List of the Top 18 Large Language Models for OpenAI Codex in 2026

ChatGPT is a state-of-the-art conversational AI developed by OpenAI, designed to assist users in a wide variety of tasks including creative writing, studying, brainstorming, coding, data analysis, and more. The platform is freely accessible online with additional subscription tiers—Plus and Pro—that provide enhanced capabilities such as access to the latest AI models (GPT-4o, OpenAI o1 pro), extended usage limits, and advanced voice and video features. ChatGPT supports multimodal interaction, allowing users to type or speak commands and receive instant, contextually relevant responses. Integrated tools such as DALL·E 3 enable users to generate images from text prompts, while Canvas supports collaborative writing and code editing. It also incorporates real-time web search to deliver up-to-date information and a research preview for deep exploratory tasks. With customizable GPTs, users can tailor the AI’s behavior to specific needs, and advanced projects allow managing workflows and tasks efficiently. ChatGPT is designed for a broad audience including students, educators, content creators, developers, and enterprises looking to enhance productivity and creativity through AI augmentation. OpenAI maintains a strong commitment to safety, privacy, and transparency, ensuring secure and ethical AI usage. The platform’s seamless cross-device availability allows users to work and interact effortlessly anywhere. Regular updates and new feature releases keep ChatGPT at the forefront of AI innovation and user experience.

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.

Our models are crafted to understand and generate natural language effectively. We offer four main models, each designed with different complexities and speeds to meet a variety of needs. Among these options, Davinci emerges as the most robust, while Ada is known for its remarkable speed. The principal GPT-3 models are mainly focused on the text completion endpoint, yet we also provide specific models that are fine-tuned for other endpoints. Not only is Davinci the most advanced in its lineup, but it also performs tasks with minimal direction compared to its counterparts. For tasks that require a nuanced understanding of content, like customized summarization and creative writing, Davinci reliably produces outstanding results. Nevertheless, its superior capabilities come at the cost of requiring more computational power, which leads to higher expenses per API call and slower response times when compared to other models. Consequently, the choice of model should align with the particular demands of the task in question, ensuring optimal performance for the user's needs. Ultimately, understanding the strengths and limitations of each model is essential for achieving the best results.

The fourth iteration of the Generative Pre-trained Transformer, known as GPT-4, is an advanced language model expected to be launched by OpenAI. As the next generation following GPT-3, it is part of the series of models designed for natural language processing and has been built on an extensive dataset of 45TB of text, allowing it to produce and understand language in a way that closely resembles human interaction. Unlike traditional natural language processing models, GPT-4 does not require additional training on specific datasets for particular tasks. It generates responses and creates context solely based on its internal mechanisms. This remarkable capacity enables GPT-4 to perform a wide range of functions, including translation, summarization, answering questions, sentiment analysis, and more, all without the need for specialized training for each task. The model’s ability to handle such a variety of applications underscores its significant potential to influence advancements in artificial intelligence and natural language processing fields. Furthermore, as it continues to evolve, GPT-4 may pave the way for even more sophisticated applications in the future.

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.

Leverage advanced coding and linguistic models across a wide range of applications. Tap into the capabilities of extensive generative AI models that offer a profound understanding of both language and programming, facilitating innovative reasoning and comprehension essential for creating cutting-edge applications. These models find utility in various areas, such as writing assistance, code generation, and data analytics, all while adhering to responsible AI guidelines to mitigate any potential misuse, supported by robust Azure security measures. Utilize generative models that have been exposed to extensive datasets, enabling their use in multiple contexts like language processing, coding assignments, logical reasoning, inferencing, and understanding. Customize these generative models to suit your specific requirements by employing labeled datasets through an easy-to-use REST API. You can improve the accuracy of your outputs by refining the model’s hyperparameters and applying few-shot learning strategies to provide the API with examples, resulting in more relevant outputs and ultimately boosting application effectiveness. By implementing appropriate configurations and optimizations, you can significantly enhance your application's performance while ensuring a commitment to ethical practices in AI application. Additionally, the continuous evolution of these models allows for ongoing improvements, keeping pace with advancements in technology.

