freeCodeCamp.org — searchable YouTube transcripts & AI Q&A

MCP Security Fundamentals Course

Dan Barona argues that MCP security fundamentally hinges on breaking the "lethal trifecta"—the combination of private data access, untrusted content ingestion, and external communication—because any agent with all three is structurally vulnerable to data exfiltration. He illustrates this with real-world attacks like the Postmark MCP that silently BCC'd emails to an attacker and the GitHub MCP incident where a planted file redirected an agent to leak private repos. The course provides a practical framework, including the OWASP MCP Top 10 and a trifecta scorecard, to identify and mitigate these risks.

PostgreSQL Hybrid Search Course – Keyword (BM25) + Vector Retrieval

Hybrid search combining BM25 keyword ranking with vector-based semantic search can improve results, but it requires careful evaluation rather than assuming it always helps. The course demonstrates building a Wikipedia search app in PostgreSQL, using reciprocal rank fusion to merge the two ranked lists, and shows that while hybrid search can rank relevant articles higher, its effectiveness depends on the query and coverage of the embedding set. The speaker emphasizes testing changes one at a time and comparing results across methods.

Building an AI Data Center – Grid Power, Liquid Cooling, & Cloud Economics

The speaker argues that building an AI data center is a complex engineering challenge that requires coordinating power, cooling, and networking, with the central goal of converting raw megawatts into tokens efficiently. He explains that liquid cooling is now essential because water can absorb much more heat than air, and he details how power flows from the grid through transformers and UPS systems to the GPU, emphasizing that increasing voltage rather than current reduces heat loss. He also highlights that behind-the-meter gas turbines and modular construction are key strategies to bypass grid interconnection delays, and that the economics of AI data centers depend on tokens per watt and committed contracts.

Design Software Systems Like a Senior Engineer – Complete Course

The speaker argues that system design interviews are won by using a repeatable five-step framework—clarify requirements, design data/API, sketch high-level architecture, discuss scale and failures, and wrap up with trade-offs—rather than by memorizing specific architectures. He demonstrates the framework on three real-world systems, emphasizing that interviewers score candidates on communication, structured thinking, technical judgment, practical depth, and time management, not just the final design. He also stresses that every technology choice must be justified by trade-offs, and that candidates should treat the interview as a collaborative conversation with the interviewer.

n8n Full Course – Architect Scalable AI Automations from Scratch

n8n is not just another automation tool like Zapier but a full automation infrastructure and orchestration engine for building scalable, intelligent workflows. The course demonstrates how to build production-ready systems such as AI agents, event-driven pipelines, human-in-the-loop approvals, and self-hosted deployments, emphasizing that real-world automation requires monitoring and error handling to avoid silent failures.