Best AI Reasoning Models for OpenRouter

GPT-5.6 Sol is OpenAI’s flagship model in the GPT-5.6 series, built for high-end reasoning, coding, scientific analysis, cybersecurity, and agentic automation. The model is designed to handle complex tasks that require planning, iteration, tool coordination, long-horizon reasoning, and careful execution across multiple steps. GPT-5.6 Sol introduces max reasoning effort, giving the model more time to reason deeply through difficult problems. It also introduces ultra mode, which uses subagents to accelerate complex work and extend capability beyond a single-agent workflow. For coding, GPT-5.6 Sol is positioned for command-line workflows, software engineering tasks, debugging, testing, and multi-step tool use. In biology and quantitative research workflows, the model is designed to support genomics analysis and other long-context scientific tasks while using tokens more efficiently than prior models. For cybersecurity, GPT-5.6 Sol supports legitimate defensive work such as vulnerability research, code review, patch development, security education, and defensive testing. The model includes a layered safeguard stack with trained refusals, real-time cyber and biology misuse classifiers, account-level monitoring, differentiated access, human-in-the-loop review, and ongoing red-team testing. GPT-5.6 Sol helps trusted users and organizations access more powerful AI for technical work while maintaining stronger controls around misuse, sensitive requests, and high-risk activity.

GPT-5.6 Terra is OpenAI’s balanced GPT-5.6 model for users who need strong performance across everyday work, development tasks, enterprise workflows, and technical analysis. The model is part of the GPT-5.6 family alongside Sol and Luna, with Terra positioned as the middle tier for capable, cost-efficient use. Terra is described as having competitive performance to GPT-5.5 while being 2x cheaper, making it useful for teams that want advanced capability without always using the flagship model. It supports coding workflows, agentic tasks, cybersecurity-related defensive work, biology workflows, knowledge work, and tool-assisted automation. In benchmark previews, Terra appears alongside Sol and Luna in evaluations for coding, biology, ExploitBench, and ExploitGym. The model benefits from the GPT-5.6 safeguard stack, which includes model-level refusals for prohibited cyber assistance, real-time cyber and biology misuse classifiers, and account-level risk review. These safeguards are designed to preserve access to legitimate work such as code review, debugging, vulnerability research, patch development, security education, and defensive testing. GPT-5.6 Terra is planned for availability through the API, Codex, and broader OpenAI products after the limited preview period. GPT-5.6 Terra helps teams get a balanced model for high-quality AI work when they need strong reasoning and automation at a lower cost than Sol.

GPT-5.6 Luna is OpenAI’s fast, cost-efficient model in the GPT-5.6 lineup. The GPT-5.6 family includes Sol for flagship performance, Terra for balanced everyday work, and Luna for strong capability at the lowest listed price. Luna is designed for users who need scalable AI support for routine tasks, coding assistance, workflow automation, analysis, and production API use cases where speed and cost matter. According to the pasted preview text, Luna is priced below both Sol and Terra, making it the most affordable GPT-5.6 option for high-volume workloads. The model is included in GPT-5.6 benchmark previews across Terminal-Bench 2.1, GeneBench v1, ExploitBench, and ExploitGym, showing that it is part of the same technical family used for coding, biology, and cybersecurity evaluations. Luna benefits from safeguards developed across the GPT-5.6 series, including model-level refusal training, real-time cyber and biology misuse classifiers, account-level signals, differentiated access, monitoring, enforcement, and ongoing testing. These controls are designed to preserve legitimate use cases such as debugging, code review, defensive testing, security education, and productivity automation while constraining prohibited misuse. GPT-5.6 Luna is planned for broader access through ChatGPT, Codex, and the API after the limited preview period. GPT-5.6 Luna helps developers and organizations run useful AI workflows with a practical balance of affordability, responsiveness, and safety.

