OpenAI has expanded its ChatGPT chatbot to almost all platforms, from desktop to mobile devices. You can run this AI model on basically any device with an internet connection, which is a testament to how large the company's audience is. However, when it comes to ChatGPT app compatibility with iPhone, it only supports the latest models running iOS17 or higher. A 17-year-old developer accepted the challenge of running ChatGPT on an older iPhone 3GS, and the results were quite interesting.

This application is called "ChatGPT for LegacyiOS". It serves as a client application for the platform and is suitable for devices that do not support the official OpenAI application. However, since it is powered by the official OpenAI API, its performance is the same as the standard app.

The developer claims that the app is more than just a "proof of concept" and supports a wide range of features from the main app to the latest versions of iOS, including contextual memory and chat history. Users also have the option to upload images for visual search on aging and nearly unusable devices.

ChatGPTforLegacyiOS is a client for legacy iOS that allows you to interact with OpenAIAPI in a variety of ways. ChatGPT for Legacy iOS supports most features found in modern chatbot applications, such as detailed text conversations with context, ChatGPT’s image analysis and image generation. Your conversations are also automatically saved so you can come back to them at any time.

If you happen to have an older iPhone, just make sure it's running iOS6 or higher. This also means that the ChatGPT application can only run on iPhone 3GS and all newer models. However, since the app cannot be distributed through official channels, you cannot install it on your device from the App Store. This means, you can install ChatGPTforLegacyiOS app on iPhone 3GS after jailbreaking the device.

After installing the app on your old iPhone, you need to obtain the ChatGPT API key from the OpenAI official website. You can visit this website to learn how to install the app, and you can also find the source code for the app on GitHub.