What is an AI Agent? The role of AI Agent tools.
An AI agent is intelligent software that can automate repetitive tasks that you previously needed to delegate to humans. AI agent tools typically have a no-code interface, making it easy for anyone to create, deploy, and manage automated processes.

Imagine this: if you could write down every step to complete a task, such as sending an email, entering data, or providing customer service, then an AI agent could do it for you. As long as the task has a clear process, it can be automated.

This is the core strength of AI Agents: reducing manual work time and increasing efficiency without increasing staff.

Therefore, AI Agents are becoming the ideal “digital assistant” for:

• Solopreneur
• Freelancer
• Small teams want to get more done at a lower cost.

An AI agent is intelligent software that can automate repetitive tasks. (Source: TOS)

Criteria for selecting AI Agent building tools

AI is developing rapidly, leading to many tools labeled “AI Agent” that don’t deliver real results. However, recently, several reliable platforms have emerged that are powerful enough for practical deployment. Before choosing the right tool, you should consider the following important criteria:

• Flexible LLM and API integration: The tool should support connections with major AI models like ChatGPT, Claude, Gemini, as well as the software APIs you are already using. This is key to expanding automation capabilities.
• Clear and reasonable costs: Most AI platforms operate on a “credit” model, charging based on the number of API calls or AI model uses. Carefully examine the pricing structure: Which tools require you to connect the API yourself, and which include integration costs?
• Powerful automation capabilities: AI agents need to be able to handle tasks from A to Z without any manual intervention. Some even support running on a recurring or predefined schedule.
• Stable processing speed: For complex tasks, processing speed is a crucial factor. Real-world performance should be tested before official deployment.
• Data security: If you handle sensitive information, choose a tool with a clear privacy policy and one that does not use user data to train its model.
• Community and technical support: A good platform needs clear documentation, prompt technical support, and an active user community so you can learn and troubleshoot easily.

 

Criteria for selecting AI Agent building tools (Source: TOS)

Top 10 Best AI Agent Tools of 2025

AI agents are gradually becoming indispensable tools in automation and workflow optimization. With a multitude of platforms emerging, choosing the right tool is not easy. Below are 10 of the most outstanding AI agent tools in 2025, highly rated for features, price, and practical application.

1. Gumloop

Gumloop is a powerful no-code platform that lets you build automation workflows via a drag-and-drop interface. Think of it as a combination of Zapier and ChatGPT, with the ability to naturally integrate LLM into your workflow. This tool is suitable for marketing teams (SEO, advertising, web scraping).

Key features:

• Nodes: Drag and drop tools, LLM models, and applications into workflows.
• Flows: Building coherent automation processes.
• Subflows: Create reusable, highly flexible subflows.
• There is a rich library of sample processes for beginners.

Price:

• Free: 1,000 credits
• Starter: $97/month – 30,000 credits
• Pro: $297/month – 75,000 credits
• Enterprise: Contact us for a quote.

2. Relay.app

Relay is a simple and intuitive AI Agent tool designed to help small teams automate daily workflows, from customer service to lead management. It’s suitable for agencies, customer service teams, and freelancers.

Key features:

• Integrates many popular applications.
• It’s easy to create agents like: Discord AI bots, CRM data enrichment tools from LinkedIn.
• There’s a library of ideas and practical examples to help you get started.

Price:

• Free: 500 LLM credits
• Pro: $11.25/month – 1,000 credits
• Team: $73.75/month – 2,000 credits, unlimited users.
• Enterprise: Contact us for a quote.

3. HockeyStack

HockeyStack is a premium AI agent platform for B2B marketing teams in large enterprises. Initially focused on revenue analytics, HockeyStack now integrates AI to automate and analyze multi-touchpoint customer journeys.

Key features:

• Integrating internal data to deliver in-depth analysis using AI.
• A powerful multi-touch attribution marketing measurement system.
• Not a self-service platform, suitable for large-scale businesses.
• Personalized demos are available for executive and senior management teams.

Price: From $2,200/month

4. Stack AI

Stack AI is a no-code platform that helps businesses create automation processes and AI agents without programming. It’s suitable for SaaS companies, educational institutions, finance, and healthcare.

