Codex 5.3: Is OpenAI’s Revolutionary AI Model Actually Available to the Public?

Amid growing speculation about OpenAI’s next-generation AI model, Codex 5.3, users are questioning whether the much-anticipated upgrade is truly accessible. A recent post on the r/OpenAI subreddit from a long-time Claude user, who created their first ChatGPT account solely to evaluate the competition, revealed that the platform was still running Codex 5.2—despite widespread online rumors of a revolutionary Codex 5.3 release. The user noted that while Codex 5.3 is allegedly superior in context length and cost-efficiency, it remains conspicuously absent from public interfaces, raising concerns about transparency and rollout strategy.

Contrary to popular belief within AI enthusiast circles, there is no official OpenAI product named "Codex 5.3." The term "Codex" historically referred to OpenAI’s code-generation models, primarily Codex (powered by GPT-3), which was discontinued in 2022 in favor of GPT-4 and its derivatives. The current flagship models available via ChatGPT are GPT-4, GPT-4 Turbo, and GPT-4o, with no public release of a "Codex 5.3" version. The confusion likely stems from a misinterpretation of internal model versions or community speculation masquerading as official updates.

According to the original Reddit post, the user—identified as /u/Clean-Data-259—has been using Anthropic’s Claude since its inception and was evaluating ChatGPT for the first time. They observed that while ChatGPT’s interface appeared functional, it lacked the claimed capabilities attributed to Codex 5.3, including higher context windows and lower pricing. This aligns with broader industry observations: while GPT-4 Turbo offers a 128K token context window and competitive pricing, it does not carry the "Codex" branding. OpenAI has never used the "Codex X.X" naming convention for its general-purpose language models since retiring the original Codex API.

Experts suggest the confusion may be fueled by third-party developers or AI aggregators who mislabel GPT-4 Turbo or fine-tuned variants as "Codex 5.3" to imply superiority or exclusivity. Some AI comparison platforms and unofficial forums have perpetuated this myth, leading users to expect a non-existent model. OpenAI’s official documentation, blog, and API changelogs contain no reference to Codex 5.3, and its CEO, Sam Altman, has not mentioned such a version in any public address since 2023.

Meanwhile, Anthropic’s Claude 3 series continues to set benchmarks in long-context reasoning and cost-performance ratios, which may explain why the Reddit user felt ChatGPT remained "behind." However, OpenAI’s GPT-4o, released in May 2024, offers multimodal capabilities, faster response times, and significantly reduced latency—features not yet matched by any competing model. The absence of Codex 5.3 does not indicate stagnation, but rather a shift in branding and architecture.

For users seeking the latest OpenAI technology, the safest path is to consult official channels: chat.openai.com for consumer access, and platform.openai.com for API users. Any claims of "Codex 5.3" should be treated with skepticism until verified by OpenAI’s official communications. Until then, the model rumored to be revolutionary remains a phantom—born not of engineering, but of misinformation.