List of the Top Foundation Models for OpenAI in 2026

GPT-5.6 Luna is the lowest-cost model in OpenAI’s GPT-5.6 family, built for fast and affordable AI assistance across everyday and technical workflows. The GPT-5.6 lineup includes Sol as the flagship model, Terra as the balanced model for everyday work, and Luna as the efficient model for users who need strong capability at lower cost. Luna is intended for developers, businesses, and teams that need scalable AI for coding help, workflow automation, research support, analysis, customer-facing applications, and high-volume API usage. In the pasted preview text, Luna is presented as part of the same GPT-5.6 release process and benchmark set as Sol and Terra. It appears in evaluations for command-line coding workflows, long-horizon biology tasks, ExploitBench, and ExploitGym, indicating that it is designed to handle more than simple chat use cases. The model is priced at a lower per-token rate than Sol and Terra, making it more suitable for applications where cost efficiency is a major priority. GPT-5.6 Luna also supports the new GPT-5.6 prompt caching approach, including explicit cache breakpoints, a 30-minute minimum cache life, cache writes billed above the uncached input rate, and discounted cached-input reads. Like the rest of the GPT-5.6 family, Luna is developed with layered safeguards matched to model capability. These safeguards include trained refusals for prohibited cyber assistance, real-time misuse classifiers, paused generation for higher-risk cases, account-level review, monitoring, enforcement, automated red-teaming, and third-party human expert red-teaming. Luna is expected to support legitimate defensive and technical workflows such as code review, debugging, patch development, security education, and defensive testing while making prohibited misuse more difficult and detectable. GPT-5.6 Luna helps organizations deploy GPT-5.6-class AI where speed, affordability, scalability, and safe production use are the most important requirements.

GPT-5.6 Terra is a balanced model in OpenAI’s GPT-5.6 series, designed to provide strong performance for everyday work while keeping costs lower than the flagship Sol tier. The GPT-5.6 family includes Sol for the highest capability, Terra for balanced work, and Luna for fast and affordable use cases. Terra is positioned as a practical option for developers, businesses, and enterprise teams that need capable reasoning, coding, automation, research support, and defensive security assistance without always using the most expensive model. According to the pasted preview text, Terra offers competitive performance to GPT-5.5 while being 2x cheaper. It appears in GPT-5.6 benchmark previews for Terminal-Bench 2.1, GeneBench v1, ExploitBench, and ExploitGym, showing that the model is intended for technical and long-horizon tasks as well as general work. Terra can support coding workflows that require planning, iteration, command-line reasoning, and tool coordination. It can also support legitimate cybersecurity workflows such as code review, vulnerability research, patch development, debugging, security education, and defensive testing. The model is developed with layered safeguards matched to its capabilities, including trained refusals, real-time checks, misuse classifiers, monitoring, enforcement, and account-level review. OpenAI also describes automated red-teaming and third-party human expert red-teaming as part of the broader GPT-5.6 safety process. Terra is priced below Sol in the pasted API pricing structure, with lower input and output costs per 1 million tokens. GPT-5.6 Terra helps organizations use a capable GPT-5.6 model for production workflows where performance, cost efficiency, and safety controls all matter.

GPT-5.5 represents a new class of AI built to transform how work is done across digital environments. It combines advanced reasoning, tool usage, and task execution capabilities to manage complex, multi-step workflows with minimal human intervention. The model performs strongly in software engineering, data analysis, business operations, and scientific research, where it can plan tasks, gather information, test solutions, and refine outputs iteratively. It supports generating documents, building applications, analyzing large datasets, and navigating software systems as part of a unified workflow. A key capability is its integration with workspace agents—customizable AI agents that can be created once and deployed across teams to automate entire processes. These agents can run continuously, interact with tools like CRM systems, messaging platforms, and document editors, and keep workflows moving without constant supervision. Organizations can define permissions, approval checkpoints, and monitoring to maintain full control over automation. GPT-5.5 also improves collaboration by standardizing workflows and scaling best practices across teams. With enterprise-grade security and governance, it is designed for safe deployment in complex environments. Its ability to persist through ambiguity and long-running tasks makes it highly effective for execution-heavy work. By reducing manual intervention and increasing speed, GPT-5.5 enables teams to focus on higher-value activities and operate at a significantly higher level of productivity.

