List of the Top AI Agent Builders for AG-UI in 2026

The Agent Development Kit (ADK) is a modular, open-source framework that empowers developers to create, test, and deploy AI agents using Google’s cutting-edge technologies. Built for seamless integration with Gemini models, ADK supports the creation of simple, task-oriented agents or complex multi-agent systems capable of sophisticated collaboration and coordination. The platform offers advanced features like dynamic routing, pre-built tools for common tasks, and an ecosystem that supports third-party libraries. With flexible deployment options such as Gemini Enterprise Agent Platform, Cloud Run, or local environments, ADK is a robust solution for building scalable, production-ready AI systems.

LangGraph empowers users to achieve greater accuracy and control by facilitating the development of agents that can adeptly handle complex tasks. It serves as a robust platform for building and scaling applications driven by these intelligent agents. The platform’s versatile structure supports a range of control strategies, such as single-agent, multi-agent, hierarchical, and sequential flows, effectively meeting the demands of complicated real-world scenarios. To ensure dependability, simple integration of moderation and quality loops allows agents to stay aligned with their goals. Moreover, LangGraph provides the tools to create customizable templates for cognitive architecture, enabling straightforward configuration of tools, prompts, and models through LangGraph Platform Assistants. With a built-in stateful design, LangGraph agents collaborate with humans by preparing work for review and waiting for consent before proceeding with actions. Users have the capability to oversee the decision-making processes of the agents, while the "time-travel" function offers the ability to revert and modify prior actions for enhanced accuracy. This adaptability not only ensures effective task execution but also allows agents to respond to evolving needs and constructive feedback, fostering continuous improvement in their performance. As a result, LangGraph stands out as a powerful ally in navigating the complexities of task management and optimization.

Agentivity is a no-code platform aimed at developing AI agents, enabling teamwork, and enhancing workflow efficiency. Users can easily describe a task, prompting the platform’s Assistant to assemble a team of AI specialists for assessment and refinement. Managers are empowered to distribute tasks among these experts, while users can build workflows that seamlessly incorporate AI features alongside existing rules, forms, and approval mechanisms. The agents have the capability to tap into a network of AI models, tools, knowledge bases, and data tables to boost their productivity. Additionally, workflows can be configured to temporarily halt, allowing for human oversight or the gathering of supplementary information before moving forward. Both teams and workflows can be preserved and shared using hosted team plans, fostering collaboration. Agentivity is available as both a hosted service and a self-hosted Community edition, making it suitable for individuals and organizations leveraging AI across various business functions, such as operations, finance, human resources, marketing, and content creation. This versatility not only enhances operational efficiency but also empowers users to maximize their potential with AI-driven solutions, making it a top choice for those eager to improve their workflow dynamics.

PydanticAI is a cutting-edge framework designed in Python, aiming to streamline the development of top-notch applications that harness the power of generative AI technologies. Created by the developers behind Pydantic, this framework easily integrates with major AI models like OpenAI, Anthropic, and Gemini. It employs a type-safe structure that allows for real-time debugging and performance monitoring through the Pydantic Logfire system. By leveraging Pydantic for output validation, PydanticAI ensures that responses from models are both structured and consistent. Furthermore, the framework includes a dependency injection system that supports an iterative approach to development and testing, while also facilitating the streaming of LLM outputs for rapid validation. Ideal for projects centered around AI, PydanticAI encourages a flexible and efficient assembly of agents, all while following best practices in Python development. Ultimately, PydanticAI aspires to deliver a seamless experience akin to FastAPI in the context of generative AI application creation, thus improving the overall workflow for developers significantly. With its robust features and user-friendly design, PydanticAI is set to become an essential tool for those looking to excel in the AI development landscape.

