OpenCat - Native iOS/macOS/iPadOS client for OpenAI/ChatGPT
Early Moon, LLC · Chatbot · Prompts
OpenCat is a native AI chat client for iPhone, iPad, and Mac, with 50+ models, MCP tools, local models, and an AI keyboard, powered by your own API key or OpenCat Cloud.
About OpenCat - Native iOS/macOS/iPadOS client for OpenAI/ChatGPT
What Is OpenCat
OpenCat is a chat app built by Early Moon, LLC for Apple devices. It connects to OpenAI, Anthropic, Google, and 25+ other providers, so you can keep several assistants in one place instead of juggling browser tabs. Many users treat it as a ChatGPT app for iOS that also happens to run on iPad and Mac.
The app solves a narrow but real problem. The official ChatGPT app locks you to OpenAI models and an OpenAI account. OpenCat lets you pick the provider, paste a key, and pay that provider directly for what you use. It also adds system-level tools the web version can't offer: an AI keyboard, Siri shortcuts, and system-wide AI translation.
The limits are worth knowing up front. Setup takes more steps than signing into a website, and most of the system integrations sit behind the Pro unlock. Model quality is whatever your provider delivers, since OpenCat is the client, not the model.
Getting Started
- Download OpenCat from the App Store on your iPhone, iPad, or Mac.
- Pick a path: subscribe to OpenCat Cloud for instant access, or open Settings and paste an API key from a provider.
- Choose a model for the chat, then set a system prompt or load a saved prompt from the prompt library.
- Chat, or enable the AI keyboard and Siri shortcuts to reach the same models from other apps.
Product Information
A quick look at OpenCat - Native iOS/macOS/iPadOS client for OpenAI/ChatGPT's pricing, supported platforms, and performance.
Best for
The users, tasks, and scenarios where this tool fits best.
Users
- ChatGPT power users who already hold an OpenAI key
- Apple users who want AI in every app
- Privacy-minded users and frequent flyers
Tasks
- Polishing an email or a message inside another app
- Translating a paragraph you selected in Safari or Mail
- Running multi-step jobs with outside tools
- Comparing answers from several models
Scenarios
- Writing on a Mac all day
- Quick questions on a phone
- Working on a plane or in a dead zone
Key features
Native Apps for iPhone, iPad, and Mac
OpenCat is written as a native Apple app rather than a wrapped website. Scrolling stays smooth with long threads, the interface follows system dark mode, and the iPad layout uses the extra screen space for a sidebar. That polish matters once you spend hours in a chat window.
OpenCat Cloud with 50+ Models
The Cloud subscription removes setup entirely. You get ChatGPT, Claude, Gemini, Grok, DeepSeek, GLM, Kimi, Qwen, Doubao, and other models in one list, with web search available on supported models. Billing runs at OpenAI API cost with no markup, minus the Apple tax on the subscription itself.
Bring Your Own API Key
If you already pay a provider, connect it through bring your own API key support and skip the middleman. OpenCat accepts 25+ providers, including OpenAI, Anthropic, Google, DeepSeek, Kimi, Qwen, Doubao, and ERNIE. You can also point it at a compatible endpoint, which covers most self-hosted gateways.
MCP Support and Tool Calls
MCP support turns the chat into an agent. Connect an MCP server and the model can call tools, read files, or fetch data mid-conversation instead of guessing. This is the feature that separates OpenCat from a plain chat window, and it works with both Cloud models and your own keys.
AI Keyboard and System Translation
The AI keyboard sits in the text field of any app, so you can rewrite a sentence in Messages or draft a reply in Mail without copying text back and forth. Set OpenCat as the default translation app and selected text in Safari, Mail, or Notes gets translated in place. Both features need the Pro unlock.
Prompt Library and Rich Rendering
The prompt library stores reusable instructions and syncs them across devices, which saves retyping the same setup every morning. Chats render Markdown, LaTeX formulas, and highlighted code blocks, so technical answers stay readable without a second app.
Local Models with Offline Inference
OpenCat downloads open models such as Llama, Qwen, and Gemma and runs them through Apple's MLX framework. Apple silicon handles the compute, so replies arrive quickly without a network call. Download a model once and it keeps working on a flight or in a basement with no signal.
iCloud Sync, Siri, and Shortcuts
Chats live on the device and sync through iCloud, so a thread started on the iPhone continues on the Mac. Siri integration and Shortcuts open a new chat or run a saved prompt by voice. No account signup is needed for the core app, which keeps the setup short.
Pros and cons
Pros
- Native performance on Apple hardware, with iCloud sync that keeps threads aligned across iPhone, iPad, and Mac.
- Real model choice: Cloud, your own API keys, or offline local models, all inside one interface.
- System-level reach through the AI keyboard, default translation app, Siri, and Shortcuts.
- MCP support and tool calls give the assistant access to files and services, not just conversation history.
- Pro is a one-time purchase, so the extra features don't add a recurring bill.
Cons
- Setup asks more of you than a normal chat app: a provider account, a key, and billing details before the first reply.
- Key features such as the AI keyboard, Siri integration, and text to speech require the Pro unlock, so the free tier feels like a trial.
- Cloud usage is capped by the subscription price after the Apple fee, which means heavy users hit the monthly limit and need an API key anyway.
- No Android or Windows version exists, so anyone on a phone or PC outside Apple's lineup can't use it at all.
Frequently asked questions
Yes. The app downloads for free and the basic chat, prompt library, Markdown rendering, and multiple model support work without payment. Pro features and the Cloud subscription cost extra.
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