List of the Top 15 Large Language Models for Codex Security in 2026

OpenAI is committed to ensuring that artificial general intelligence (AGI)—characterized by its ability to perform most tasks that are economically important with a level of autonomy that surpasses human capabilities—benefits all of humanity. Our primary goal is to create AGI that is both safe and beneficial; however, we also view our mission as a success if we empower others to reach this same objective. You can take advantage of our API for numerous language-based functions, such as semantic search, summarization, sentiment analysis, content generation, translation, and much more, all achievable with just a few examples or a clear instruction in English. A simple integration gives you access to our ever-evolving AI technology, enabling you to test the API's features through these sample completions and uncover a wide array of potential uses. As you explore, you may find innovative ways to harness this technology for your projects or business needs.

GPT-5.1 Pro represents the top tier of OpenAI’s GPT-5 generation, delivering the most advanced reasoning, depth, and analytical intelligence available in ChatGPT. It is optimized for high-stakes, high-complexity scenarios where rigorous logic and verifiable accuracy are essential. Professionals use GPT-5.1 Pro for scientific research, large-scale codebases, legal reasoning, quantitative finance, data analysis, and multi-step decision workflows that exceed the capabilities of general models. With a significantly expanded context window, GPT-5.1 Pro can ingest and analyze long documents, datasets, transcripts, and multi-file projects in a single session. The model’s reasoning engine is tuned for deeper internal deliberation, enabling structured explanations, defensible conclusions, and clearer thought processes. GPT-5.1 Pro also features enhanced adherence to instructions, producing responses that are more predictable, consistent, and aligned with user goals. Compared to Instant and Thinking modes, it is built for reliability rather than speed, prioritizing quality of reasoning over quick output. While it supports most ChatGPT tools, it is intentionally restricted from Canvas and image generation to preserve dedicated compute for reasoning-heavy tasks. GPT-5.1 Pro is exclusive to ChatGPT Pro and Business subscribers, offering unlimited access within standard safety guardrails. It is the model tier best suited for users who depend on ChatGPT as a trusted research partner and analytical assistant.

Experience unmatched privacy and security with the latest version of ChatGPT, which boasts an array of advanced features. 1. The model training process does not incorporate customer data or prompts. 2. Data is protected through robust encryption methods, utilizing AES-256 for storage and TLS 1.2 or higher during transmission. 3. Adherence to SOC 2 standards is maintained for optimal compliance. 4. A user-friendly admin console streamlines the management of multiple members efficiently. 5. Enhanced security measures, including Single Sign-On (SSO) and Domain Verification, are integrated into the platform. 6. An analytics dashboard offers valuable insights into user engagement and activity trends. 7. Users benefit from unrestricted, fast access to GPT-4, along with Advanced Data Analysis capabilities*. 8. With the ability to manage 32k token context windows, users can process significantly longer inputs while preserving context. 9. Easily shareable chat templates promote effective collaboration within teams. 10. This extensive range of features guarantees that your organization operates both efficiently and with a high level of security, fostering a productive working environment. 11. The commitment to user privacy and data protection remains at the forefront of this technology's development.

OpenAI’s GPT-5 is the latest flagship AI language model, delivering unprecedented intelligence, speed, and versatility for a broad spectrum of tasks including coding, scientific inquiry, legal research, and financial analysis. It is engineered with built-in reasoning capabilities, allowing it to provide thoughtful, accurate, and context-aware responses that rival expert human knowledge. GPT-5 supports very large context windows—up to 400,000 tokens—and can generate outputs of up to 128,000 tokens, enabling complex, multi-step problem solving and long-form content creation. A novel ‘verbosity’ parameter lets users customize the length and depth of responses, while enhanced personality and steerability features improve user experience and interaction. The model integrates natively with enterprise software and cloud storage services such as Google Drive and SharePoint, leveraging company-specific data to deliver tailored insights securely and in compliance with privacy standards. GPT-5 also excels in agentic tasks, making it ideal for developers building advanced AI applications that require autonomy and multi-step decision-making. Available across ChatGPT, API, and developer tools, it transforms workflows by enabling employees to achieve expert-level results without switching between different models. Businesses can trust GPT-5 for critical work, benefiting from its safety improvements, increased accuracy, and deeper understanding. OpenAI continues to support a broad ecosystem, including specialized versions like GPT-5 mini and nano, to meet varied performance and cost needs. Overall, GPT-5 sets a new standard for AI-powered intelligence, collaboration, and productivity.

