OpenAI Introduces GPT-5.3-Codex-Spark
In a post, OpenAI announced and detailed its latest coding model. The GPT-5.3-Codex-Spark is currently available in research preview to ChatGPT Pro subscribers across the Codex app, command line interface (CLI), and integrated development environment (IDE) extension. Since the full version has not been rolled out, those using the model will experience certain limitations for the time being.
Apart from its unusually long name, Codex-Spark’s standout capability is real-time coding. The company said the model is designed for low-latency workloads and can write and edit code almost instantly. The model is said to process 1,000 tokens per second.
It is a text-only model that writes code, makes targeted edits, reshapes logic, and refines interfaces in real-time. It comes with a context window of 1,28,000 tokens, making it fairly capable of handling regular to mildly challenging tasks. However, for more complex tasks, users should stick to the GPT-5.3-Codex model.
Apart from code-level optimisations, what makes Codex-Spark fast is that the AI model runs on low-latency hardware. OpenAI announced a partnership with Cerebras last month, and as part of it, the new model now runs on its Wafer Scale Engine 3 AI accelerator that offers high-speed inference.
Coming to performance, the AI giant shared internal benchmark evaluations to claim that on SWE-Bench Pro and Terminal-Bench 2.0, which measures agentic software engineering capability, the Codex-Spark outperforms GPT-5.1-Codex-mini and slightly falls short of GPT-5.3-Codex. However, with the faster output generation, this is a big leap.
OpenAI said the AI model will also be available to a small set of design partners via the application programming interface (API) to help the company understand how developers intend to integrate it in their products. Notably, Codex-Spark will have its own rate limits, and usage will not count towards standard rate limits. The company said expansion will be expanded over the coming weeks.
