List of the Top 25 Foundation Models for StackAI in 2026

Claude Opus 5 is Anthropic’s advanced Opus model designed for high-value coding, knowledge work, problem-solving, automation, scientific research, and everyday AI workflows. The model is positioned as a thoughtful and proactive system that approaches the frontier intelligence of Claude Fable 5 at half the price. Anthropic says Claude Opus 5 delivers greatly improved performance for the same cost as Opus 4.8, with base pricing of $5 per million input tokens and $25 per million output tokens. The model supports effort settings that allow customers to optimize for deeper intelligence or conserve tokens for faster and cheaper results. Claude Opus 5 performs especially well on software engineering evaluations, including tasks that require debugging, code generation, root-cause analysis, test creation, and multi-step implementation. It also shows strong results on knowledge work, business automation, computer use, novel problem solving, and research-heavy tasks. Anthropic highlights that Opus 5 is better at checking its own work, iterating until it succeeds, and building supporting tools when a task requires it. The model improves on Opus 4.8 across life sciences evaluations, including structural biology, organic chemistry, bioinformatics, molecular structure inference, and protein function tasks. Claude Opus 5 includes alignment and safety protections that aim to allow beneficial cybersecurity and biology use cases while restricting riskier exploit generation, penetration testing, and certain autonomous misuse scenarios. It is available on Claude Max as the default model, on Claude Pro as the strongest model, and through the Claude API as claude-opus-5, with a Fast mode that runs around 2.5 times the default speed.

Claude Fable 5 is a frontier AI model developed by Anthropic to deliver advanced reasoning, coding, research, and multimodal capabilities for enterprise and professional users. As a Mythos-class model adapted for broad availability, it combines high-level intelligence with safety-focused deployment controls. The model excels at software engineering tasks, including large-scale code analysis, migrations, debugging, architecture review, and autonomous project execution. Claude Fable 5 also demonstrates strong performance in knowledge work, helping users analyze documents, evaluate financial information, interpret charts and tables, conduct research, and generate actionable insights. Its vision capabilities enable sophisticated image understanding, visual reasoning, and screenshot-based analysis. The model supports long-context workflows and persistent memory utilization, allowing it to work effectively on extended tasks involving millions of tokens of information. Anthropic has implemented a layered safety framework that includes specialized classifiers for cybersecurity, biology, chemistry, and model distillation-related requests. When these areas are detected, requests may be handled by a different model with stricter operational controls. Claude Fable 5 is available through the Claude API and Anthropic’s product ecosystem, providing developers and enterprises with access to advanced AI-powered assistance. The model is designed to enhance productivity, accelerate research, improve software development workflows, and support complex analytical tasks. By combining powerful reasoning, multimodal intelligence, and enterprise-focused safeguards, Claude Fable 5 enables organizations to scale AI adoption responsibly and effectively.

Claude Mythos 5 is Anthropic’s restricted-access Mythos-class AI model built for trusted organizations that require the highest level of Claude capability. The model shares the same underlying architecture as Claude Fable 5, but is offered with certain safeguards removed for approved use cases and vetted users. Claude Mythos 5 is designed for advanced cybersecurity, software engineering, scientific discovery, long-context reasoning, and autonomous research workflows. It is initially deployed through Project Glasswing for cyberdefenders and critical infrastructure providers. The model is intended to help security teams analyze complex systems, support defensive cybersecurity work, and protect important software environments. Claude Mythos 5 also demonstrates major potential in life sciences, where it can assist with protein design, binding-site selection, bioinformatics workflows, and research hypothesis generation. Anthropic reports that the model can carry out extended technical tasks, recover from failures, and operate with a high degree of autonomy. Its capabilities in genomics include assembling large-scale single-cell datasets and designing custom machine learning approaches for biological research. Because these capabilities may be dual-use, Anthropic limits access through trusted programs and applies a 30-day retention policy for Mythos-class traffic. The model is priced at $10 per million input tokens and $50 per million output tokens. Claude Mythos 5 helps vetted organizations apply frontier AI to critical defense, infrastructure, and scientific problems while maintaining controlled access and oversight.

