FastMCP 3.0 Release Webinar

We sat down live to talk about FastMCP 3.0 — what changed, what broke, and why we rebuilt the whole thing from the inside out. • The beta was downloaded 140K times (opt-in only, not accidental installs). That's a strong signal of community trust and engagement. • 70% of all MCP servers across all languages are built with FastMCP. Big names like Snowflake, Databricks, and Motherduck depend on it. • The 3.0 rewrite was triggered by a conversation with one of Prefect's largest customers.They wanted to load tool definitions from a database, and the old architecture couldn't support it cleanly. Classic "customer need drives product" story. • New architecture (Providers + Transforms) makes it way easier to compose, customize, and scale MCP servers. Unlocks things like per-tool authorization, tool versioning, tool search, and code mode. • Minimal breaking changes. 95%+ of users should have zero issues upgrading. Migration guide + an LLM prompt that does the upgrade for you at gofastmcp.com. • What's next: MCP Apps (interactive UIs in the chat via Prefab), code mode, and continued investment in making FastMCP the default way to build MCP servers. • 21 new contributors in the 3.0 release alone. Community is growing fast. CONTENT 00:00 Intro & community thank you 02:30 What is FastMCP (for the uninitiated) 05:02 What was wrong with 2.x 07:41 The customer story that started it all 10:49 Providers and transforms explained 14:57 What this actually unlocks (code mode, search, namespacing) 18:19 Smaller delights — hot reload, quality of life stuff 19:33 Provider rundown (proxy, mount, open API, file system, skills) 22:15 Transform rundown (versioning, visibility, resources-as-tools) 26:12 Sampling fallbacks & OpenTelemetry 27:41 Breaking changes — what actually breaks 33:12 What's next: MCP apps, Prefab, and maybe code mode 38:12 Q&A starts 38:53 Per-tool authorization 39:09 Unmounting servers 40:58 FastMCP in Frontier 42:10 Registry support 44:04 Code review workflow & AI in the process 48:08 Prefab native app support 50:44 Code mode & sandboxing with Monty 53:16 A2A protocol thoughts 55:29 MCP apps & external URLs 57:17 Background tasks & closing Links: FastMCP 3.0 blog post — https://www.jlowin.dev/blog/fastmcp-3-launch Upgrade guide — https://gofastmcp.com/getting-started/upgrading/from-fastmcp-2 Prefab — prefab.prefect.io