GLM-5.2 is a next-generation large language model built for users who need strong reasoning, coding support, and agentic AI capabilities. It can assist with complex software development tasks, technical problem-solving, automation workflows, and advanced research projects. The model is designed to process long-context information, which makes it helpful for analyzing large documents, reviewing codebases, and maintaining continuity across multi-step tasks. GLM-5.2 supports developers and organizations that want to create AI-powered tools capable of planning, reasoning, and executing more sophisticated workflows. Its architecture is structured to deliver high performance while improving efficiency for demanding AI use cases. Businesses can use GLM-5.2 to enhance productivity, streamline engineering processes, and build more capable intelligent applications. It is also useful for teams that need AI assistance across documentation, data interpretation, coding, testing, and workflow automation. The model’s emphasis on agentic engineering makes it well-suited for applications that require more than simple text generation. GLM-5.2 provides a flexible AI foundation for companies looking to bring advanced reasoning and automation into their products or internal operations.

GLM-5.3 is Z.ai’s advanced coding and agentic reasoning model built through scaled post-training on top of the GLM-5.2 base model. The release focuses on frontier coding, long-horizon software engineering, agent tasks, cyber evaluation, and reinforcement learning at scale. GLM-5.3 improves significantly over GLM-5.2 on complex coding benchmarks, real-world engineering environments, Terminal Bench 3.0, DeepSWE, Agents’ Last Exam, and Z.ai’s internal Code Bench. The model is trained on environments that resemble real professional work, including tasks involving codebases, infrastructure, documentation, compute clusters, experiments, bottleneck diagnosis, implementation, testing, and measurable optimization. Z.ai’s post-training stack includes IndexShare for efficient long-context processing, SAO for reinforcement learning on long-horizon tasks, and slime for large-scale asynchronous training. GLM-5.3 supports three thinking effort levels, including low, high, and max, with max recommended for coding tasks. The model also demonstrates emergent cyber capabilities across vulnerability discovery and exploitation benchmarks, prompting continued safety evaluation and hardening before weights are released. GLM-5.3 can be used through the GLM Coding Plan, ZCode, Claude Code, OpenCode, and other coding agent workflows. By combining stronger coding performance, long-horizon task execution, post-training scale, cyber evaluation, reasoning effort controls, and coding-agent integrations, GLM-5.3 supports advanced developer and research workflows.

GPT-5.5 is a next-generation AI system built for execution-heavy workflows across coding, research, business analysis, and scientific tasks. It can interpret complex instructions, break them into actionable steps, and carry them through to completion while interacting with tools and systems. The model supports creating applications, generating reports, analyzing datasets, and navigating software environments seamlessly. It also integrates with workspace agents—custom AI agents that automate recurring and multi-step processes across teams. These agents can handle tasks such as lead research, reporting, and workflow automation, either on demand or on schedules. GPT-5.5 enhances productivity by reducing manual effort and enabling continuous task execution across tools. With enterprise-grade safeguards and monitoring, it ensures secure and controlled automation. It is well-suited for organizations looking to scale operations and improve efficiency through AI-driven workflows.

Seed2.1 represents a groundbreaking advancement in productivity tools, featuring two distinct AI models, Pro and Turbo, tailored for varying levels of user needs. Designed to address intricate challenges encountered in everyday tasks, workplace responsibilities, and innovative ventures, this agent significantly enhances capabilities in areas such as general assistance, code development, multimodal comprehension, knowledge application, and reasoning processes. For demanding office tasks and intricate daily consultations, Seed2.1 adeptly manages a range of multi-step processes, including project management, document handling, tool utilization, data analysis, solution formulation, content organization, and synthesis of outcomes. In the realm of software development, Seed2.1 optimizes end-to-end processes within enterprise-level workflows, covering aspects like requirement gathering, software architecture, feature development, debugging, environment configuration, and quality assurance. Additionally, the model is proficient in comprehending entire codebases, effectively coordinating updates across numerous files, and ensuring the delivery of sustainable, production-ready software engineering solutions. Ultimately, Seed2.1 not only enhances productivity but also empowers users to tackle complex challenges with confidence.

