Fortress
Run AI agents safely in an isolated sandbox environment.
Quick answer
Fortress — Run AI agents safely in an isolated sandbox environment. It's free. Best for testing AI agent workflows in a safe, isolated environment before production deployment.
Fortress is a free, open-source sandboxed execution and browser environment specifically designed for running AI agents in a controlled and isolated setting. It provides developers and AI engineers with a secure runtime where autonomous agents can execute code, interact with web browsers, and perform tasks without posing risks to the host system or broader infrastructure. This makes Fortress particularly valuable for teams building, testing, or deploying AI agent workflows who need strict security boundaries between the agent and the underlying environment. Unlike general-purpose containerization tools, Fortress is purpose-built for the unique demands of AI agent execution, offering browser automation support alongside code sandboxing in a single cohesive package. Developers experimenting with large language model agents, autonomous workflows, or multi-step AI pipelines will find Fortress a practical foundation for safe experimentation and production hardening.
Key features
- Sandboxed code execution environment to isolate AI agent runtime from the host system
- Integrated browser environment for agent-driven web interaction and automation
- Open-source codebase allowing full customization and self-hosting
- Designed specifically for safe deployment of autonomous AI agents
Pros & cons
- +Completely free and open-source with no licensing costs
- +Purpose-built for AI agent safety rather than a generic sandbox
- +Combines code execution and browser automation in one tool
- −Early-stage project with limited community documentation compared to mature alternatives
- −Requires self-hosting and technical setup, which may not suit non-developer users
Pricing
Fully free and open-source
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Who is it for
- →Testing AI agent workflows in a safe, isolated environment before production deployment
- →Building autonomous browser automation pipelines with built-in security boundaries
- →Developing and debugging LLM-powered agents without risking host system integrity
Frequently asked questions
Is Fortress free?
Yes, Fortress is completely free and open-source. It is hosted on GitHub and available to anyone at no cost under an open-source license.
What is Fortress best used for?
Fortress is best used for safely running AI agents, including autonomous code execution and browser automation, in a sandboxed environment that protects the host system from unintended agent actions.
What are the best alternatives to Fortress?
Alternatives include E2B, Modal, Daytona, and Docker-based custom sandboxes. Each offers varying degrees of AI agent support, browser automation, and managed versus self-hosted options.
Is Fortress safe to use?
Fortress is designed with safety as its core purpose. By isolating agent execution in a sandbox, it prevents agents from directly affecting the host system. However, as with any open-source tool, users should review the code and apply their own security best practices.
How much does Fortress cost?
Fortress costs nothing. It is a free, open-source project available on GitHub, and there are no paid plans, subscriptions, or enterprise tiers at this time.
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