Free plans compared
Best Free Open-Source AI Agent Frameworks (2026)
Open-source agent frameworks let developers build assistants and workflows that call models and tools. The software is free, but model usage and hosting are not. This guide lists frameworks and builders we have reviewed, with the free or self-hosted limits noted.
Disclosure: some Visit links may be affiliate links, and we may earn a commission at no extra cost to you. Details come from official pricing and product pages, last reviewed 2026-10-15; this is not a hands-on test. Confirm current limits with the provider.
What to check before you choose
- Is it a code library or a visual builder?
- Which model providers and tools does it support?
- What are the licence terms for commercial use?
- How do you observe, test and limit what the agent does?
How we chose: tools listed here have an active product, a free plan or free tier, and pricing we could confirm from the provider. Retired or paid-only tools are left out automatically.
Quick comparison of free plans
| Tool | Free plan | No card needed | Platforms |
|---|---|---|---|
| Browser Use | The open-source framework is free; hosted services are paid. | — | API, Web |
| CrewAI | The free Basic plan includes the visual editor, AI copilot and GitHub integration, with 50 workflow executions per month. | — | Web |
| Agno | The open-source runtime and a local control-plane option are free; paid plans add live connections, seats and enterprise controls. | — | Web, API |
| Langflow | The framework is open source. Deployment, model providers, retrieval services, and hosted support can create separate costs. | — | Not recorded |
| Flowise | The open-source edition can be self-hosted, while hosted and enterprise access have separate terms. | — | Web, API |
| Dify | Cloud Sandbox is free: 1 team member, 5 apps, 200 message credits (the page gives no renewal period), 50 knowledge documents and 50 MB storage. | — | Web |
| Letta | The continuing Free option has limited stateful agents and model usage, with supported bring-your-own-key or external coding-plan connections. | — | Web, API |
| Mastra | 0 open-source software, and the hosted platform has a limited recurring Starter option. | — | Web, API |
| Pydantic AI | The Python SDK is open source and free to use. Model APIs, compute and optional hosted services such as observability or gateways have separate terms and costs. | — | API |
| LlamaIndex | LlamaParse has recurring free monthly credits and paid usage tiers. | — | Web, API |
| Haystack | The open-source framework can be used without a software subscription; enterprise platform and support access are paid. | — | Web, API |
| AutoGPT | No permanent free hosted plan: eligible new accounts get a 7-day Pro trial (card required, no charge at signup). | — | Web |
The tools, in detail
Browser Use provides an open-source browser-agent framework and hosted browser services.
Best for: AI browser agents for controlled web tasks
Free plan: The open-source framework is free; hosted services are paid. Cloud pricing lists model cost plus a 20% fee, browser time and traffic; bring-your-own keys still have service charges.
Key features
- Browser-agent framework
- Hosted browsers
- Model connections
- Python integration
Limits to know
- Page changes and authentication can interrupt an agent
- Model use, hosted browser time and traffic can all contribute to cost
Agent build-and-run platform and developer framework for coordinating AI workflows with enterprise deployment options.
Best for: Agent coordination and Workflow orchestration
Free plan: The free Basic plan includes the visual editor, AI copilot and GitHub integration, with 50 workflow executions per month. Enterprise is custom-priced with SSO, RBAC, VPC/own-infrastructure deployment and additional executions. Model and infrastructure costs are separate.
Key features
- Agent coordination
- Workflow orchestration
- Developer framework
- Enterprise runtime
Limits to know
- Framework, Free, and Enterprise offerings have different access. Model and infrastructure costs are separate; enterprise deployment and governance require provider arrangements.
Build and run agents, teams, and workflows with memory, knowledge, evaluations, and an AgentOS control plane.
Best for: Agno suits developers assembling an agent platform on infrastructure they operate.
Free plan: The open-source runtime and a local control-plane option are free; paid plans add live connections, seats and enterprise controls. Hosting, models, storage and connected services remain your responsibility. Check the distinction between a local free connection and a live managed control plane.
Key features
- Agent and team building
- Structured workflows
- Memory and knowledge tools
- Agent evaluations
Limits to know
- The team must operate the application infrastructure
- Live control-plane connections and team controls are plan-dependent
Visual Python framework for building, testing, and serving AI agents and retrieval workflows with reusable components.
Best for: Python developers building visual agent and retrieval workflows
Free plan: The framework is open source. Deployment, model providers, retrieval services, and hosted support can create separate costs.
Key features
- Visual flow builder
- Agent and MCP support
- Custom Python components
- Flow testing
Build AI agents and retrieval workflows visually, with tool connections, human review steps, traces, and APIs.
Best for: Flowise suits developers assembling model, retrieval and tool components without writing every orchestration step from scratch.
Free plan: The open-source edition can be self-hosted, while hosted and enterprise access have separate terms. Free software does not include model inference, vector storage or infrastructure. Check the current license and feature boundaries, including team controls and enterprise components, before deploying a production service.