GPT-5 mini is a faster, more affordable variant of OpenAI’s advanced GPT-5 language model, specifically tailored for well-defined and precise tasks that benefit from high reasoning ability. It accepts both text and image inputs (image input only), and generates high-quality text outputs, supported by a large 400,000-token context window and a maximum of 128,000 tokens in output, enabling complex multi-step reasoning and detailed responses. The model excels in providing rapid response times, making it ideal for use cases where speed and efficiency are critical, such as chatbots, customer service, or real-time analytics. GPT-5 mini’s pricing structure significantly reduces costs, with input tokens priced at $0.25 per million and output tokens at $2 per million, offering a more economical option compared to the flagship GPT-5. While it supports advanced features like streaming, function calling, structured output generation, and fine-tuning, it does not currently support audio input or image generation capabilities. GPT-5 mini integrates seamlessly with multiple API endpoints including chat completions, responses, embeddings, and batch processing, providing versatility for a wide array of applications. Rate limits are tier-based, scaling from 500 requests per minute up to 30,000 per minute for higher tiers, accommodating small to large scale deployments. The model also supports snapshots to lock in performance and behavior, ensuring consistency across applications. GPT-5 mini is ideal for developers and businesses seeking a cost-effective solution with high reasoning power and fast throughput. It balances cutting-edge AI capabilities with efficiency, making it a practical choice for applications demanding speed, precision, and scalability.

GPT-5 nano is OpenAI’s fastest and most cost-efficient version of the GPT-5 model, engineered to handle high-speed text and image input processing for tasks such as summarization, classification, and content generation. It features an extensive 400,000-token context window and can output up to 128,000 tokens, allowing for complex, multi-step language understanding despite its focus on speed. With ultra-low pricing—$0.05 per million input tokens and $0.40 per million output tokens—GPT-5 nano makes advanced AI accessible to budget-conscious users and developers working at scale. The model supports a variety of advanced API features, including streaming output, function calling for interactive applications, structured outputs for precise control, and fine-tuning for customization. While it lacks support for audio input and web search, GPT-5 nano supports image input, code interpretation, and file search, broadening its utility. Developers benefit from tiered rate limits that scale from 500 to 30,000 requests per minute and up to 180 million tokens per minute, supporting everything from small projects to enterprise workloads. The model also offers snapshots to lock performance and behavior, ensuring consistent results over time. GPT-5 nano strikes a practical balance between speed, cost, and capability, making it ideal for fast, efficient AI implementations where rapid turnaround and budget are critical. It fits well for applications requiring real-time summarization, classification, chatbots, or lightweight natural language processing tasks. Overall, GPT-5 nano expands the accessibility of OpenAI’s powerful AI technology to a broader user base.

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 Pro is OpenAI’s flagship AI model built to deliver exceptional reasoning power and precision for the most complex and nuanced problems across numerous domains. Utilizing advanced parallel computing techniques, it extends the GPT-5 architecture to think longer and more deeply, resulting in highly accurate and comprehensive responses on challenging tasks such as advanced science, health diagnostics, coding, and mathematics. This model consistently outperforms its predecessors on rigorous benchmarks like GPQA and expert evaluations, reducing major errors by 22% and gaining preference from external experts nearly 68% of the time over GPT-5 thinking. GPT-5 Pro is designed to adapt dynamically, determining when to engage extended reasoning for queries that benefit from it while balancing speed and depth. Beyond its technical prowess, it incorporates enhanced safety features, lowering hallucination rates and providing transparent communication when limits are reached or tasks cannot be completed. The model supports Pro users with unlimited access and integrates seamlessly into ChatGPT’s ecosystem, including Codex CLI for coding applications. GPT-5 Pro also benefits from improvements in reducing excessive agreeableness and sycophancy, making interactions feel natural and thoughtful. With extensive red-teaming and rigorous safety protocols, it is prepared to handle sensitive and high-stakes use cases responsibly. This model is ideal for researchers, developers, and professionals seeking the most reliable, insightful, and powerful AI assistant. GPT-5 Pro marks a major step forward in AI’s ability to augment human intelligence across complex real-world challenges.

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 marks a significant step forward in the GPT-5 series, delivering greater intelligence, adaptability, and conversational refinement. The release introduces upgraded model variants designed to enhance both speed and depth of reasoning. GPT-5.3 Instant acts as the primary high-throughput model, optimized for rapid responses, improved context retention, and precise instruction-following. For more demanding scenarios, GPT-5.3 Thinking offers expanded analytical strength, producing clearer logical breakdowns and more reliable multi-stage problem solving. These variants work together within a unified system that automatically routes each request to the most suitable model. This intelligent routing ensures that straightforward queries receive fast answers while complex tasks benefit from deeper reasoning power. GPT-5.3 also improves consistency across long conversations, maintaining context and coherence more effectively. Enhanced intent recognition allows it to better interpret subtle user goals and nuanced instructions. The model demonstrates stronger alignment between user prompts and generated outputs, reducing ambiguity and misunderstandings. Communication style has been refined to sound more fluid, conversational, and naturally structured. Improvements in adaptability enable GPT-5.3 to adjust tone and depth based on context. Altogether, GPT-5.3 delivers a more intelligent, responsive, and humanlike AI interaction experience.