Claude Sonnet 3.5 sets a new standard for AI performance with outstanding benchmarks in graduate-level reasoning (GPQA), undergraduate-level knowledge (MMLU), and coding proficiency (HumanEval). This model shows significant improvements in understanding nuance, humor, and complex instructions, while consistently producing high-quality content that resonates naturally with users. Operating at twice the speed of Claude Opus 3, it delivers faster and more efficient results, making it perfect for use cases such as context-sensitive customer support and multi-step workflow automation.

Claude Sonnet 3.7, a state-of-the-art AI model by Anthropic, is designed for versatility, offering users the option to switch between quick, efficient responses and deeper, more reflective answers. This dynamic model shines in complex problem-solving scenarios, where high-level reasoning and nuanced understanding are crucial. By allowing Claude to pause for self-reflection before answering, Sonnet 3.7 excels in tasks that demand deep analysis, such as coding, natural language processing, and critical thinking applications. Its flexibility makes it an invaluable tool for professionals and organizations looking for an adaptable AI that delivers both speed and thoughtful insights.

Google AI Plus is a premium AI subscription plan from Google that gives users expanded access to Gemini-powered productivity, creativity, research, and automation tools across Google’s ecosystem. The subscription includes higher usage limits for the Gemini app along with access to advanced features such as video generation, Daily Brief, AI-powered research tools, and enhanced creative workflows powered by Google’s latest AI models. Users gain access to Google Flow, an AI creative studio that allows them to generate cinematic scenes, stories, and visual content using Gemini Omni Flash and customizable AI tools. The plan also integrates Gemini directly into Google applications including Gmail, Docs, Vids, and Chrome, helping users streamline writing, organization, brainstorming, browsing, and productivity tasks across everyday workflows. Google AI Plus includes enhanced NotebookLM functionality that provides advanced research assistance, audio overviews, notebook management, and writing support powered by AI. Subscribers additionally receive 200 GB of cloud storage across Google Drive, Gmail, and Google Photos, allowing users to store and manage files, media, and AI-generated content in one connected environment. The subscription is designed for individuals seeking more powerful AI-assisted experiences for creative projects, research, productivity, communication, and digital organization without requiring enterprise-level tools or infrastructure. Google AI Plus also provides increased access to AI-powered search capabilities and experimental features that continue expanding as Google introduces new Gemini technologies and AI services.

xAI’s Grok 4 represents a major step forward in AI technology, delivering advanced reasoning, multimodal understanding, and improved natural language capabilities. Built on the powerful Colossus supercomputer, Grok 4 can process text and images, with video input support expected soon, enhancing its ability to interpret cultural and contextual content such as memes. It has outperformed many competitors in benchmark tests for scientific and visual reasoning, establishing itself as a top-tier model. Focused on technical users, researchers, and developers, Grok 4 is tailored to meet the demands of advanced AI applications. xAI has strengthened moderation systems to prevent inappropriate outputs and promote ethical AI use. This release signals xAI’s commitment to innovation and responsible AI deployment. Grok 4 sets a new standard in AI performance and versatility. It is poised to support cutting-edge research and complex problem-solving across various fields.

Grok 4.1 Fast represents xAI’s leap forward in building highly capable agents that rely heavily on tool calling, long-context reasoning, and real-time information retrieval. It supports a robust 2-million-token window, enabling long-form planning, deep research, and multi-step workflows without degradation. Through extensive RL training and exposure to diverse tool ecosystems, the model performs exceptionally well on demanding benchmarks like τ²-bench Telecom. When paired with the Agent Tools API, it can autonomously browse the web, search X posts, execute Python code, and retrieve documents, eliminating the need for developers to manage external infrastructure. It is engineered to maintain intelligence across multi-turn conversations, making it ideal for enterprise tasks that require continuous context. Its benchmark accuracy on tool-calling and function-calling tasks clearly surpasses competing models in speed, cost, and reliability. Developers can leverage these strengths to build agents that automate customer support, perform real-time analysis, and execute complex domain-specific tasks. With its performance, low pricing, and availability on platforms like OpenRouter, Grok 4.1 Fast stands out as a production-ready solution for next-generation AI systems.

