Sim
An open-source workspace for building and running AI agent workflows
Overview
Sim is what you get when someone decides Zapier should be able to think. It's an open-source tool for building AI agent workflows visually: drag out blocks, wire them to Slack or your CRM or a database, point them at whichever LLM you like, and let the agent run. It has real traction, with around 29,000 GitHub stars and a 4.7 rating across 100+ reviews on Product Hunt, so this isn't a weekend side project. It's also genuinely self-hostable, which matters if you don't want your workflow data sitting on someone else's server.
That said, Sim is built for people comfortable with tools, APIs, and a bit of technical fiddling, not for someone who just wants a chatbot for their blog. Reviewers describe the documentation and edge-case handling as still maturing, which tracks for a young, fast-moving open-source project. If you want a mature, hand-holding no-code tool, look elsewhere. If you want a flexible, self-hostable agent builder and don't mind some rough edges, Sim is worth a serious look.
Key Features
Visual Workflow Canvas: Build agent workflows by connecting blocks, tools, and agents on a drag-and-drop canvas.
1,000+ Integrations: Connect to Slack, HubSpot, Salesforce, Notion, and hundreds more without custom code.
Any LLM, Any Model: Works with every major LLM provider, plus local models via Ollama and vLLM for fully offline runs.
Built-In Data Layer: Tables, files, and knowledge bases live in the same workspace as your workflows.
Monitoring and Logs: Live traces, execution logs, and cost tracking so you can see what an agent actually did.
Self-Hostable: Fully open-source (Apache 2.0), so you can run it on your own infrastructure instead of trusting a vendor with your data.
Pricing
Starting price
$25/mo
Free: $0 forever. 1,000 monthly credits, 1 workspace, 5GB file storage.
Pro: $25/user/month. 6,000 monthly credits, 3 workspaces, 50GB storage, unlimited log retention.
Max: $100/user/month. 25,000 monthly credits, unlimited workspaces, 500GB storage, adds Sim Mailer, KB Live Sync, and Slack Connect.
Enterprise: Custom pricing. Unlimited everything, plus SSO, SOC2 compliance, self-hosting, and dedicated support.
Disclaimer: pricing may change, confirm current pricing on Sim's own pricing page before buying.
Pros
Genuinely Open Source: Apache 2.0 licensed and self-hostable, not just "open core" marketing.
Huge Integration List: Reviewers repeatedly call out the sheer number of connected apps as a standout.
Real Free Tier: 1,000 monthly credits and a full workspace before you pay anything.
Local Model Support: Runs with Ollama or vLLM, so you can build entirely offline if you need to.
Strong Early Traction: Around 29,000 GitHub stars and a 4.7 rating from 100+ Product Hunt reviews.
Cons
Docs Still Maturing: Reviewers flag documentation and edge-case error handling as rough around the edges for a young project.
Not For Beginners: The visual builder helps, but you still need to understand APIs, integrations, and workflow logic to get real use out of it.
Per-Seat Pricing Adds Up: Paid tiers are priced per user per month, which climbs fast for a small team that wants everyone in the workspace.
Thin Independent Coverage: Most detailed reviews so far come from Product Hunt and smaller AI blogs, not established third-party publications, so long-term reliability is still unproven.
What Makes It Unique
Truly Self-Hostable and Open Source: Unlike most agent-building platforms that lock workflows into a hosted SaaS, Sim is Apache 2.0 licensed and runs on your own infrastructure if you want it to.
Kay Score
7
/ 10
Tool Information
Pricing
$25/mo
Category
Automation & AI Agents
Platform
Web / iOS / Android
Last Updated
