OpenAI has launched GPT‑5.1-Codex-Max, a brand new frontier agentic coding mannequin now accessible in its Codex developer setting. The discharge marks a big step ahead in AI-assisted software program engineering, providing improved long-horizon reasoning, effectivity, and real-time interactive capabilities. GPT‑5.1-Codex-Max will now change GPT‑5.1-Codex because the default mannequin throughout Codex-integrated surfaces.
The brand new mannequin is designed to function a persistent, high-context software program improvement agent, able to managing complicated refactors, debugging workflows, and project-scale duties throughout a number of context home windows.
It comes on the heels of Google releasing its highly effective new Gemini 3 Professional mannequin yesterday, but nonetheless outperforms or matches it on key coding benchmarks:
On SWE-Bench Verified, GPT‑5.1-Codex-Max achieved 77.9% accuracy at extra-high reasoning effort, edging previous Gemini 3 Professional’s 76.2%.
It additionally led on Terminal-Bench 2.0, with 58.1% accuracy versus Gemini’s 54.2%, and matched Gemini’s rating of two,439 on LiveCodeBench Professional, a aggressive coding Elo benchmark.
When measured in opposition to Gemini 3 Professional’s most superior configuration — its Deep Pondering mannequin — Codex-Max holds a slight edge in agentic coding benchmarks, as effectively.
Efficiency Benchmarks: Incremental Features Throughout Key Duties
GPT‑5.1-Codex-Max demonstrates measurable enhancements over GPT‑5.1-Codex throughout a spread of normal software program engineering benchmarks.
On SWE-Lancer IC SWE, it achieved 79.9% accuracy, a big enhance from GPT‑5.1-Codex’s 66.3%. In SWE-Bench Verified (n=500), it reached 77.9% accuracy at extra-high reasoning effort, outperforming GPT‑5.1-Codex’s 73.7%.
Efficiency on Terminal Bench 2.0 (n=89) confirmed extra modest enhancements, with GPT‑5.1-Codex-Max reaching 58.1% accuracy in comparison with 52.8% for GPT‑5.1-Codex.
All evaluations have been run with compaction and extra-high reasoning effort enabled.
These outcomes point out that the brand new mannequin provides the next ceiling on each benchmarked correctness and real-world usability beneath prolonged reasoning masses.
Technical Structure: Lengthy-Horizon Reasoning through Compaction
A significant architectural enchancment in GPT‑5.1-Codex-Max is its capability to cause successfully over prolonged input-output periods utilizing a mechanism known as compaction.
This allows the mannequin to retain key contextual info whereas discarding irrelevant particulars because it nears its context window restrict — successfully permitting for steady work throughout thousands and thousands of tokens with out efficiency degradation.
The mannequin has been internally noticed to finish duties lasting greater than 24 hours, together with multi-step refactors, test-driven iteration, and autonomous debugging.
Compaction additionally improves token effectivity. At medium reasoning effort, GPT‑5.1-Codex-Max used roughly 30% fewer considering tokens than GPT‑5.1-Codex for comparable or higher accuracy, which has implications for each price and latency.
Platform Integration and Use Instances
GPT‑5.1-Codex-Max is at present accessible throughout a number of Codex-based environments, which consult with OpenAI’s personal built-in instruments and interfaces constructed particularly for code-focused AI brokers. These embrace:
Codex CLI, OpenAI’s official command-line device (@openai/codex), the place GPT‑5.1-Codex-Max is already stay.
IDE extensions, probably developed or maintained by OpenAI, although no particular third-party IDE integrations have been named.
Interactive coding environments, similar to these used to reveal frontend simulation apps like CartPole or Snell’s Regulation Explorer.
Inside code evaluate tooling, utilized by OpenAI’s engineering groups.
For now, GPT‑5.1-Codex-Max just isn’t but accessible through public API, although OpenAI states that is coming quickly. Customers who want to work with the mannequin in terminal environments right now can accomplish that by putting in and utilizing the Codex CLI.
It isn’t at present confirmed whether or not or how the mannequin will combine into third-party IDEs until they’re constructed on prime of the CLI or future API.
The mannequin is able to interacting with stay instruments and simulations. Examples proven within the launch embrace:
An interactive CartPole coverage gradient simulator, which visualizes reinforcement studying coaching and activations.
A Snell’s Regulation optics explorer, supporting dynamic ray tracing throughout refractive indices.
These interfaces exemplify the mannequin’s capability to cause in actual time whereas sustaining an interactive improvement session — successfully bridging computation, visualization, and implementation inside a single loop.
Cybersecurity and Security Constraints
Whereas GPT‑5.1-Codex-Max doesn’t meet OpenAI’s “High” functionality threshold for cybersecurity beneath its Preparedness Framework, it’s at present probably the most succesful cybersecurity mannequin OpenAI has deployed. It helps use circumstances similar to automated vulnerability detection and remediation, however with strict sandboxing and disabled community entry by default.
OpenAI reviews no enhance in scaled malicious use however has launched enhanced monitoring methods, together with exercise routing and disruption mechanisms for suspicious conduct. Codex stays remoted to an area workspace until builders opt-in to broader entry, mitigating dangers like immediate injection from untrusted content material.
Deployment Context and Developer Utilization
GPT‑5.1-Codex-Max is at present accessible to customers on ChatGPT Plus, Professional, Enterprise, Edu, and Enterprise plans. It’ll additionally develop into the brand new default in Codex-based environments, changing GPT‑5.1-Codex, which was a extra general-purpose mannequin.
OpenAI states that 95% of its inside engineers use Codex weekly, and since adoption, these engineers have shipped ~70% extra pull requests on common — highlighting the device’s influence on inside improvement velocity.
Regardless of its autonomy and persistence, OpenAI stresses that Codex-Max must be handled as a coding assistant, not a alternative for human evaluate. The mannequin produces terminal logs, take a look at citations, and power name outputs to assist transparency in generated code.
Outlook
GPT‑5.1-Codex-Max represents a big evolution in OpenAI’s technique towards agentic improvement instruments, providing larger reasoning depth, token effectivity, and interactive capabilities throughout software program engineering duties. By extending its context administration and compaction methods, the mannequin is positioned to deal with duties on the scale of full repositories, relatively than particular person recordsdata or snippets.
With continued emphasis on agentic workflows, safe sandboxes, and real-world analysis metrics, Codex-Max units the stage for the following technology of AI-assisted programming environments — whereas underscoring the significance of oversight in more and more autonomous methods.