Key features
- Visual agent builder
- Retrieval workflows
- Human-in-the-loop steps
- Execution traces
Limits to know
- Production deployment requires operational work
- Models, storage and hosting can create separate charges
AI app and workflow platform with model connections, knowledge pipelines, tools, and cloud or self-hosted deployment.
Best for: Workflow studio and Knowledge pipelines
Free plan: Cloud Sandbox is free: 1 team member, 5 apps, 200 message credits (the page gives no renewal period), 50 knowledge documents and 50 MB storage. Community self-hosting is free and open source via Docker, single workspace, and needs your own infrastructure and model access.
Key features
- Workflow studio
- Knowledge pipelines
- Model integrations
- Tool marketplace
Limits to know
- Cloud Sandbox is free with limited trial message credits. Community self-hosting has licence conditions and requires infrastructure and model access.
Build stateful AI agents that retain memory across sessions, with a web app, CLI workflow, and developer API.
Best for: Letta suits builders who need an agent to maintain context beyond one conversation.
Free plan: The continuing Free option has limited stateful agents and model usage, with supported bring-your-own-key or external coding-plan connections. Pro and developer API access have separate quotas or usage billing. Model tokens and server-side tools can add charges.
Key features
- Stateful agents
- Persistent agent memory
- Web and CLI workflows
- Tool connections
Limits to know
- Free agents and hosted usage are limited
- External models and tool execution can add separate charges
A TypeScript framework for agents, tools, workflows, memory, and evaluation, with a hosted platform option.
Best for: Mastra suits TypeScript developers building a repeatable agent application.
Free plan: The core framework is Apache-2.0 open-source software, and the hosted platform has a limited recurring Starter option. Paid platform and enterprise features add allowances or controls. Model tokens, storage and compute can cost extra even when framework access is free.
Key features
- TypeScript agents and tools
- Structured workflows
- Agent memory
- Studio development interface
Limits to know
- The application still needs model and infrastructure configuration
- Hosted free quotas do not include unrestricted production resources
A Python AI SDK for typed agent outputs, model connections, tool calls, dependency injection, and evaluation workflows.
Best for: Pydantic AI suits Python developers building agents inside an application with explicit input and output contracts.
Free plan: The Python SDK is open source and free to use. Model APIs, compute and optional hosted services such as observability or gateways have separate terms and costs. Check the chosen provider and current package documentation; installing a free SDK does not include a hosted model allowance.
Key features
- Typed agent outputs
- Model-provider connections
- Tool calling
- Dependency injection
Limits to know
- Developers must build and operate the application
- Schema validity does not establish factual correctness
Document-AI tools for parsing, structured extraction, indexing, and building source-based agent workflows.
Best for: LlamaIndex suits developers turning documents into usable context or structured records.
Free plan: LlamaParse has recurring free monthly credits and paid usage tiers. It is a commercial service, separate from the open-source framework. Parsing modes and extraction consume credits; applications may also incur model, database and hosting charges.
Key features
- Layout-aware document parsing
- Schema-based extraction
- Document indexing
- Document agent workflows
Limits to know
- Managed parsing is credit-limited and not open source
- Framework applications still need models and infrastructure
An open-source Python framework for retrieval pipelines, document indexing, and tool-using AI agents.
Best for: Haystack suits developers assembling a document-grounded application from explicit components.
Free plan: The open-source framework can be used without a software subscription; enterprise platform and support access are paid. Self-hosted deployment still needs storage, compute and possibly paid models. No free hosted inference is implied by the framework license.
Key features
- Document indexing pipelines
- Retrieval and generation components
- Routing and branching
- Tool-using agents
Limits to know
- Operating the pipeline requires engineering setup
- Model and infrastructure charges are separate
AI agent platform for coordinating experts and recurring work, with a self-hosted path and managed service.
Best for: Agent coordination and Recurring tasks
Free plan: No permanent free hosted plan: eligible new accounts get a 7-day Pro trial (card required, no charge at signup). Pro is $50/month ($510/year) after the trial; Max is $320/month. Workflow runs use a credit wallet. Self-hosting is free via Docker but you supply infrastructure and model access.
Key features
- Agent coordination
- Recurring tasks
- Connected tools
- Self-hosted deployment
Limits to know
- Self-hosting requires your own infrastructure and model keys. Platform code uses Polyform Shield; classic components use MIT. Managed service access and model costs are separate.
Quick decision guide
- Prefer open source? Browser Use, Agno, Flowise, Mastra, Pydantic AI, Haystack.
Head-to-head comparisons
Frequently asked questions
If the framework is free, what do I pay for?
Model API usage, hosting and any managed cloud features. Self-hosting removes platform fees but not model costs.
Which framework should a beginner start with?
Visual builders are easier to start with. Code libraries give more control once you know what your agent needs to do.
Which open-source agent frameworks here need no credit card?
We have not confirmed a no-card sign-up for tools in this list. Check each provider's sign-up page, and see our guide to free AI tools with no credit card required.
How current is this list?
Tool details were last reviewed 2026-10-15 from official pages. Free plans change often, so check the linked pricing page before you rely on a limit.