OpenAI Discontinues Fine-tuning API Effective Immediately, Existing Users Can Access Until January 6, 2027

According to OpenAI's official announcement monitored by Beating, the company is discontinuing its self-serve Fine-tuning API for developers effective immediately. New users can no longer create fine-tuning tasks, while existing active users can access the service until January 6, 2027. Deployed fine-tuned models will have their inference services tied to the lifecycle of their base models, ceasing when the base model is retired.

OpenAI stated that its new base models, such as GPT-5.5, are now sufficiently powerful in following instructions and formatting. The company said that using Prompt engineering combined with Retrieval-Augmented Generation (RAG) is cheaper, faster, and sufficient for most use cases compared to fine-tuning.