The archive · Developer & Business Tools · Product decision · 2025–2026
Sim bets teams build AI agents on a visual canvas; YC X25 open-source tool raises $7M
YC X25 standout Sim makes a Figma-like open-source canvas for AI agent workflows; $7M Series A, 60k+ developers, 100+ companies by Nov 2025.
Sim (Sim Studio)
What the business is
Open-source visual platform for building AI agent workflows: a Figma-like canvas where teams connect models, tools and custom functions, then deploy workflows as APIs or chat interfaces.
Starting capital：$7M Series A led by Standard Capital (Nov 2025), with Perplexity Fund, SV Angel and Y Combinator participating, plus angels including Paul Graham.
How it started
Emir Karabeg and Waleed Latif, UC Berkeley alumni, were working on an AI-powered sales product whose agents.ts file had grown to thousands of lines — every new model meant rewriting orchestration by hand. They concluded the problem wasn't their product but the lack of a good way to build agents. Right after Emir graduated, he called Waleed at Amazon: 'Come to SF and let's build this.' They started hacking in January 2025, first goal: 10 GitHub stars.
What happened
Sim went through YC's first-ever Spring 2025 batch (X25), where TechCrunch named it one of 11 Demo Day standouts — an open-source AI agent builder aiming to do for agents what Figma did for design, with users including Epiq, Mercore and the U.S. Department of Defense. The team spent the batch on growth, ending with 4,000 GitHub stars, then launched a hosted platform (5,000+ waitlist) and a $7M Series A led by Standard Capital with Perplexity Fund, SV Angel, Y Combinator and angels including Paul Graham participating. By November 2025: 18,000 GitHub stars, 60,000+ developers, 100+ companies in production, 10M+ workflows processed.
How it ended up
Still scaling: the open-source repo and hosted workspace (sim.ai) continue to grow after the Series A; revenue figures are not disclosed.
Background
Sim (formerly Sim Studio) is an open-source platform for building AI agent workflows on a visual canvas. Founded in early 2025 by UC Berkeley alumni Emir Karabeg and Waleed Latif, it lets teams connect models, tools and custom functions like blocks in a Figma-style editor, then deploy the workflow as an API, a chat interface or a webhook-triggered service.
The origin was a dogfooding failure: the founders' AI sales product had an agents.ts file with thousands of lines, rewritten by hand for each new model. They concluded the industry's real problem was orchestration, quit their jobs (Emir calling Waleed at Amazon to move to San Francisco), and rebuilt their stack as Sim. It went through Y Combinator's first-ever Spring 2025 batch (X25), where TechCrunch picked it as one of 11 Demo Day standouts, noting users including Epiq, Mercore and the U.S. Department of Defense.
The bet is that agents are built visually with code-level power, not with boilerplate frameworks or locked-down no-code tools. Open source from day one (Apache 2.0), Sim grew from 0 to 18,000 GitHub stars, 60,000+ developers and 100+ companies in production within months, processing 10M+ workflows. In November 2025 it raised a $7M Series A led by Standard Capital with participation from Perplexity Fund, SV Angel, Y Combinator and angels including Paul Graham.
What has to be true
- The pain was first-hand: thousands of lines in agents.ts, rewritten for every new model, showed the founders that orchestration — not their product — was the bottleneck.
- Open source removed adoption friction: 0 to 18,000 GitHub stars and 60,000+ developers in months let distribution ride the repo instead of a sales team.
- Positioning split the difference: the canvas keeps code capabilities (custom functions, forced tool calls, parallel execution) that no-code builders drop, while removing the boilerplate of SDKs.
- YC X25 gave distribution focus: a 10-star goal became 4,000 stars by Demo Day, and users grew to include Epiq, Mercore and the U.S. Department of Defense, per TechCrunch.
What can be applied
Dogfood a painful internal problem into a product: a platform born from the founders' own unmanageable agents.ts file shipped open source, letting adoption spread from a single repo.
Aftermath
As of late 2025, Sim had 60,000+ developers on the platform, 100+ companies using it in production and 10M+ workflows processed, and was hiring across engineering after its $7M Series A. The project remains open source (Apache 2.0) with a hosted workspace at sim.ai; revenue figures are not disclosed.
Sources
- 11 startups from YC Demo Day that investors are talking about
- $7M Series A
- Sim.ai Series A led by Standard Capital
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