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.

The GPT-3.5 series signifies a significant leap forward in OpenAI's development of large language models, enhancing the features introduced by its predecessor, GPT-3. These models are adept at understanding and generating text that closely resembles human writing, with four key variations catering to different user needs. The fundamental models of GPT-3.5 are designed for use via the text completion endpoint, while other versions are fine-tuned for specific functionalities. Notably, the Davinci model family is recognized as the most powerful variant, adept at performing any task achievable by the other models, generally requiring less detailed guidance from users. In scenarios demanding a nuanced grasp of context, such as creating audience-specific summaries or producing imaginative content, the Davinci model typically delivers exceptional results. Nonetheless, this increased capability does come with higher resource demands, resulting in elevated costs for API access and slower processing times compared to its peers. The innovations brought by GPT-3.5 not only enhance overall performance but also broaden the scope for diverse applications, making them even more versatile for users across various industries. As a result, these advancements hold the potential to reshape how individuals and organizations interact with AI-driven text generation.

The GPT-4 model signifies a remarkable leap in artificial intelligence, functioning as a large multimodal system adept at processing both text and image inputs, while generating text outputs that enable it to address intricate problems with an accuracy that surpasses previous iterations due to its vast general knowledge and superior reasoning abilities. Available through the OpenAI API for subscribers, GPT-4 is tailored for chat-based interactions, akin to gpt-3.5-turbo, and excels in traditional completion tasks via the Chat Completions API. This cutting-edge version of GPT-4 features advancements such as enhanced instruction compliance, a JSON mode, reliable output consistency, and the capability to execute functions in parallel, rendering it an invaluable resource for developers. It is crucial to understand, however, that this preview version is not entirely equipped for high-volume production environments, having a constraint of 4,096 output tokens. Users are invited to delve into its functionalities while remaining aware of its existing restrictions, which may affect their overall experience. The ongoing updates and potential future enhancements promise to further elevate its performance and usability.

GPT-4o, with the "o" symbolizing "omni," marks a notable leap forward in human-computer interaction by supporting a variety of input types, including text, audio, images, and video, and generating outputs in these same formats. It boasts the ability to swiftly process audio inputs, achieving response times as quick as 232 milliseconds, with an average of 320 milliseconds, closely mirroring the natural flow of human conversations. In terms of overall performance, it retains the effectiveness of GPT-4 Turbo for English text and programming tasks, while significantly improving its proficiency in processing text in other languages, all while functioning at a much quicker rate and at a cost that is 50% less through the API. Moreover, GPT-4o demonstrates exceptional skills in understanding both visual and auditory data, outpacing the abilities of earlier models and establishing itself as a formidable asset for multi-modal interactions. This groundbreaking model not only enhances communication efficiency but also expands the potential for diverse applications across various industries. As technology continues to evolve, the implications of such advancements could reshape the future of user interaction in multifaceted ways.

GPT-4.5 marks a substantial leap forward in artificial intelligence, building upon its predecessors by enhancing its unsupervised learning methods, honing its reasoning capabilities, and improving its collaborative functionalities. Designed to better interpret human intentions, this model enables more fluid and instinctive interactions, leading to increased precision and fewer instances of misinformation across a wide range of topics. Its advanced capabilities not only foster the generation of creative and intellectually stimulating content but also aid in tackling complex problems while offering assistance in various domains such as writing, design, and even aerospace endeavors. In addition, the model's improved human engagement opens doors for practical applications, making it more user-friendly and reliable for both businesses and developers. As it continues to innovate, GPT-4.5 establishes a new benchmark for the role of AI in numerous sectors and applications, demonstrating its potential to transform how we approach technology in everyday life. The ongoing developments in this field suggest a promising future where AI can seamlessly integrate into our daily routines and professional tasks.

GPT-4.1 is a cutting-edge AI model from OpenAI, offering major advancements in performance, especially for tasks requiring complex reasoning and large context comprehension. With the ability to process up to 1 million tokens, GPT-4.1 delivers more accurate and reliable results for tasks like software coding, multi-document analysis, and real-time problem-solving. Compared to its predecessors, GPT-4.1 excels in instruction following and coding tasks, offering higher efficiency and improved performance at a reduced cost.

