Show HN: Sim – Apache-2.0 n8n alternative

164•waleedlatif1•12h ago

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

Comments

malcolmgreaves•10h ago

What does “n8n” stand for? I’m assuming it’s a shortening of a longer word, like k8s.

waleedlatif1•10h ago

i believe it stands for “nodemation”

beklein•9h ago

Correct, check the "Our name" section at: https://n8n.io/press/

isoprophlex•9h ago

naaathaaan

esafak•9h ago

Is that intoned like Ricardo Montalbán's "Khaaaan!" ?

donalhunt•4h ago

I think more "Fenton!"...

https://youtu.be/3GRSbr0EYYU

aquariusDue•5h ago

I've been pronouncing it as "nanites" in my head since the first time I've seen it. Dunno why and now I feel just a tiny silly, though I still prefer my pronunciation.

Needless to say I never had to actually say "n8n".

brene•9h ago

How does it deal with loops? I’ve often see workflow builders struggle at that?

Natfan•9h ago

and specifically nested loops. if you're spinning up full runtime copies for each loop, you're gonna have a hard time

waleedlatif1•9h ago

at the moment, we don't support 'loops in loops' on the client-side, but not for any other reason asides from it becoming confusing for users. since we don't actually make copies for each loop, it wouldn't be a performance issue.

waleedlatif1•9h ago

for loops we use two sentinel nodes with a backwards edge, and before each iteration, we check the condition and update loop variables.

  sentinel -> body -> sentinel (condition with backwards edge to first sentinel)

in the UI, this is just represented as another block, and depending on the varying types of loops you can either define a collection or the number of iterations

SCUSKU•9h ago

A bit of feedback, the readme gifs are a little too fast, it's hard to tell what exactly is happening.

waleedlatif1•9h ago

thanks for the feedback, I was actually thinking this the other day. we'll slow them down.

hbarka•7h ago

I wonder how the free open-source in this stacks up to the free open-source in n8n.

waleedlatif1•7h ago

n8n uses a "Sustainable Use License"—source available, but not OSI-approved open source. This means you can only use it for internal business purposes or non-commercial use. Sim is Apache 2.0.

threecheese•5h ago

Edit: I checked out your materials, I see. Copilot; smart - one could probably do this themselves with the self hosted, and those that would do this aren’t good customers for you. Those that don’t want to bother will use the free tier and possibly convert, and maybe you’ll get some enterprise out of the bargain. Good luck!

What is your business strategy, if someone like AWS could treat you like Elastic or Redis? Premium addons? As a consumer I have no problem with n8ns license, it’s their technology that I think could be done better by a fresh competitor.

waleedlatif1•3h ago

Copilot and a few modules are sim.ai-only, but self-hosters can access them with an API key. The core—execution engine, all integrations, deployment—is fully Apache 2.0.

We aimed for feature parity with n8n and improved much of the workflow building experience along the way. We also added what we think agentic workflows needed (mentioned above). Would love your feedback.

spflueger•7h ago

Looks interesting. The 12GB minimum RAM requirements seem quite steep though. Why so much?

waleedlatif1•6h ago

its a conservative estimate, but primarily because there's a socket server that runs alongside the main container, so you never have to manually save because changes are debounced, broadcasted to any other users on the canvas, and sent to the socket server which persists it to the DB

smarx007•6h ago

So here is a case that I wanted to implement in n8n a few years ago and it required quite heavy JS blocks:

- I want to check some input - pick one of your 138 blocks

- I want to extract a list of items from that input

- I want to check which items did I encounter before <- that's the key bit

- Do something for the items that have not been encountered before; bonus point for detecting updated and deleted items

- Rinse and repeat

It could be a row added to a CSV file, a new file dropped into a Nextcloud folder, a list of issues pulled from a repo, or an RSS feed (Yahoo! Pipes, what a sweet memory).

How good is the support for such a case in Sim? And did it get better in n8n?

nine_k•6h ago

But does that require AI agents? Well, maybe the extraction step, if it's not CSV but a general-case web page.

smarx007•5h ago

Maybe in the middle, processing the items - classifying, summarizing.