The newest version in the GPT-5 lineup, referred to as GPT-5.1, seeks to greatly improve the cognitive and conversational skills of ChatGPT. This upgrade introduces two distinct model types: GPT-5.1 Instant, which has become the favored choice due to its friendly tone, better adherence to instructions, and enhanced intelligence; conversely, GPT-5.1 Thinking has been optimized as a sophisticated reasoning engine, facilitating easier comprehension, faster responses for simpler queries, and greater diligence when addressing intricate problems. Moreover, user inquiries are now smartly routed to the model variant that is most suited for the specific task, ensuring efficiency and accuracy. This update not only enhances fundamental cognitive abilities but also fine-tunes the style of interaction, leading to models that are more pleasant to engage with and more in tune with user desires. Importantly, the system card supplement reveals that GPT-5.1 Instant features a mechanism called "adaptive reasoning," which helps it recognize when deeper contemplation is warranted before crafting its reply, while GPT-5.1 Thinking precisely tailors its reasoning duration based on the complexity of the question asked. These innovations signify a considerable leap in the quest to make AI interactions more seamless, enjoyable, and user-centric, paving the way for future developments in conversational AI technology.

The Thinking variant of GPT-5.2 stands as the highest achievement in OpenAI's GPT-5.2 series, meticulously crafted for thorough reasoning and the management of complex tasks across a diverse range of professional fields and elaborate contexts. Key improvements to the foundational GPT-5.2 framework enhance aspects such as grounding, stability, and overall reasoning quality, enabling this iteration to allocate more computational power and analytical resources to generate responses that are not only precise but also well-organized and rich in context, particularly useful when navigating intricate workflows and multi-step evaluations. With a strong emphasis on maintaining logical coherence, GPT-5.2 Thinking excels in comprehensive research synthesis, sophisticated coding and debugging, detailed data analysis, strategic planning, and high-caliber technical writing, offering a notable advantage over simpler models in scenarios that assess professional proficiency and deep knowledge. This cutting-edge model proves indispensable for experts aiming to address complex challenges with a high degree of accuracy and skill. Ultimately, GPT-5.2 Thinking redefines the capabilities expected in advanced AI applications, making it a valuable asset in today's fast-evolving professional landscape.

The GPT-5.2 Instant model is a rapid and effective evolution in OpenAI's GPT-5.2 series, specifically designed for everyday tasks and learning, and it demonstrates significant improvements in handling inquiries, offering how-to assistance, producing technical documents, and facilitating translation tasks when compared to its predecessors. This latest model expands on the engaging conversational approach seen in GPT-5.1 Instant, providing clearer explanations that emphasize key details, which allows users to access accurate answers more swiftly. Its improved speed and responsiveness enable it to efficiently manage common functions like answering questions, generating summaries, assisting with research, and supporting writing and editing endeavors, while also incorporating comprehensive advancements from the wider GPT-5.2 collection that enhance reasoning capabilities, manage lengthy contexts, and ensure factual correctness. Being part of the GPT-5.2 family, this model enjoys the benefits of collective foundational enhancements that boost its reliability and performance across a range of daily tasks. Users will find that the interaction experience is more intuitive and that they can significantly decrease the time spent looking for information. Overall, the advancements in this model not only streamline processes but also empower users to engage more effectively with technology in their daily routines.

The latest iteration of OpenAI's GPT model family, known as GPT-5.2 Pro, emerges as the pinnacle of advanced AI technology, specifically crafted to deliver outstanding reasoning abilities, manage complex tasks, and attain superior accuracy for high-stakes knowledge work, inventive problem-solving, and enterprise-level applications. This Pro version builds on the foundational improvements of the standard GPT-5.2, showcasing enhanced general intelligence, a better grasp of extended contexts, more reliable factual grounding, and optimized tool utilization, all driven by increased computational power and deeper processing capabilities to provide nuanced, trustworthy, and context-aware responses for users with intricate, multi-faceted requirements. In particular, GPT-5.2 Pro is adept at handling demanding workflows, which encompass sophisticated coding and debugging, in-depth data analysis, consolidation of research findings, meticulous document interpretation, and advanced project planning, while consistently ensuring higher accuracy and lower error rates than its less powerful variants. Consequently, this makes GPT-5.2 Pro an indispensable asset for professionals who aim to maximize their efficiency and confidently confront significant challenges in their endeavors. Moreover, its capacity to adapt to various industries further enhances its utility, making it a versatile tool for a broad range of applications.

