need 16 GB and 80 GB of memory, so they suit a computer, not a phone.
ChatGPT and Cloak on an iPhone
We make Cloak: Offline AI, so weigh this section accordingly.
| ChatGPT | Cloak: Offline AI | |
|---|---|---|
| Price (US) | Free, with Go, Plus, and Pro subscriptions | $19.99 once; no in-app purchases |
| Account | Optional on chatgpt.com in supported countries; needed to save chats | None |
| App size | 293.2 MB | 18 MB, plus a model download of a few GB |
| Works in airplane mode | No | Yes, after the model download |
| Languages | English and 59 more | English |
| App Store privacy label | Data Linked to You: Health & Fitness, Location, Contact Info, User Content, Search History, Identifiers, Usage Data, Diagnostics | Data Not Linked to You: User Content, Usage Data |
US App Store listings, checked November 3, 2026.
ChatGPT's privacy label lists eight kinds of data linked to your identity. Cloak's lists two, neither linked to you and neither a conversation: your answer to an optional one-question setup survey, and daily feature-use counts, sent only if you turn them on. See the best offline AI apps for iPhone for other on-device apps.
Common questions
Does ChatGPT work offline?
No. ChatGPT needs an internet connection for every message, because its model runs on OpenAI's servers. OpenAI's offline option is a separate product: gpt-oss, open-weight models you run on a computer with enough memory.
Do you need an account to use ChatGPT?
Not on the web in supported countries: chatgpt.com works without signing up, one unsaved conversation at a time. Saving chats and paying for a plan need an account.
Does ChatGPT use your conversations for training?
It can. OpenAI's plan comparison says content is used to train its models on the Free, Go, Plus, and Pro plans, with an opt-out: turn off “Improve the model for everyone” under Data controls in Settings.
Is offline AI as good as ChatGPT?
Not on the hardest tasks. The largest cloud models remain stronger at complex reasoning, long documents, and anything needing current information. For everyday questions and writing help, an on-device model can be enough.
Can offline AI run on an iPhone?
Yes. Several App Store apps run a language model on an iPhone and answer with no connection once the model is downloaded.
Do offline AI apps require a subscription?
Often not. With no servers running the model, many on-device apps are free or sold once. Some charge a subscription for optional cloud features.
Sources
ChatGPT's plans, prices, request limit, and training opt-out are from OpenAI's pricing page; account-free use and the Data controls setting from its help article on the ChatGPT home page; gpt-oss from its announcement; and app sizes, languages, and privacy labels from the US App Store listings for ChatGPT and Cloak: Offline AI. All checked November 3, 2026. Prices and availability differ by region.
Cloak: Offline AI
Chat, Voice Memos, and Recap. $19.99 once.