Mastra is an open-source TypeScript framework designed to help software developers build production-ready AI agents, intelligent applications, and autonomous workflow systems. The framework provides a modular development environment for defining AI agents with configurable instructions, language models, tools, memory, and runtime behavior. Its agent execution capabilities allow applications to process user requests, reason about complex problems, select appropriate tools, and perform actions across connected systems. Mastra's workflow engine enables developers to organize operations into structured steps with branching logic, retries, error handling, and persistent execution state. Human-in-the-loop functionality allows workflows to pause for user input or approval and resume execution without losing their previous progress. Its memory system supports conversation history, structured working memory, semantic retrieval, and observational memory that summarizes previous interactions to maintain useful context. The platform also provides an agent harness for coordinating long-running agents with multiple operating modes, shared state, persistent threads, and task management capabilities. Model integration features enable developers to work with different AI providers through a unified router, while Model Context Protocol support connects agents to external tools, resources, and compatible applications. Built-in observability includes distributed tracing, execution logs, latency measurements, token usage monitoring, cost tracking, and detailed visibility into model calls and tool interactions. Its evaluation framework supports automated scoring, test datasets, experiments, feedback collection, and regression testing to help development teams measure and improve agent performance.

Agno is an innovative framework tailored for the development of agents that possess memory, knowledge, tools, and reasoning abilities. It enables developers to create a wide array of agents, including those that reason, operate multimodally, collaborate in teams, and execute complex workflows. With an appealing user interface, Agno not only facilitates seamless interaction with agents but also includes features for monitoring and assessing their performance. Its model-agnostic nature guarantees a uniform interface across over 23 model providers, effectively averting the challenges associated with vendor lock-in. Agents can be instantiated in approximately 2 microseconds on average, which is around 10,000 times faster than LangGraph, while utilizing merely 3.75KiB of memory—50 times less than LangGraph. The framework emphasizes reasoning, allowing agents to engage in "thinking" and "analysis" through various reasoning models, ReasoningTools, or a customized CoT+Tool-use strategy. In addition, Agno's native multimodality enables agents to process a range of inputs and outputs, including text, images, audio, and video. The architecture of Agno supports three distinct operational modes: route, collaborate, and coordinate, which significantly enhances agent interaction flexibility and effectiveness. Overall, by integrating these advanced features, Agno establishes a powerful platform for crafting intelligent agents capable of adapting to a multitude of tasks and environments, promoting innovation in agent-based applications.

LlamaIndex functions as a dynamic "data framework" aimed at facilitating the creation of applications that utilize large language models (LLMs). This platform allows for the seamless integration of semi-structured data from a variety of APIs such as Slack, Salesforce, and Notion. Its user-friendly yet flexible design empowers developers to connect personalized data sources to LLMs, thereby augmenting application functionality with vital data resources. By bridging the gap between diverse data formats—including APIs, PDFs, documents, and SQL databases—you can leverage these resources effectively within your LLM applications. Moreover, it allows for the storage and indexing of data for multiple applications, ensuring smooth integration with downstream vector storage and database solutions. LlamaIndex features a query interface that permits users to submit any data-related prompts, generating responses enriched with valuable insights. Additionally, it supports the connection of unstructured data sources like documents, raw text files, PDFs, videos, and images, and simplifies the inclusion of structured data from sources such as Excel or SQL. The framework further enhances data organization through indices and graphs, making it more user-friendly for LLM interactions. As a result, LlamaIndex significantly improves the user experience and broadens the range of possible applications, transforming how developers interact with data in the context of LLMs. This innovative framework fundamentally changes the landscape of data management for AI-driven applications.

CrewAI distinguishes itself as a leading multi-agent platform that assists enterprises in enhancing workflows across diverse industries by developing and executing automated processes utilizing any Large Language Model (LLM) and cloud technologies. It offers a rich suite of tools, including a robust framework and a user-friendly UI Studio, which facilitate the rapid development of multi-agent automations, catering to both seasoned developers and those who prefer to avoid coding. The platform presents flexible deployment options, allowing users to seamlessly transition their created 'crews'—made up of AI agents—into production settings, supported by sophisticated tools designed for various deployment needs and automatically generated user interfaces. Additionally, CrewAI encompasses thorough monitoring capabilities that enable users to evaluate the effectiveness and advancement of their AI agents in handling both simple and complex tasks. It also provides resources for testing and training, aimed at consistently enhancing the efficiency and quality of the outputs produced by these AI agents. By doing so, CrewAI not only streamlines processes but also enables organizations to fully leverage the transformative power of automation in their daily operations. This comprehensive approach positions CrewAI as a vital asset for any business looking to innovate and improve its operational efficiencies.