Key features:

• Easy-to-use drag-and-drop interface, diverse template library.
• Integrating multiple LLM applications and models.
• Supports complex logic and process reuse.
• Suitable for both technical and non-technical teams.

Price:

• 7-day free trial
• Starter: $199/month – 2,000 views
• Team: $899/month – 5,000 views
• Enterprise: Separate quote

5. Voiceflow

Voiceflow is an AI-powered chatbot and voicebot design platform suitable for customer service teams or businesses looking to enhance their voice and text-based interaction channels.

Key features:

• A visual editor, user-friendly for non-professionals.
• Create an AI agent to support customers across multiple channels.
• Supports building complex, multi-threaded conversations.
• Integrates with LLM to enhance natural responsiveness.

Price:

• Sandbox: Free – 100,000 tokens/month
• Pro: $50/month – 4 million tokens
• Team: $125/month – 20 million tokens
• Enterprise: Separate quote

6. OpenAI’s Operator

Operator is an AI Agent platform developed by OpenAI itself, allowing you to automate web tasks like a human, even on websites without APIs.

Key features:

• It’s possible to interact with any website just like a real person.
• Suitable for performing personal tasks: booking tickets, filling out forms, etc.
• Leverage OpenAI’s powerful LLM for natural language processing.
• It’s still in beta but has huge potential.

Price:

• From $199/month
• There aren’t many official reviews yet (but there’s positive discussion on Reddit).

7. Become AI

Devin AI is an AI programming assistant that helps developers write code, build software, and automate engineering processes. It’s often described as an “AI colleague” within the development team.

Key features:

• It is possible to set up the environment, write code, run tests, and debug.
• Integrates a separate shell, browser, and code editor.
• Perform tasks independently, just like a junior software engineer.
• Suitable for individuals or development teams looking to accelerate development.

Price:

• From $500/month
• Reviews are still limited, but it has received significant attention from the developer community on X (Twitter).

8. AirOps

AirOps is an AI agent building platform specifically designed for SEO and content growth teams. It’s an ideal tool for agencies, large businesses, or professionals working in content marketing.

Key features:

• AI Agent design supports SEO and content optimization on a large scale.
• AirOps Academy provides detailed instructions on how to use and apply it in practice.
• Suitable for teams that need to manage multiple SEO campaigns simultaneously.
• Easy to integrate into existing marketing processes.

Price:

• Solo (Free): 1,000 credits
• Solo (Paid): $199/month – 10,000 credits
• Scale / Agency: Customizable pricing, suitable for large organizations.

9. Zep

Zep is a platform for AI Agent developers, providing “extension blocks” to integrate complex memorization and processing capabilities into applications. It’s a suitable choice for large enterprises or AI products at production scale.

Key features:

• Not a no-code platform, requires technical knowledge.
• Enhance the memory and contextual capabilities of existing AI agents.
• Optimized for building custom, scalable AI Agent systems.
• Used by large organizations such as WebMD, Athena

Price:

• Free: 2,000 messages/month
• Team: $99/month – 75,000 messages
• Growth: $640/month – 500,000 messages
• Enterprise: Contact us for a quote.

10. Postman

Postman is a popular API platform that has now expanded its capabilities to include building and testing AI agents. It’s suitable for software engineers, especially those building complex AI systems based on APIs and LLMs.

Key features:

• Design, test, and monitor AI agents via API.
• Support for testing interaction with LLM
• There’s a visual builder to simplify the process, even for those with little coding experience.
• Suitable for developing large-scale custom AI applications.

Price:

• Free: 25 collectible runs
• Basic: $19/user/month – 10,000 monitoring requests
• Professional: $39/user/month – 25 packages
• Enterprise: Customizable pricing

Conclude

AI agents are no longer a foreign concept; they are gradually becoming powerful assistants in daily work. Whether you are a marketer, programmer, or a business looking to optimize processes, choosing the right AI agent tool is a strategic step. Hopefully, the list of top AI agents and tools for building AI agents in this article will help you begin your journey of applying AI more effectively and practically.

Source:

• https://www.marketermilk.com/blog/best-ai-agent-platforms
• https://www.datacamp.com/blog/best-ai-agents

Note from TOS: The information in this article is compiled from sources that TOS researched at the time of writing. If any updates or corrections are needed, TOS would appreciate your feedback via email.