A streamlined model that excels in both text comprehension and multimodal reasoning abilities. The GPT-4o mini has been crafted to efficiently manage a vast range of tasks, characterized by its affordability and quick response times, which make it particularly suitable for scenarios requiring the simultaneous execution of multiple model calls, such as activating various APIs at once, analyzing large sets of information like complete codebases or lengthy conversation histories, and delivering prompt, real-time text interactions for customer support chatbots. At present, the API for GPT-4o mini supports both textual and visual inputs, with future enhancements planned to incorporate support for text, images, videos, and audio. This model features an impressive context window of 128K tokens and can produce outputs of up to 16K tokens per request, all while maintaining a knowledge base that is updated to October 2023. Furthermore, the advanced tokenizer utilized in GPT-4o enhances its efficiency in handling non-English text, thus expanding its applicability across a wider range of uses. Consequently, the GPT-4o mini is recognized as an adaptable resource for developers and enterprises, making it a valuable asset in various technological endeavors. Its flexibility and efficiency position it as a leader in the evolving landscape of AI-driven solutions.

The o1-pro from OpenAI is a more sophisticated version of the original o1 model, designed to tackle complex and demanding challenges with greater reliability. This enhanced model exhibits significant improvements over the prior o1 preview, achieving an impressive 34% reduction in critical errors and a 50% boost in processing speed. It excels in areas such as mathematics, physics, and programming, providing detailed and accurate solutions. Additionally, the o1-pro can handle multimodal inputs, including both text and images, and demonstrates exceptional skills in complex reasoning tasks that require deep analytical thinking. It is accessible through a ChatGPT Pro subscription, granting users not just unlimited access, but also enhanced functionalities for those in need of advanced AI assistance. With these capabilities, users are empowered to efficiently and effectively tackle a broader array of challenges, making the o1-pro an invaluable tool for problem-solving. Overall, the advancements in this model signify a leap forward in AI technology, offering new possibilities for various applications.

The recent development of GPT-4 with vision (GPT-4V) empowers users to instruct GPT-4 to analyze image inputs they submit, representing a pivotal advancement in enhancing its capabilities. Experts in the domain regard the fusion of different modalities, such as images, with large language models (LLMs) as an essential facet for future advancements in artificial intelligence. By incorporating these multimodal features, LLMs have the potential to improve the efficiency of conventional language systems, leading to the creation of novel interfaces and user experiences while addressing a wider spectrum of tasks. This system card is dedicated to evaluating the safety measures associated with GPT-4V, building on the existing safety protocols established for its predecessor, GPT-4. In this document, we explore in greater detail the assessments, preparations, and methodologies designed to ensure safety in relation to image inputs, thereby underscoring our dedication to the responsible advancement of AI technology. Such initiatives not only protect users but also facilitate the ethical implementation of AI breakthroughs, ensuring that innovations align with societal values and ethical standards. Moreover, the pursuit of safety in AI systems is vital for fostering trust and reliability in their applications.

OpenAI has unveiled the o1 series, which heralds a new era of AI models tailored to improve reasoning abilities. This series includes models such as o1-preview and o1-mini, which implement a cutting-edge reinforcement learning strategy that prompts them to invest additional time "thinking" through various challenges prior to providing answers. This approach allows the o1 models to excel in complex problem-solving environments, especially in disciplines like coding, mathematics, and science, where they have demonstrated superiority over previous iterations like GPT-4o in certain benchmarks. The purpose of the o1 series is to tackle issues that require deeper cognitive engagement, marking a significant step forward in developing AI systems that can reason more like humans do. Currently, the series is still in the process of refinement and evaluation, showcasing OpenAI's dedication to the ongoing enhancement of these technologies. As the o1 models evolve, they underscore the promising trajectory of AI, illustrating its capacity to adapt and fulfill increasingly sophisticated requirements in the future. This ongoing innovation signifies a commitment not only to technological advancement but also to addressing real-world challenges with more effective AI solutions.

The o1-mini, developed by OpenAI, represents a cost-effective innovation in AI, focusing on enhanced reasoning skills particularly in STEM fields like math and programming. As part of the o1 series, this model is designed to address complex problems by spending more time on analysis and thoughtful solution development. Despite being smaller and priced at 80% less than the o1-preview model, the o1-mini proves to be quite powerful in handling coding tasks and mathematical reasoning. This effectiveness makes it a desirable option for both developers and businesses looking for dependable AI solutions. Additionally, its economical price point ensures that a broader audience can access and leverage advanced AI technology without sacrificing quality. Overall, the o1-mini stands out as a remarkable tool for those needing efficient support in technical areas.

