OpenAI is strengthening its push into AI-powered coding tools with the release of a new model designed for real-time development tasks.
The San Francisco-based AI company has introduced GPT-5.3-Codex-Spark, its first model capable of writing and editing code in real time. The launch follows the recent debut of GPT-5.3-Codex earlier this month, marking a shift where OpenAI prioritised a coding-focused model over a general-purpose version. Last week, CEO Sam Altman reportedly described Codex’s growth as “insane” after it expanded by 50% in a single week.
GPT-5.3-Codex-Spark is currently available in research preview for ChatGPT Pro subscribers. It can be accessed through the Codex app, command line interface (CLI), and integrated development environment (IDE) extension. Since it is not fully rolled out, users may face certain limitations.
The model’s key feature is low-latency, real-time coding. OpenAI said it is built for fast workloads and can write and modify code almost instantly. It processes up to 1,000 tokens per second.
Codex-Spark is a text-only model. It can generate code, make targeted edits, adjust logic, and refine interfaces in real time. It supports a context window of 1,28,000 tokens, making it suitable for regular and moderately complex tasks. For more advanced coding challenges, OpenAI recommends using GPT-5.3-Codex.
A major factor behind its speed is specialised hardware. OpenAI recently partnered with Cerebras, and the new model runs on the Wafer Scale Engine 3 AI accelerator, which enables high-speed inference.
In internal benchmark tests, OpenAI said Codex-Spark outperformed GPT-5.1-Codex-mini on SWE-Bench Pro and Terminal-Bench 2.0, both of which evaluate agentic software engineering capabilities. However, it slightly trails GPT-5.3-Codex in overall performance. Despite this, the faster output generation marks a significant improvement.
The model will also be made available to a limited group of design partners via API. OpenAI said Codex-Spark will have separate rate limits, and its usage will not count toward standard limits. Wider expansion is expected in the coming weeks.
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