What is the best free alternative to Sim?
Windmill is the closest free alternative to Sim: same Workflow Automation sub-category, and it is free. Open-source, self-hostable with unlimited executions on the free tier
Best free Sim alternatives
Looking for a free alternative to Sim? Here are 9 workflow automation worth trying — 9 with a free tier. Sim itself is free.
| Tool | Sim (you searched) | Windmill | Langflow | Google Opal |
|---|---|---|---|---|
| Pricing | free | free | free | free |
| Best for | Visual canvas for building, deploying and monitoring AI agents and workflows | Open-source, self-hostable with unlimited executions on the free tier | Open source with 138k GitHub stars, free desktop app and free cloud account | Describe an app in plain language and Opal builds a shareable multi-step AI workflow |
| Visit | Open ↗ | Open ↗ | Open ↗ | Open ↗ |
Sim alternatives — straight answers
Are there free Sim alternatives?
Yes — 9 of the 9 alternatives listed here are free or freemium: Windmill, Langflow, Google Opal, Flowise, LangBot. None of them are paid-only.
Is Sim free?
Sim is free. There is no paid plan attached to it in the catalog.
How were these Sim alternatives chosen?
They are the other tools in Workflow Automation, then the rest of AI Agents & Automation, ordered free tiers first and capped at 9. There is no sponsorship and no paid placement in that ordering — only the pricing tier decides.
All Sim alternatives
Browse Workflow Automation →Windmill
Workflow Automation
✦ WhyA Sim alternative — Open-source, self-hostable with unlimited executions on the free tier.
- Open-source, self-hostable with unlimited executions on the free tier
- Turns scripts (Python/TS/Go/Bash/SQL) into flows and full internal apps
- Kubernetes/Docker/Fargate deployable with a hybrid seat+compute enterprise pricing model
Langflow
Workflow Automation
✦ WhyA Sim alternative — Open source with 138k GitHub stars, free desktop app and free cloud account.
- Open source with 138k GitHub stars, free desktop app and free cloud account
- Drag-and-drop visual builder for agents and RAG pipelines on top of LangChain primitives
- Deep integrations across major LLMs, vector DBs and Google Cloud/Slack/MongoDB
✦ WhyA Sim alternative — Describe an app in plain language and Opal builds a shareable multi-step AI workflow.
- Describe an app in plain language and Opal builds a shareable multi-step AI workflow
- Agent step for autonomous multi-step workflows and automated runs
- Chains prompts, Gemini/Veo/Imagen models and tools visually
- Available in 160+ countries, also inside the Gemini app as Gems
✦ WhyA Sim alternative — Drag-and-drop builder for chatbots, agents and RAG flows.
- Drag-and-drop builder for chatbots, agents and RAG flows
- Self-host free with Docker or npm, with many model and vector store integrations
- Agentflow for multi-agent orchestration
- Embeddable chat widget and API output
✦ WhyA Sim alternative — Builds AI bots for WeChat, QQ, Discord, Slack, Telegram and other chat platforms.
- Builds AI bots for WeChat, QQ, Discord, Slack, Telegram and other chat platforms
- Plugs into Dify, n8n, Coze and other workflow back ends
- Plugin system and web admin panel
- Free and open source, self-hosted
✦ WhyA Sim alternative — Open-source version of ByteDance's Coze agent builder with visual workflows.
- Open-source version of ByteDance's Coze agent builder with visual workflows
- Plugins, knowledge bases, databases and memory for agents
- Apache 2.0 licensed, self-hosted with Docker
- Connects to OpenAI and other model providers
✦ WhyA Sim alternative — Open-source platform for building LLM workflows, RAG and multi-agent apps.
- Open-source platform for building LLM workflows, RAG and multi-agent apps
- Strong document parsing with OCR, tables and layout analysis
- Loops, parallelism and human-in-the-loop steps
- Apache 2.0, self-hosted
Zapier
Workflow Automation
✦ WhyA Sim alternative — Connect 8,000+ apps with AI agents.
- Connect 8,000+ apps with AI agents
- Natural-language automation builder
- AI steps, chatbots and tables
- Free tier for basic Zaps
n8n
Workflow Automation
✦ WhyA Sim alternative — Open-source, self-hostable automation.
- Open-source, self-hostable automation
- Visual AI-agent and LLM nodes
- Full code when you need it
- Free to run yourself