Sim
Apache-2.0 n8n alternative
Details
- External ID
- 46234186
- Source
- HN
- Company
- —
- Product
- Sim
- Website domain
- github.com
- Launched
- Dec. 11, 2025
- Cohort
- —
- Upvotes
- 240
- Upvotes percentile
- 0.9599236641221374
- Tags
- —
- Fetched at
- Sept. 7, 2026, 9:25 p.m.
- Updated at
- Sept. 7, 2026, 9:25 p.m.
Description
Hey HN, Waleed here. We're building Sim (https://sim.ai/), an open-source visual editor to build agentic workflows. Repo here: https://github.com/simstudioai/sim/. Docs here: https://docs.sim.ai.You can run Sim locally using Docker, with no execution limits or other restrictions.We started building Sim almost a year ago after repeatedly troubleshooting why our agents failed in production. Code-first frameworks felt hard to debug because of implicit control flow, and workflow platforms added more overhead than they removed. We wanted granular control and easy observability without piecing everything together ourselves.We launched Sim [1][2] as a drag-and-drop canvas around 6 months ago. Since then, we've added:- 138 blocks: Slack, GitHub, Linear, Notion, Supabase, SSH, TTS, SFTP, MongoDB, S3, Pinecone, ...- Tool calling with granular control: forced, auto- Agent memory: conversation memory with sliding window support (by last n messages or tokens)- Trace spans: detailed logging and observability for nested workflows and tool calling- Native RAG: upload documents, we chunk, embed with pgvector, and expose vector search to agents- Workflow deployment versioning with rollbacks- MCP support, Human-in-the-loop block- Copilot to build workflows using natural language (just shipped a new version that also acts as a superagent and can call into any of your connected services directly, not just build workflows)Under the hood, the workflow is a DAG with concurrent execution by default. Nodes run as soon as their dependencies (upstream blocks) are satisfied. Loops (for, forEach, while, do-while) and parallel fan-out/join are also first-class primitives.Agent blocks are pass-through to the provider. You pick your model (OpenAI, Anthropic, Gemini, Ollama, vLLM), and and we pass through prompts, tools, and response format directly to the provider API. We normalize response shapes for block interoperability, but we're not adding layers that obscure what's happening.We're currently working on our own MCP server and the ability to deploy workflows as MCP servers. Would love to hear your thoughts and where we should take it next :)[1] https://news.ycombinator.com/item?id=43823096[2] https://news.ycombinator.com/item?id=44052766
Enrichment
- Theme
- developer tools for AI agents
- Vertical
- Horizontal
- Function
- Workflow automation
- Audience
- B2B
- AI stance
- Not AI
- Project type
- Commercial product
- Normalized one-liner
- workflow automation alternative to n8n
- Manually corrected
- False
Could you build this?
Partial While standard workflow builders are easy to scaffold, building a reliable, self-hosted agent execution engine with complex branching, sandbox isolation, and distributed task queues requires substantial systems engineering.
What it would actually take: A production version requires a node-based DAG editor (e.g., React Flow), a robust backend execution runtime (Node.js/Go) that handles cycle detection, state persistence, error retries, and sandboxed code execution (Docker or isolated VM runtimes). The hard part is building a fault-tolerant workflow orchestrator that can reliably execute arbitrary long-running, multi-step LLM agent pipelines with deterministic state recovery.
Discussion
20 comments analyzed.
Competitors mentioned: n8n, Node-Red, ActivePieces, LangGraph, Temporal
Concerns raised: LangGraph ecosystem maturity and tutorials vs new solutions, Documentation gaps for Docker images and configuration, LangGraph vendor lock-in attempts with proprietary CLI, Reliability/durability guarantees unclear for new workflow engines
Feature requests: Dark mode on main website, Better documentation for Azure OpenAI setup, Support for additional AI model providers beyond Azure, Prebuilt Docker images in compose.local file
Competitors
Other products that read as similar to this one — 281 launches clear the similarity bar, closest 8 shown.
Attention rank: #18 of 282 (itself plus its competitors, highest first — normalized so YC and Product Hunt are compared fairly).
Launched 38 days after the earliest competitor.
- Sim · ph · 2026-07-10 · 582 upvotes · similarity 0.59
- Running AI agents across environments needs a proper solution · hn · 2026-03-24 · 8 upvotes · similarity 0.47
- Crewship · hn · 2026-02-27 · 11 upvotes · similarity 0.45
- I built an open-source alternative to Claude Cowork · hn · 2026-07-02 · 39 upvotes · similarity 0.45
- Agentspace · hn · 2026-06-17 · 5 upvotes · similarity 0.44
- Orloj · hn · 2026-03-26 · 20 upvotes · similarity 0.43
- Zenflow · hn · 2025-12-16 · 33 upvotes · similarity 0.43
- Toone · ph · 2026-09-18 · 138 upvotes · similarity 0.42
Other launches for this product
- No other launches for this product.
Same idea, different domain
Nobody's really built a workflow automation tool for Real estate yet.