GPT-5.1 Instant is a cutting-edge AI model designed specifically for everyday users, combining quick response capabilities with a heightened sense of conversational warmth. Its ability to adaptively reason enables it to gauge the necessary computational effort for various tasks, ensuring that responses are both timely and deeply comprehensible. By emphasizing improved adherence to instructions, users can offer detailed information and expect consistent and reliable execution. Additionally, the model incorporates expanded personality controls that allow users to tailor the chat tone to options such as Default, Friendly, Professional, Candid, Quirky, or Efficient, with ongoing experiments aimed at refining voice modulation further. The primary objective is to foster interactions that feel more natural and less robotic, all while delivering strong intelligence in writing, coding, analysis, and reasoning tasks. Moreover, GPT-5.1 Instant adeptly handles user requests through its main interface, intelligently deciding whether to utilize this version or the more intricate “Thinking” model based on the specific context of the inquiry. Furthermore, this innovative methodology significantly enhances the user experience by making communications more engaging and personalized according to individual preferences, ultimately transforming how users interact with AI.

GPT-5.1 Thinking is an advanced reasoning model within the GPT-5.1 series, designed to effectively manage "thinking time" based on the difficulty of prompts, thus facilitating faster responses to simple questions while allocating more resources to complex challenges. When compared to its predecessor, this model boasts nearly double the efficiency for straightforward tasks and requires twice the time for more intricate inquiries. It prioritizes the clarity of its answers, steering clear of jargon and ambiguous terms, which significantly improves the understanding of complex analytical tasks. The model skillfully adjusts its depth of reasoning, striking a balance between speed and thoroughness, particularly when it comes to technical topics or inquiries requiring multiple steps. By combining powerful reasoning capabilities with improved clarity, GPT-5.1 Thinking stands out as an essential tool for managing complex projects, such as detailed analyses, coding, research, or technical conversations, while also reducing wait times for simpler requests. This enhancement not only aids users in need of quick solutions but also effectively supports those engaged in higher-level cognitive tasks, making it a versatile asset in various contexts of use. Overall, GPT-5.1 Thinking represents a significant leap forward in processing efficiency and user engagement.

GPT-5.2 ushers in a significant leap forward for the GPT-5 ecosystem, redefining how the system reasons, communicates, and interprets human intent. Built on an upgraded architecture, this version refines every major cognitive dimension—from nuance detection to multi-step problem solving. A suite of enhanced variants works behind the scenes, each specialized to deliver more accuracy, coherence, and depth. GPT-5.2 Instant is engineered for speed and reliability, offering ultra-fast responses that remain highly aligned with user instructions even in complex contexts. GPT-5.2 Thinking extends the platform’s reasoning capacity, enabling more deliberate, structured, and transparent logic throughout long or sophisticated tasks. Automatic routing ensures users never need to choose a model themselves—the system selects the ideal variant based on the nature of the query. These upgrades make GPT-5.2 more adaptive, more stable, and more capable of handling nuanced, multi-intent prompts. Conversations feel more natural, with improved emotional tone matching, smoother transitions, and higher fidelity to user intent. The model also prioritizes clarity, reducing ambiguity while maintaining conversational warmth. Altogether, GPT-5.2 delivers a more intelligent, humanlike, and contextually aware AI experience for users across all domains.