Claude Opus 4.8 is Anthropic’s latest frontier AI model engineered to deliver advanced coding intelligence, reasoning capabilities, autonomous workflows, and enterprise-grade collaboration for developers, technical teams, and organizations building AI-powered systems. As the successor to Claude Opus 4.7, the model introduces improvements across software engineering, agentic execution, practical knowledge work, benchmark performance, and alignment behavior while retaining the same standard pricing structure. Claude Opus 4.8 is specifically optimized for complex coding tasks, large-scale workflow orchestration, long-running automation processes, and advanced reasoning scenarios where reliability, transparency, and contextual judgment are critical. One of the model’s defining advancements is its improved honesty and uncertainty awareness, making it significantly less likely to produce unsupported conclusions or overlook defects in generated code, reasoning chains, and operational outputs. Anthropic’s alignment assessments also report stronger prosocial behavior, lower rates of deceptive or unsafe actions, and improved adherence to user intent compared to earlier Opus releases. The release introduces configurable effort controls that allow users to determine how much computational reasoning the model applies to a task, enabling flexible tradeoffs between speed, token consumption, and response depth depending on workflow complexity. Claude Opus 4.8 also powers new “dynamic workflows” functionality in Claude Code, where the model can coordinate hundreds of parallel AI subagents during a single session to execute large-scale software engineering operations such as repository-wide migrations, testing workflows, and multi-step automation tasks. Anthropic further expanded the platform with lower-cost fast mode processing, enabling the model to operate at significantly higher speeds while remaining more affordable than previous high-performance configurations.

Claude is a powerful AI assistant designed by Anthropic to support problem-solving, creativity, and productivity across a wide range of use cases. It helps users write, edit, analyze, and code by combining conversational AI with advanced reasoning capabilities. Claude allows users to work on documents, software, graphics, and structured data directly within the chat experience. Through features like Artifacts, users can collaborate with Claude to iteratively build and refine projects. The platform supports file uploads, image understanding, and data visualization to enhance how information is processed and presented. Claude also integrates web search results into conversations to provide timely and relevant context. Available on web, iOS, and Android, Claude fits seamlessly into modern workflows. Multiple subscription tiers offer flexibility, from free access to high-usage professional and enterprise plans. Advanced models give users greater depth, speed, and reasoning power for complex tasks. Claude is built with enterprise-grade security and privacy controls to protect sensitive information. Anthropic prioritizes transparency and responsible scaling in Claude’s development. As a result, Claude is positioned as a trusted AI assistant for both everyday tasks and mission-critical work.

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.

Mistral AI is recognized as a pioneering startup in the field of artificial intelligence, with a particular emphasis on open-source generative technologies. The company offers a wide range of customizable, enterprise-grade AI solutions that can be deployed across multiple environments, including on-premises, cloud, edge, and individual devices. Notable among their offerings are "Le Chat," a multilingual AI assistant designed to enhance productivity in both personal and business contexts, and "La Plateforme," a resource for developers that streamlines the creation and implementation of AI-powered applications. Mistral AI's unwavering dedication to transparency and innovative practices has enabled it to carve out a significant niche as an independent AI laboratory, where it plays an active role in the evolution of open-source AI while also influencing relevant policy conversations. By championing the development of an open AI ecosystem, Mistral AI not only contributes to technological advancements but also positions itself as a leading voice within the industry, shaping the future of artificial intelligence. This commitment to fostering collaboration and openness within the AI community further solidifies its reputation as a forward-thinking organization.

Grok is an AI-powered assistant developed by xAI, designed to provide real-time, context-aware, and engaging conversational experiences. It is tightly integrated with the X platform, allowing it to access live data, trending topics, and user-generated content for up-to-date insights. Grok is built to handle a variety of tasks, including research, content generation, problem-solving, and general inquiries. Its advanced language model enables it to understand complex questions and deliver accurate, thoughtful responses. Unlike traditional AI tools, Grok incorporates humor and personality, making interactions more engaging and human-like. The platform is particularly effective for tracking current events and social trends in real time. It supports both casual and professional use cases, offering flexibility for different user needs. Grok continuously improves through updates, enhancing its reasoning and conversational abilities. It is designed to be intuitive and easy to use within the X ecosystem. The integration with live data makes it highly relevant for fast-changing information environments. Security and performance are key priorities, ensuring reliable interactions. Overall, Grok represents a next-generation AI assistant focused on real-time intelligence and engaging user experiences.