GPT-5.1 Pro is a premium, research-focused model tier built for users who need the strongest reasoning performance ChatGPT offers. It excels in technical domains such as advanced mathematics, scientific analysis, engineering, complex coding, and financial modeling. The model is engineered to deliver more coherent long-form reasoning, better chain-of-thought structure, and stronger factual grounding than general-purpose versions. With expanded context capacity, GPT-5.1 Pro handles large documents, multi-file analysis, and intricate workflows with ease. It also produces clearer explanations with reduced jargon, making complex insights more accessible without losing technical depth. Designed for demanding professional environments, Pro adheres to strict accuracy expectations while minimizing hallucinations in critical tasks. It is restricted to ChatGPT Pro and Business plans, ensuring dedicated access with no usage caps beyond standard abuse guardrails. Compared to other tiers, GPT-5.1 Pro is purpose-built for users who rely on ChatGPT as a high-precision analytical engine.

Grok 4.3 is an advanced AI model developed by xAI to provide enhanced reasoning, real-time insights, and automation capabilities. It builds on the Grok 4 architecture, which already includes features like real-time web browsing, multimodal processing, and tool integration. The model is designed to handle complex tasks such as coding, research, and data analysis with improved accuracy and efficiency. Grok 4.3 is integrated with live data sources, including the web and X, allowing it to deliver timely and relevant information. It operates within the SuperGrok Heavy subscription tier, which provides access to its most powerful capabilities. The model supports long-context understanding, enabling it to process large amounts of information in a single session. It also includes multi-agent or “heavy” configurations that enhance problem-solving performance. Grok 4.3 is optimized for speed and responsiveness, making it suitable for real-time applications. It can generate content, answer questions, and assist with workflows across various domains. The platform continues to evolve with new features and improvements aimed at increasing reliability and performance. Overall, Grok 4.3 offers a powerful AI solution for users who need real-time, high-level intelligence and automation.

GLM-5 is a next-generation open-source foundation model from Z.ai designed to push the boundaries of agentic engineering and complex task execution. Compared to earlier versions, it significantly expands parameter count and training data, while introducing DeepSeek Sparse Attention to optimize inference efficiency. The model leverages a novel asynchronous reinforcement learning framework called slime, which enhances training throughput and enables more effective post-training alignment. GLM-5 delivers leading performance among open-source models in reasoning, coding, and general agent benchmarks, with strong results on SWE-bench, BrowseComp, and Vending Bench 2. Its ability to manage long-horizon simulations highlights advanced planning, resource allocation, and operational decision-making skills. Beyond benchmark performance, GLM-5 supports real-world productivity by generating fully formatted documents such as .docx, .pdf, and .xlsx files. It integrates with coding agents like Claude Code and OpenClaw, enabling cross-application automation and collaborative agent workflows. Developers can access GLM-5 via Z.ai’s API, deploy it locally with frameworks like vLLM or SGLang, or use it through an interactive GUI environment. The model is released under the MIT License, encouraging broad experimentation and adoption. Overall, GLM-5 represents a major step toward practical, work-oriented AI systems that move beyond chat into full task execution.

GLM-5.1 represents the latest advancement in Z.ai’s GLM series, crafted as a cutting-edge, agent-focused AI model tailored for coding, reasoning, and managing long-term workflows. This iteration builds upon the framework of GLM-5, which employs a Mixture-of-Experts (MoE) architecture to achieve high performance without incurring excessive inference expenses, aligning with a larger initiative towards open-weight models that are accessible to developers. A significant emphasis of GLM-5.1 is on fostering agentic behavior, allowing it to plan, execute, and refine multi-step tasks instead of merely reacting to isolated prompts. Its capabilities are specifically engineered to manage intricate workflows, such as debugging code, exploring repositories, and performing sequential operations while maintaining context over time. In comparison to its predecessors, GLM-5.1 enhances reliability during lengthy interactions, ensuring coherence throughout extended sessions and minimizing failures in multi-step reasoning processes. Overall, this model signifies a leap forward in AI development, particularly in its ability to support complex task management seamlessly.