GPT-5.3 Instant is an upgraded conversational model built to improve the everyday ChatGPT experience through smoother dialogue and stronger reliability. Rather than focusing solely on benchmark gains, this release emphasizes subtle but impactful qualities such as tone, conversational flow, and contextual awareness. The update reduces unnecessary refusals and trims overly cautious disclaimers, allowing responses to feel more direct and useful. It applies improved judgment in sensitive areas, striking a better balance between safety and helpfulness. Web-assisted answers have been refined to prioritize synthesis and relevance over lengthy link compilations. The model is less likely to over-rely on search results and instead integrates them thoughtfully with its existing knowledge. Accuracy has improved substantially, with measurable decreases in hallucination rates both with and without web access. Internal evaluations show particular gains in higher-stakes areas like law, finance, and medicine. GPT-5.3 Instant also strengthens its writing capabilities, producing prose that feels more textured, immersive, and emotionally controlled. These enhancements support both practical problem-solving and creative expression within the same conversational framework. The overall goal is to preserve ChatGPT’s familiar personality while delivering a more polished and capable interaction. GPT-5.3 Instant is now available to all users in ChatGPT and to developers via the API, with legacy models scheduled for phased retirement.

GPT-5.4 Pro is OpenAI’s most advanced frontier AI model designed for complex professional tasks and high-performance workflows. It combines breakthroughs in reasoning, coding, and AI agent capabilities to create a powerful system for knowledge work and software development. The model is capable of generating spreadsheets, presentations, documents, and other professional deliverables with improved accuracy and structure. GPT-5.4 Pro also introduces native computer-use capabilities, allowing AI agents to interact with applications, browsers, and operating systems. This enables the model to automate multi-step workflows such as data entry, research, and system navigation. With a context window of up to one million tokens, GPT-5.4 Pro can process large datasets and long conversations while maintaining coherence. The model also includes improved tool usage features that allow it to discover and use external tools more efficiently. Enhanced web search capabilities allow it to gather and synthesize information from multiple sources for complex research tasks. GPT-5.4 Pro builds on the coding strengths of previous Codex models while improving performance on real-world development tasks. It also reduces token consumption during reasoning, resulting in faster responses and improved cost efficiency. These advancements make it well suited for developers building AI agents or automation systems. By combining advanced reasoning, computer interaction, and scalable tool usage, GPT-5.4 Pro enables organizations and professionals to automate complex digital workflows.

GPT-5.4 Thinking is an advanced reasoning model available in ChatGPT that focuses on solving complex problems through structured analysis. Built on the GPT-5.4 architecture, it combines enhanced reasoning, coding abilities, and AI agent workflows into a single powerful system. The model is designed to assist users with demanding professional tasks such as research, document creation, data analysis, and strategic planning. One of its distinguishing features is the ability to provide an initial outline of its reasoning process before delivering the final response. This allows users to guide or refine the direction of the solution while the model is still working. GPT-5.4 Thinking also improves deep web research, enabling it to gather information from multiple sources to answer highly specific queries. The model maintains stronger context awareness during longer conversations, helping it stay aligned with the original task. These improvements allow it to handle complex workflows with greater reliability. GPT-5.4 Thinking also benefits from improvements in tool usage and integration with professional software environments. Its reasoning capabilities help reduce errors and improve the accuracy of generated outputs. This makes it suitable for tasks that require careful analysis and multi-step planning. By combining transparency in reasoning with powerful analytical capabilities, GPT-5.4 Thinking helps users achieve more precise and efficient results.

GPT-5.4 is a frontier artificial intelligence model developed by OpenAI to perform complex reasoning, coding, and knowledge-based tasks. It is designed to support professionals across industries by helping them automate workflows, analyze information, and produce detailed work outputs. The model integrates advanced reasoning capabilities with powerful coding performance derived from earlier Codex systems. GPT-5.4 can generate and edit documents, spreadsheets, presentations, and structured data used in business operations. One of its major improvements is its ability to interact with tools and external systems to complete multi-step workflows across different applications. This capability allows AI agents built on GPT-5.4 to perform tasks such as data entry, research, and automated software interactions. The model also supports extremely large context windows, enabling it to process long documents and maintain awareness across extended tasks. Improved visual understanding allows GPT-5.4 to interpret images, screenshots, and complex documents more effectively. It also introduces better web browsing and research capabilities for locating and synthesizing information online. Compared with previous versions, GPT-5.4 reduces factual errors and produces more consistent responses. Developers can access the model through APIs and integrate it into software applications, automation systems, and enterprise workflows. Overall, GPT-5.4 represents a significant step forward in AI capabilities for knowledge work, software development, and intelligent automation.