Claude Sonnet 3.5 from Anthropic is a highly efficient AI model that excels in key areas like graduate-level reasoning (GPQA), undergraduate knowledge (MMLU), and coding proficiency (HumanEval). It significantly outperforms previous models in grasping nuance, humor, and following complex instructions, while producing content with a conversational and relatable tone. With a performance speed twice that of Claude Opus 3, this model is optimized for complex tasks such as orchestrating workflows and providing context-sensitive customer support.

Opus stands out as our leading model, outpacing rival systems across a variety of key metrics used to evaluate artificial intelligence, such as the assessment of undergraduate-level expertise (MMLU), graduate reasoning capabilities (GPQA), and essential mathematics skills (GSM8K), among others. Its exceptional performance is akin to human understanding and fluency when tackling complex challenges, placing it at the cutting edge of developments in general intelligence. Additionally, all Claude 3 models exhibit improved proficiency in analysis and forecasting, advanced content generation, coding, and conversing in multiple languages beyond English, including Spanish, Japanese, and French, highlighting their adaptability in communication. This remarkable versatility not only enhances user interaction but also broadens the potential applications of these models in diverse fields.

Claude Sonnet 3.7, created by Anthropic, is an innovative AI model that brings a unique approach to problem-solving by balancing rapid responses with deep reflective reasoning. This hybrid capability allows users to toggle between quick, efficient answers for everyday tasks and more thoughtful, reflective responses for complex challenges. Its advanced reasoning capabilities make it ideal for tasks like coding, natural language processing, and critical thinking, where nuanced understanding is essential. The ability to pause and reflect before providing an answer helps Claude Sonnet 3.7 tackle intricate problems more effectively, offering professionals and organizations a powerful AI tool that adapts to their specific needs for both speed and accuracy.

Claude Opus 4, the most advanced model in the Claude family, is built to handle the most complex software engineering tasks with ease. It outperforms all previous models, including Sonnet, with exceptional benchmarks in coding precision, debugging, and complex multi-step workflows. Opus 4 is tailored for developers and teams who need a high-performance AI that can tackle challenges over extended periods—perfect for real-time collaboration and long-duration tasks. Its efficiency in multi-agent workflows and problem-solving makes it ideal for companies looking to integrate AI into their development process for sustained impact. Available via the Anthropic API, Amazon Bedrock, and Gemini Enterprise Agent Platform, Opus 4 offers a robust tool for teams working on cutting-edge software development and research.

Claude Opus 4.7 represents a major step forward in AI model development, focusing on advanced reasoning, coding, and enterprise-level task execution. It improves significantly over Opus 4.6 by delivering stronger performance on complex and high-effort software engineering challenges. The model is particularly effective at managing long-running processes, maintaining consistency, and producing reliable outputs over time. Its enhanced instruction-following capabilities ensure that it interprets prompts more literally and executes tasks with greater precision. Opus 4.7 also features advanced self-checking mechanisms, enabling it to validate its own responses before completion. A major highlight is its improved multimodal support, allowing it to process high-resolution images and extract fine visual details. This capability is especially useful for tasks like analyzing technical screenshots, interpreting diagrams, and supporting computer-based workflows. The model produces high-quality professional outputs, including refined documents, presentations, and UI designs that meet business standards. It also demonstrates strong performance across industries such as finance, legal services, and data analysis. Enhanced memory capabilities allow it to retain important context across sessions, making it more efficient for ongoing projects. Opus 4.7 includes safety and alignment improvements, with systems in place to detect and block potentially harmful or restricted use cases. It introduces new controls for balancing reasoning depth and response speed, giving users flexibility based on task complexity. Widely accessible through APIs and major cloud platforms, Opus 4.7 is designed to support scalable, high-performance AI applications for modern enterprises.

Claude Sonnet 4 is a breakthrough AI model, refining the strengths of Claude Sonnet 3.7 and delivering impressive results across software engineering tasks, coding, and advanced reasoning. With a robust 72.7% on SWE-bench, Sonnet 4 demonstrates remarkable improvements in handling complex tasks, clearer reasoning, and more effective code optimization. The model’s ability to execute complex instructions with higher accuracy and navigate intricate codebases with fewer errors makes it indispensable for developers. Whether for app development or addressing sophisticated software engineering challenges, Sonnet 4 balances performance and efficiency, offering an optimal solution for enterprises and individual developers seeking high-quality AI assistance.