But the post bills the tool as an n8n alternative. Therefore, I am evaluating it as such. Solid basics before the AI whizbang.

waleedlatif1•5h ago

the agents would be great in the instructions where we need to `do something`, but asides from that is sounds like a pure orchestration task.

now, handling an integration to something like google sheets myself for a task this small is a nightmare, not to mention the separate table I'd need to keep to store the access token & refresh token and the permissions I'd need to get from google. on top of that, hosting it somewhere and then monitoring it.

waleedlatif1•5h ago

this is actually a perfect use case, mostly deterministic workflows that need LLMs to fill in the gaps or do the knowledge work. As you mentioned, you can either add it as a row in a CSV file (sheets), use the baked-in memory block and treat it as simple storage, store the row in supabase, or use the knowledgebase. Basically, there are a ton of ways that this can be done that don't require you to maintain the memory solution yourself. you can even detect the updated and deleted items by keeping some sort of version-controlled snapshot of each row in the csv and updating it as you go.

I can't tell you whether it got better in n8n, but I can definitively say that this sounds like a great candidate workflow to build in sim :)

vulture916•4h ago

N8n can definitely do this.

They recently added native tables, albeit still just a few data types, you can store stuff in and use in workflows.

grantith•4h ago

I really like windmill.dev which should support your scenario just fine

itayd•3h ago

Hey - could be a good use case for https://github.com/autokitteh/autokitteh - which gives you durable workflows over python. Since your logic is deterministic it's a simple python script that stores the history in memory, and autokitteh will take care of the persistancy aspect.

solarkraft•5h ago

This looks really cool for DIYing workflows, especially since you seem to have a very useful selection of tools!

Did you build your own agent engine? Why not LangGraph?

Say I was building a general agentic chat app with LangGraph in the backend (as it seems to provide a lot of infrastructure for highly reliable and interactive agents, all the way up to a protocol usable by UIs, plus a decent ecosystem, making it very easily extensible). Could I integrate with this for DIY workflows in a high quality fashion (high-precision updates and control)?

Is there a case for switching out LangGraph‘s backend with Sim (can you build agents of the same quality and complexity - I’m thinking coding agent)? Could it interact with LangGraph agents in a high quality way so you can tap that ecosystem?

Can I use Sim workflows with my current agent, say, via MCP?

threecheese•5h ago

Their deployment stuff has been turning me off lately; everyone is rushing to monetize - which I understand and support - but I feel like Langsmith is creeping further and further into Langchain|graph and it makes me hesitant to invest. It’s giving AWS-like gentle but firm lock-in vibes, I wonder if they have any PMs from there.

I do like the way they’ve been able to leverage Langgraph workflows to build agents - it seems like the right abstraction to me - and I also feel their middleware approach is very Django-y which I also like. Are you enjoying their stack?

waleedlatif1•5h ago

1. we wanted to have full control over the agent orchestration and the execution since we didn't like the abstractions that many of the existing frameworks had built, and didn't want to have dependencies in places we didn't need them. so, we built the orchestration and execution engine from scratch, allowing us to do neat things like human in the loop, settings that run the same block 10 times concurrently, etc.

2. this would kind of serve as a drop-in replacement for langgraph. you could build a workflow with an agent and some tools, perhaps some form of memory. then, just deploy that as an API, call it from your frontend, and consume the streamed response on your chat client and without the need to maintain any infra at all.

3. we have a generic code block and an api block used to call APIs for integrations that we may not have, and you can use those to plug (langgraph) agents into the Sim ecosystem.

4. we are adding in the ability to deploy your workflow as an MCP server in the next week, stay tuned :) in the meantime, you can deploy the workflow as an API and have the agent call it as a tool. moreover, you can use the workflow block in sim to call other agents/worklows as well, so its easy to encapsulate a lot of complexity in a `parent` workflow that you call that dynamically routes and uses different tools based on the task at hand

saubeidl•4h ago

How does this compare to say, Node Red?

waleedlatif1•3h ago

Node-RED is great for IoT/edge/data flows. Sim is built specifically for AI agents—native LLM support, tool-use control, structured outputs, token-level observability, etc.

Multicomp•1h ago

Excited to try this out, I've been looking at LangFlow and similar tools for doing DAG workflows. Sure, I could prompt or try to do an MCP or a claude skill for my utility workflows, but they aren't strongly followed and I want to, where possible, make each AI agent call be smaller, like a function.

This is definitely going to be given a try tomorrow morning. I think first up will be something easy and personal like going through the collection of NPC character sheets in my recent campaign and ensuring all NPCs have the following sections with some content in them, and if not, flagging them for my review.

waleedlatif1•1h ago

sounds super cool! let me know how it goes

greggh•7m ago

Development seems pretty rapid, how often are breaking changes forcing workflow modifications to keep updated with the latest versions?

popalchemist•7m ago

> You can run Sim locally using Docker, with no execution limits or other restrictions.

This is big. Thank you.

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Show HN: Sim – Apache-2.0 n8n alternative

Comments

Show HN: Sim – Apache-2.0 n8n alternative

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