# Sim

7 Hacker News commenters recommended Sim and 1 criticized it, November 2025 to November 2026. It was recommended in 1 of 13 months.

**Verdict:** Open-source AI agent workflow builder with native LLM support, debug mode, and an Apache 2.0 core. Caveats: a 12GB minimum RAM requirement and no custom LLM endpoints in the Copilot.

## Why people recommend it

- Built for AI agent workflows (2 comments): "Sim is built specifically for AI agents—native LLM support, tool-use control, structured outputs, token-level observability" ([source](https://news.ycombinator.com/item?id=46239970)) "allowing us to do neat things like human in the loop" ([source](https://news.ycombinator.com/item?id=46239238))
- Stable, open-source core and cloud (2 comments): "The core—execution engine, all integrations, deployment—is fully Apache 2.0." ([source](https://news.ycombinator.com/item?id=46240017)) "We keep all workflows running on Sim cloud backwards compatible always." ([source](https://news.ycombinator.com/item?id=46241245))

## What people warn about

- Cannot use own LLM endpoints in Copilot (1 comments): "not being able to use my own LLM endpoints for the Copilot is an instant turn-off" ([source](https://news.ycombinator.com/item?id=46241968))
- High 12GB minimum RAM requirement (1 comments): "The 12GB minimum RAM requirements seem quite steep though." ([source](https://news.ycombinator.com/item?id=46237417))
- Doubts about long-term business strategy (1 comments): "What is your business strategy, if someone like AWS could treat you like Elastic or Redis?" ([source](https://news.ycombinator.com/item?id=46239260))

## Alternatives hackers recommend

- [Node-RED](https://hackerapproved.com/p/node-red.md): 13 recommend
- [Graph Compose](https://hackerapproved.com/p/graph-compose.md): 7 recommend
- [Pipedream](https://hackerapproved.com/p/pipedream.md): 5 recommend

## Cite as

Hacker Approved, "Sim", https://hackerapproved.com/p/sim/ (counts from 1,795,640 Hacker News comments, November 2025 to November 2026).