Claude Haiku 3.5 is the next evolution in AI, combining speed, advanced reasoning, and powerful coding capabilities—all at a cost-effective price. Compared to its predecessor, Claude Haiku 3, this model delivers faster processing while surpassing the capabilities of Claude Opus 3, the previous largest model, on key intelligence benchmarks. Developers and businesses alike will benefit from its enhanced tool use, precise reasoning, and swift task execution. With text-only capabilities currently available, and plans for image input support in the future, Haiku 3.5 is the ideal solution for those looking for rapid, reliable, and efficient AI-powered support across various platforms.

Claude Opus 4.6 is an advanced AI language model developed by Anthropic, designed to handle complex reasoning, coding, and enterprise-level tasks with high accuracy. It introduces major improvements in planning, debugging, and code review, making it highly effective for software development workflows. The model is capable of sustaining long-running, agentic tasks and performing reliably across large and complex codebases. A key feature of Claude Opus 4.6 is its 1 million token context window in beta, enabling it to process vast amounts of information while maintaining coherence. It excels in knowledge work tasks such as financial analysis, research, and document creation. The model achieves state-of-the-art performance on multiple benchmarks, including coding and reasoning evaluations. Claude Opus 4.6 includes adaptive thinking, allowing it to dynamically adjust how deeply it reasons based on context. Developers can fine-tune performance using configurable effort levels that balance intelligence, speed, and cost. The model also supports context compaction, enabling longer workflows without exceeding limits. Integration with tools like Excel and PowerPoint enhances its usability for everyday business tasks. It maintains a strong safety profile with low rates of misaligned behavior and improved reliability. Overall, Claude Opus 4.6 is a powerful AI solution for advanced technical, analytical, and enterprise applications.

Claude Sonnet 4.6 is the latest evolution in Anthropic’s Sonnet model family, offering major advancements in coding, reasoning, computer interaction, and knowledge-intensive workflows. Designed as a full upgrade rather than an incremental update, it improves consistency, instruction following, and multi-step task completion across a broad range of professional applications. The model introduces a 1 million token context window in beta, enabling users to analyze entire codebases, long contracts, research archives, or complex planning documents in one cohesive session. Developers with early access reported a strong preference for Sonnet 4.6 over Sonnet 4.5 and even favored it over Opus 4.5 in many real-world coding tasks. Users highlighted its reduced overengineering tendencies, improved follow-through, and lower incidence of hallucinations during extended sessions. A major enhancement is its improved computer-use capability, allowing it to operate traditional software environments by interacting with graphical interfaces much like a human user. On benchmarks such as OSWorld, Sonnet models have shown steady gains in handling browser navigation, spreadsheets, and development tools. The model also demonstrates strategic reasoning improvements in long-horizon simulations, such as Vending-Bench Arena, where it optimizes early investments before pivoting toward profitability. On the Claude Developer Platform, Sonnet 4.6 supports adaptive thinking, extended thinking, and context compaction to maximize usable context length. API enhancements now include automated search filtering, code execution, memory, and advanced tool use capabilities for higher-quality outputs. Pricing remains consistent with Sonnet 4.5, making Opus-level performance more accessible to a broader user base. Available across Claude.ai, Cowork, Claude Code, the API, and major cloud platforms, Sonnet 4.6 becomes the new default model for Free and Pro users.

Mistral 7B is a cutting-edge language model boasting 7.3 billion parameters, which excels in various benchmarks, even surpassing larger models such as Llama 2 13B. It employs advanced methods like Grouped-Query Attention (GQA) to enhance inference speed and Sliding Window Attention (SWA) to effectively handle extensive sequences. Available under the Apache 2.0 license, Mistral 7B can be deployed across multiple platforms, including local infrastructures and major cloud services. Additionally, a unique variant called Mistral 7B Instruct has demonstrated exceptional abilities in task execution, consistently outperforming rivals like Llama 2 13B Chat in certain applications. This adaptability and performance make Mistral 7B a compelling choice for both developers and researchers seeking efficient solutions. Its innovative features and strong results highlight the model's potential impact on natural language processing projects.