Llama 4 Behemoth, with 288 billion active parameters, is Meta's flagship AI model, setting new standards for multimodal performance. Outpacing its predecessors like GPT-4.5 and Claude Sonnet 3.7, it leads the field in STEM benchmarks, offering cutting-edge results in tasks such as problem-solving and reasoning. Designed as the teacher model for the Llama 4 series, Behemoth drives significant improvements in model quality and efficiency through distillation. Although still in development, Llama 4 Behemoth is shaping the future of AI with its unparalleled intelligence, particularly in math, image, and multilingual tasks.

Llama 4 Maverick is a cutting-edge multimodal AI model with 17 billion active parameters and 128 experts, setting a new standard for efficiency and performance. It excels in diverse domains, outperforming other models such as GPT-4o and Gemini 2.0 Flash in coding, reasoning, and image-related tasks. Llama 4 Maverick integrates both text and image processing seamlessly, offering enhanced capabilities for complex tasks such as visual question answering, content generation, and problem-solving. The model’s performance-to-cost ratio makes it an ideal choice for businesses looking to integrate powerful AI into their operations without the hefty resource demands.

Llama 4 Scout is an advanced multimodal AI model with 17 billion active parameters, offering industry-leading performance with a 10 million token context length. This enables it to handle complex tasks like multi-document summarization and detailed code reasoning with impressive accuracy. Scout surpasses previous Llama models in both text and image understanding, making it an excellent choice for applications that require a combination of language processing and image analysis. Its powerful capabilities in long-context tasks and image-grounding applications set it apart from other models in its class, providing superior results for a wide range of industries.

GLM-4.6 builds upon the foundations laid by its predecessor, showcasing enhanced reasoning, coding, and agent capabilities, resulting in notable advancements in inferential accuracy, improved tool usage during reasoning tasks, and a more seamless integration within agent frameworks. In comprehensive benchmark evaluations that assess reasoning, coding, and agent performance, GLM-4.6 surpasses GLM-4.5 and competes robustly against other models like DeepSeek-V3.2-Exp and Claude Sonnet 4, although it still lags behind Claude Sonnet 4.5 in terms of coding capabilities. Furthermore, when subjected to practical tests utilizing an extensive “CC-Bench” suite that includes tasks in front-end development, tool creation, data analysis, and algorithmic challenges, GLM-4.6 outperforms GLM-4.5 while nearing parity with Claude Sonnet 4, achieving victory in approximately 48.6% of direct comparisons and demonstrating around 15% improved token efficiency. This latest model is accessible through the Z.ai API, providing developers the flexibility to implement it as either an LLM backend or as the core of an agent within the platform's API ecosystem. In addition, its advancements could significantly enhance productivity in various application domains, making it an attractive option for developers looking to leverage cutting-edge AI technology.

The GLM-4.6V is an advanced, open-source multimodal vision-language model that belongs to the Z.ai (GLM-V) family, specifically engineered for tasks involving reasoning, perception, and action. It is available in two configurations: a comprehensive version with 106 billion parameters suitable for cloud environments or high-performance computing clusters, and a streamlined “Flash” variant featuring 9 billion parameters, which is tailored for local implementation or scenarios requiring low latency. With a remarkable native context window that accommodates up to 128,000 tokens during its training phase, GLM-4.6V can effectively manage extensive documents or multimodal data inputs. One of its standout features is the built-in Function Calling capability, allowing the model to accept various forms of visual media — such as images, screenshots, and documents — as inputs directly, eliminating the need for manual text conversion. This functionality not only facilitates reasoning about the visual content but also enables the model to initiate tool calls, effectively merging visual perception with actionable results. The versatility of GLM-4.6V opens the door to a wide array of applications, including the generation of interleaved image-and-text content, which can seamlessly integrate document comprehension with text summarization or the creation of responses that include image annotations, thereby greatly enhancing user interaction and output quality.

