On July 20, 2023, OpenAI introduced the ChatGPT Custom Instructions feature for all Plus users, giving engineers consistent control over workspace behavior for every new chat session. This feature became crucial with the rollout of OpenAI’s GPT-4o model, launched on May 13, 2024, which is often used for code generation. Users can set strict parameters through the platform’s settings menu to eliminate repetitive prompting and ensure clean scripts without conversational filler. The web interface and official mobile apps contain two text boxes: the “What would you like ChatGPT to know about you?” field has a limit of 1,500 characters for specifying programming languages, target frameworks, and daily tech stack, while the “How would you like ChatGPT to respond?” field also has a 1,500-character limit for formatting rules, such as skipping pleasantries and enforcing strict type safety. ChatGPT Plus subscription pricing has remained fixed at $20 per month as of July 2026. OpenAI officially integrated Custom Instructions into mobile apps for iOS and Android on August 9, 2023. Developers can test if their settings are active by running a simple prompt for a basic script and checking if the output adheres to their predefined formatting rules and language versions.