60–70% of YC X25 Agent Startups Are Using TypeScript

I recently saw a tweet from Sam Bhagwat (Mastra AI's Founder) which mentions that around 60–70% of YC X25 agent companies are building their AI agents in TypeScript.

This stat surprised me because early frameworks like LangChain were originally Python-first. So, why the shift toward TypeScript for building AI agents?

Here are a few possible reasons I’ve understood:

- Many early projects focused on stitching together tools and APIs. That pulled in a lot of frontend/full-stack devs who were already in the TypeScript ecosystem.

- TypeScript’s static types and IDE integration are a huge productivity boost when rapidly iterating on complex logic, chaining tools, or calling LLMs.

- Also, as Sam points out, full-stack devs can ship quickly using TS for both backend and frontend.

- Vercel's AI SDK also played a big role here.

I would love to know your take on this!