Show HN: Sim Studio – Open-Source Agent Workflow GUI
35 comments
·April 28, 2025monatron
Hi y'all. Love the idea and congratulations on your launch. I've used [n8n](https://github.com/n8n-io/n8n) for similar use cases in the past. Any differences in Sim Studio that you'd like to call out?
ekarabeg
Thank you! n8n has done really well over the last few years to simplify the workflow building process. I responded to this in a previous comment, but we believe the agent building process should be more open, meaning fewer abstractions between the interface and the model provider. We want our platform to be as lightweight as possible.
How this translates in the application is through features like allowing for custom tool calling with code execution, JSON schema input for response format, etc. I'd love to hear your thoughts using Sim Studio - let us know how we compare to the other workflow builders!
skeeter2020
> Building reliable, multi-step agent systems with current frameworks often gets complicated fast.
In my experience so far it's not just complicated, but effectively impossible. I struggle to get a single agent to reliably & consistently use tools, and adding n+1 agents is a error multiplier.
waleedlatif1
on our platform (for the providers that allow granular tool use control), you can actually 'force' certain tool calls and have the agent dynamically select others. this was a painpoint that we faced ourselves and were confused why any frameworks didn't allow granular tool use control if the provider allows it. try it out and let us know what you think
brene
I checked it out and it’s quite polished for a workflow builder. But I struggled for it to handle lists of content well. But I saw that’s already an ongoing feature request.
dr_kiszonka
It looks very nice. What happens when a flow that takes 1 minute to complete is triggered by three different Slack messages from different users one second apart. Are flow executions queued or executed in parallel? Is it configurable?
simple10
Congrats on the launch! Looking forward to playing with it.
Do you mind elaborating on what differentiates Sim Studio from n8n, Flowise, RAGFlow and other open source flow based AI automation platforms?
ekarabeg
Thanks! The main difference between Sim Studio and other open-source AI agent workflow builders is the level of abstraction used when creating agents.
For instance, n8n has a "memory" parameter, which is not an inherent parameter of LLMs. You can inject your agent's memories into the agent message history (or system prompt) - which is the most common scenario - but we give you control over that. We want to provide visibility, so everything that's exposed on the workflow canvas is exactly what's being executed in the background. Also, we think it's faster and more intuitive to get your workflow up and running in Sim Studio. I'd love your feedback, though! What do you think?
all2
This sounds like execution/variable resolution scopes in programming languages. I wonder if there are ideas from programming languages you could pick up and use?
ddon
Would be amazing to be able to design the workflow using your builder, and then export to code (and choose the language) and then copy paste the code into the project... just an idea.
waleedlatif1
this is something we've been looking into. curious, would you rather export the code into an existing agentic framework like crewai/langgraph, or have it exported as raw code? also, would you prefer if the code was exported block-by-block or the entire workflow altogether?
artem_zin
Youtube demo looks intriguing, I'm self-hosting n8n for exact this purpose with a home run LLM machine in a local k8s cluster (lol) but out of the box I can tell your tool surpasses AI integrations and workflow in n8n.
Quick glance at GitHub suggests that GitHub package for the Docker image is missing, let me know if you need help with that — happy to contribute!
vseplet
It's funny, but I solved a similar problem myself, but instead of n8n I came to write my own solution. I even noticed this post thanks to automation and llm. Likewise, I'll be glad to help!
waleedlatif1
thanks! that would be awesome to have, always welcome contributors :)
joshcsimmons
Congrats on the launch the tool looks phenomenal.
I’m conflicted because n8n does feel like the right level of abstraction but the UI and dated JS runtime environment are horrible. I don’t really want to write my own memory functionality for my AI agents but wondering if it’s worth it just to have a nicer UI and more modern JS env.
waleedlatif1
for ease of use, we are exploring a way to add in short-term and medium-term memory out of the box in a way that doesn't require us to inject anything into the agent's context unless the user explicitly wants to. for longer-term memory, we support popular vector DB's like pinecone and integrations with mem0
gitroom
This is pretty sick, I love having that much control without having to hack around a bunch of stuff.
waleedlatif1
thank you and exactly! that's why we built it. trigger it many different ways, swap out tools, models, etc. Just focus on the things that matter for agent performance and ignore everything else
gavmor
I'm sure that the complex logic and state management were not trivial to implement, but the link said GUI so I wanted to see some screenshots, but all I saw were two very dim simple forms.
This space is REALLY struggling to graduate from Gradio-like design sensibilities.
That being said, I'm looking forward to playing with this, congrats on the launch!
nico
The video linked in the post description shows everything pretty clearly, here: https://www.youtube.com/watch?v=JlCktXTY8sE
rancar2
The screenshot on the website are helpful, and it would be good to add them into the GitHub documentation as the OP mentioned.
waleedlatif1
thanks for the feedback! adding some screenshots to the docs showcasing more complex workflows we've created so far
deshraj
Congratulations, Emir and Waleed! This is exactly the kind of OSS tooling I’ve been waiting for. I’ve spent countless hours wrestling with multi-step agent workflows hidden inside monolithic prompts, and every iteration felt like shooting in the dark. Having a drag-and-drop, executable graph with built-in branching, loops, and observability is a game-changer.
waleedlatif1
thank you! check out the mem0 integration and let us know if you like the form factor. excited for you to check out the platform and let us know if it helps you wrangle those multi-step agent workflows.
Hi HN! We're Emir and Waleed, and we're building Sim Studio (https://simstudio.ai), an open-source drag and drop UI for building and managing multi-agent workflows as a directed graph. You can define how agents interact with each other, use tools, and handle complex logic like branching, loops, transformations, and conditional execution.
Our repo is https://github.com/simstudioai/sim, docs are at https://docs.simstudio.ai/introduction, and we have a demo here: https://youtu.be/JlCktXTY8sE?si=uBAf0x-EKxZmT9w4
Building reliable, multi-step agent systems with current frameworks often gets complicated fast. In OpenAI's 'practical guide to building agents', they claim that the non-declarative approach and single multi-step agents are the best path forward, but from experience and experimentation, we disagree. Debugging these implicit flows across multiple agent calls and tool uses is painful, and iterating on the logic or prompts becomes slow.
We built Sim Studio because we believe defining the workflow explicitly and visually is the key to building more reliable and maintainable agentic applications. In Sim Studio, you design the entire architecture, comprising of agent blocks that have system prompts, a variety of models (hosted and local via ollama), tools with granular tool use control, and structured output.
We have plenty of pre-built integrations that you can use as standalone blocks or as tools for your agents. The nodes are all connected with if/else conditional blocks, llm-based routing, loops, and branching logic for specialized agents.
Also, the visual graph isn't just for prototyping and is actually executable. You can run simulations of the workflows 1, 10, 100 times to see how modifying any small system prompt change, underlying model, or tool call change change impacts the overall performance of the workflow.
You can trigger the workflows manually, deploy as an API and interact via HTTP, or schedule the workflows to run periodically. They can also be set up to trigger on incoming webhooks and deployed as standalone chat instances that can be password or domain-protected.
We have granular trace spans, logs, and observability built-in so you can easily compare and contrast performance across different model providers and tools. All of these things enable a tighter feedback loop and significantly faster iteration.
So far, users have built deep research agents to detect application fraud, chatbots to interface with their internal HR documentation, and agents to automate communication between manufacturing facilities.
Sim Studio is Apache 2.0 licensed, and fully open source.
We're excited about bringing a visual, workflow-centric approach to agent development. We think it makes building robust, complex agentic workflows far more accessible and reliable. We'd love to hear the HN community's thoughts!