We are excited to unveil Mistral NeMo, our latest and most sophisticated small model, boasting an impressive 12 billion parameters and a vast context length of 128,000 tokens, all available under the Apache 2.0 license. In collaboration with NVIDIA, Mistral NeMo stands out in its category for its exceptional reasoning capabilities, extensive world knowledge, and coding skills. Its architecture adheres to established industry standards, ensuring it is user-friendly and serves as a smooth transition for those currently using Mistral 7B. To encourage adoption by researchers and businesses alike, we are providing both pre-trained base models and instruction-tuned checkpoints, all under the Apache license. A remarkable feature of Mistral NeMo is its quantization awareness, which enables FP8 inference while maintaining high performance levels. Additionally, the model is well-suited for a range of global applications, showcasing its ability in function calling and offering a significant context window. When benchmarked against Mistral 7B, Mistral NeMo demonstrates a marked improvement in comprehending and executing intricate instructions, highlighting its advanced reasoning abilities and capacity to handle complex multi-turn dialogues. Furthermore, its design not only enhances its performance but also positions it as a formidable option for multi-lingual tasks, ensuring it meets the diverse needs of various use cases while paving the way for future innovations.

Mistral Large is the flagship language model developed by Mistral AI, designed for advanced text generation and complex multilingual reasoning tasks including text understanding, transformation, and software code creation. It supports various languages such as English, French, Spanish, German, and Italian, enabling it to effectively navigate grammatical complexities and cultural subtleties. With a remarkable context window of 32,000 tokens, Mistral Large can accurately retain and reference information from extensive documents. Its proficiency in following precise instructions and invoking built-in functions significantly aids in application development and the modernization of technology infrastructures. Accessible through Mistral's platform, Azure AI Studio, and Azure Machine Learning, it also provides an option for self-deployment, making it suitable for sensitive applications. Benchmark results indicate that Mistral Large excels in performance, ranking as the second-best model worldwide available through an API, closely following GPT-4, which underscores its strong position within the AI sector. This blend of features and capabilities positions Mistral Large as an essential resource for developers aiming to harness cutting-edge AI technologies effectively. Moreover, its adaptable nature allows it to meet diverse industry needs, further enhancing its appeal as a versatile AI solution.

Mistral AI has unveiled the Mistral Large 2, an advanced AI model engineered to perform exceptionally well across various fields, including code generation, multilingual comprehension, and complex reasoning tasks. Boasting a remarkable 128k context window, this model supports a vast selection of languages such as English, French, Spanish, and Arabic, as well as more than 80 programming languages. Tailored for high-throughput single-node inference, Mistral Large 2 is ideal for applications that demand substantial context management. Its outstanding performance on benchmarks like MMLU, alongside enhanced abilities in code generation and reasoning, ensures both precision and effectiveness in outcomes. Moreover, the model is equipped with improved function calling and retrieval functionalities, which are especially advantageous for intricate business applications. This versatility positions Mistral Large 2 as a formidable asset for developers and enterprises eager to harness cutting-edge AI technologies for innovative solutions, ultimately driving efficiency and productivity in their operations.

Claude Haiku 3 distinguishes itself as the fastest and most economical model in its intelligence class. It features state-of-the-art visual capabilities and performs exceptionally well in multiple industry evaluations, rendering it a versatile option for a wide array of business uses. Presently, users can access the model via the Claude API and at claude.ai, which is offered to Claude Pro subscribers, along with Sonnet and Opus. This innovation significantly expands the resources available to businesses aiming to harness the power of advanced AI technologies. As companies seek to improve their operational efficiency, such solutions become invaluable assets in driving progress.

Claude Opus 4.1 marks a significant iterative improvement over its earlier version, Claude Opus 4, with a focus on enhancing capabilities in coding, agentic reasoning, and data analysis while keeping deployment straightforward. This latest iteration achieves a remarkable coding accuracy of 74.5 percent on the SWE-bench Verified, alongside improved research depth and detailed tracking for agentic search operations. Additionally, GitHub has noted substantial progress in multi-file code refactoring, while Rakuten Group highlights its proficiency in pinpointing precise corrections in large codebases without introducing errors. Independent evaluations show that the performance of junior developers has seen an increase of about one standard deviation relative to Opus 4, indicating meaningful advancements that align with the trajectory of past Claude releases.