GLM-4.1V is an advanced vision-language model that offers a robust and streamlined multimodal capability for reasoning and understanding across various forms of media, including images, text, and documents. The 9-billion-parameter version, known as GLM-4.1V-9B-Thinking, is developed on the foundation of GLM-4-9B and has been improved through a unique training approach that employs Reinforcement Learning with Curriculum Sampling (RLCS). This model accommodates a context window of 64k tokens and can process high-resolution inputs, supporting images up to 4K resolution with any aspect ratio, which allows it to tackle intricate tasks such as optical character recognition, image captioning, chart and document parsing, video analysis, scene comprehension, and GUI-agent workflows, including the interpretation of screenshots and recognition of UI elements. In benchmark tests conducted at the 10 B-parameter scale, GLM-4.1V-9B-Thinking demonstrated exceptional capabilities, achieving the highest performance on 23 out of 28 evaluated tasks. Its advancements signify a substantial leap forward in the integration of visual and textual data, setting a new standard for multimodal models in various applications.

GLM-4.5V-Flash is a vision-language model that is open source and specifically crafted to integrate robust multimodal functionalities into a compact and easily deployable framework. It accommodates various types of inputs including images, videos, documents, and graphical user interfaces, facilitating a range of tasks such as understanding scenes, parsing charts and documents, reading screens, and analyzing multiple images. In contrast to its larger counterparts, GLM-4.5V-Flash maintains a smaller footprint while still embodying essential visual language model features such as visual reasoning, video comprehension, handling GUI tasks, and parsing complex documents. This model can be utilized within “GUI agent” workflows, allowing it to interpret screenshots or desktop captures, identify icons or UI components, and assist with both automated desktop and web tasks. While it may not achieve the performance enhancements seen in the largest models, GLM-4.5V-Flash is highly adaptable for practical multimodal applications where efficiency, reduced resource requirements, and extensive modality support are key considerations. Its design ensures that users can harness powerful functionalities without sacrificing speed or accessibility.

GLM-4.5V is an evolution of the GLM-4.5-Air model, incorporating a Mixture-of-Experts (MoE) framework that boasts a remarkable total of 106 billion parameters, with 12 billion specifically dedicated to activation. This model stands out by delivering top-tier performance among open-source vision-language models (VLMs) of comparable scale, demonstrating exceptional capabilities across 42 public benchmarks in diverse contexts such as images, videos, documents, and GUI interactions. It offers an extensive array of multimodal functionalities, encompassing image reasoning tasks like scene understanding, spatial recognition, and multi-image analysis, alongside video comprehension tasks that include segmentation and event recognition. Furthermore, it excels in parsing complex charts and lengthy documents, facilitating GUI-agent workflows through tasks like screen reading and desktop automation, while also providing accurate visual grounding by locating objects and generating bounding boxes. Additionally, the introduction of a "Thinking Mode" switch enhances user experience by allowing the selection of either rapid responses or more thoughtful reasoning based on the situation at hand. This innovative feature makes GLM-4.5V not only versatile but also adaptable to various user needs.

GLM-4.7 is a next-generation AI model built to serve as a powerful coding and reasoning partner. It improves significantly on its predecessor across software engineering, multilingual coding, and terminal interaction benchmarks. GLM-4.7 introduces enhanced agentic behavior by thinking before tool use or execution, improving reliability in long and complex tasks. The model demonstrates strong performance in real-world coding environments and popular coding agents. GLM-4.7 also advances visual and frontend generation, producing modern UI designs and well-structured presentation slides. Its improved tool-use capabilities allow it to browse, analyze, and interact with external systems more effectively. Mathematical and logical reasoning have been strengthened through higher benchmark performance on challenging exams. The model supports flexible reasoning modes, allowing users to trade latency for accuracy. GLM-4.7 can be accessed via Z.ai, OpenRouter, and agent-based coding tools. It is designed for developers who need high performance without excessive cost.