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.

GPT-4.1 mini is a more lightweight version of the GPT-4.1 model, designed to offer faster response times and reduced latency, making it an excellent choice for applications that require real-time AI interaction. Despite its smaller size, GPT-4.1 mini retains the core capabilities of the full GPT-4.1 model, including handling up to 1 million tokens of context and excelling at tasks like coding and instruction following. With significant improvements in efficiency and cost-effectiveness, GPT-4.1 mini is ideal for developers and businesses looking for powerful, low-latency AI solutions.

GPT-4.1 nano is a highly efficient, smaller-scale version of the GPT-4.1 model, built for high-speed, low-cost AI applications. It retains the core capabilities of the GPT-4.1 series, including support for a 1 million token context window, but with optimized performance for tasks like classification, search, and autocompletion. Designed to be both affordable and fast, GPT-4.1 nano is perfect for developers and businesses looking for a quick, reliable AI solution that minimizes latency and operational costs.

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.

MiniMax M2 represents a revolutionary open-source foundational model specifically designed for agent-driven applications and coding endeavors, striking a remarkable balance between efficiency, speed, and cost-effectiveness. It excels within comprehensive development ecosystems, skillfully handling programming assignments, utilizing various tools, and executing complex multi-step operations, all while seamlessly integrating with Python and delivering impressive inference speeds estimated at around 100 tokens per second, coupled with competitive API pricing at roughly 8% of comparable proprietary models. Additionally, the model features a "Lightning Mode" for rapid and efficient agent actions and a "Pro Mode" tailored for in-depth full-stack development, report generation, and management of web-based tools; its completely open-source weights facilitate local deployment through vLLM or SGLang. What sets MiniMax M2 apart is its readiness for production environments, enabling agents to independently carry out tasks such as data analysis, software development, tool integration, and executing complex multi-step logic in real-world organizational settings. Furthermore, with its cutting-edge capabilities, this model is positioned to transform how developers tackle intricate programming challenges and enhances productivity across various domains.

GPT-5.5 Pro represents a new class of AI designed to transform how work gets done across digital environments. It combines advanced reasoning, tool usage, and task execution capabilities to handle complex, multi-step workflows with minimal human intervention. The model excels in areas such as software engineering, data analysis, business operations, and scientific research, where it can plan tasks, gather information, test solutions, and refine outputs continuously. It supports creating applications, generating reports, building spreadsheets, and navigating software systems as part of a complete workflow. A key capability is its integration with workspace agents—custom AI agents that can be built once and deployed across teams to automate entire processes. These agents can run tasks on schedules, interact with tools like CRM systems, messaging platforms, and document editors, and keep workflows moving without constant supervision. Organizations can define permissions, approval checkpoints, and monitoring to maintain control over automated processes. GPT-5.5 Pro also enhances collaboration by enabling teams to standardize workflows and scale best practices across the organization. With enterprise-grade security and governance, it ensures safe deployment in complex environments. Its ability to persist through ambiguity and long tasks makes it highly effective for execution-heavy work. By reducing manual intervention and increasing speed, it allows teams to focus on higher-value activities. Ultimately, GPT-5.5 Pro enables businesses and professionals to operate at a significantly higher level of productivity and efficiency.

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.

OpenAI o3 represents a state-of-the-art AI model designed to enhance reasoning skills by breaking down intricate tasks into simpler, more manageable pieces. It demonstrates significant improvements over previous AI iterations, especially in domains such as programming, competitive coding challenges, and excelling in mathematical and scientific evaluations. OpenAI o3 is available for public use, thereby enabling sophisticated AI-driven problem-solving and informed decision-making. The model utilizes deliberative alignment techniques to ensure that its outputs comply with established safety and ethical guidelines, making it an essential tool for developers, researchers, and enterprises looking to explore groundbreaking AI innovations. With its advanced features, OpenAI o3 is poised to transform the landscape of artificial intelligence applications across a wide range of sectors, paving the way for future developments and enhancements. Its impact on the industry could lead to even more refined AI capabilities in the years to come.

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.