The guy who taught Abhi JavaScript is back!
Guil Hernandez has spent 15+ years teaching developers. His courses at Treehouse, Scrimba, and LinkedIn Learning have reached over 500,000 learners — including Abhi and Shane, who both learned JavaScript and CSS from him. He just released Mastra's first video course at https://mastra.ai/learn, and it's free.
"Build Your First Agent in TypeScript" is a 90-minute, hands-on course that takes you from zero to a deployed agent. Fourteen lessons across five sections: agents, tools, workflows, memory, and production. The project is a theme park planner agent — pulls live wait times, weather, and park hours, keeps track of what you like, and builds you an itinerary. Everything runs in Mastra Studio, so you can inspect traces, tool calls, and behavior as you go.
You'll see how to wire up local tools and MCP servers side by side, how message history and observational memory change agent behavior, how to compose a workflow for a mock ticket purchase, and how to expose the whole thing as an HTTP server with one-click Slack integration.
Guil also shares his broader take on teaching AI engineering. The mechanics — syntax, boilerplate, wiring — are no longer the hard part. What matters now is how you think through a problem, whether you have the taste to spot bad output, and when to take the handoff from the AI instead of iterating forever.
The gap between people who just generate output and people who can actually shape it keeps widening. This course is built for the second group.
Start here: https://mastra.ai/learn
👤 GUIL
https://x.com/guilh
https://guilhernandez.com
📚 MASTRA RESOURCES
Mastra: https://mastra.ai
Mastra on X: https://x.com/mastra_ai
Mastra Discord: https://mastra.ai/community/discord
Mastra GitHub: https://github.com/mastra-ai
Learn Mastra in the world's first MCP-based course: https://mastra.ai/course
Build Your First Agent in TypeScript — new video course: https://mastra.ai/learn
Principles of Building AI Agents (Book): https://mastra.ai/books/principles-of-building-ai-agents
Patterns for Building AI Agents (New Book): https://mastra.ai/books/patterns-of-building-ai-agents
MASTRA?
Mastra is an open-source TypeScript framework designed for building and shipping AI-powered applications and agents with minimal friction. It supports the full lifecycle of agent development—from prototype to production. You can integrate it with frontend and backend stacks (e.g., React, Next.js, Node) or run agents as standalone services. If you're a JavaScript or TypeScript developer looking to build an agentic or AI-powered product without starting from first principles, Mastra provides the scaffolding, tools, and integrations to accelerate that process.
📌 CHAPTERS
00:00 — Meet Guil
01:49 — Inside the course: the theme park agent
05:11 — Why Guil built this course
05:52 — Teaching AI engineering vs teaching React
09:30 — AI and the Socratic way of learning
10:01 — The gap between generating output and shaping it
11:09 — Who the course is for
12:37 — Keeping a course current when Mastra ships weekly
