Developed and integrated a legacy OpenAI Completions API endpoint into the huggingface/transformers repository, enabling support for freeform text prompts and both streaming and non-streaming completion modes. This work involved implementing a dedicated CompletionHandler in Python using FastAPI, with careful handling of suffix insertion and finish_reason detection to ensure compatibility with legacy OpenAI API behaviors. The new /v1/completions route was registered for seamless API access, and the transformers serve CLI was extended to facilitate smoother migrations for users. The feature broadens tooling adoption by allowing existing workflows to interact with the updated backend infrastructure without major changes.