ChatGPT’s custom GPTs, now available as of December 2025, allow Australian businesses to create tailored versions of ChatGPT for specific tasks without needing coding experience. These customisations function as dedicated AI assistants trained on your provided data and instructions, accessible through the ChatGPT interface.
Currently, creating a custom GPT involves using the ‘Create a GPT’ option within ChatGPT Plus. You define its personality, instructions, and knowledge base by uploading files (up to 20MB per file – supporting PDF, TXT, CSV formats) or linking to external websites. In 2026, OpenAI plans to increase the file upload limit to 100MB and introduce support for more complex data structures. Australian businesses can use this to train a GPT on their product catalogues, internal documentation, or brand guidelines. The GPTs are then accessible privately within your organisation or, optionally, made public on the GPT Store (launched in late 2025).
The functionality relies on ChatGPT’s underlying large language model, but the custom instructions and knowledge base significantly refine its responses. Pricing for custom GPT usage is based on the standard ChatGPT Plus subscription cost, with additional charges potentially applying for API usage if integrating with other systems. Understanding the limitations of the underlying model and carefully crafting instructions are key to achieving useful results.