fastmcp Releases

An update introducing feed spider templates and upgrading the MCP server to SDK v2 for better AI integration.

Aug 9, 2026

Introduces a new configuration option to maintain stream connections during long-running tool executions.

Aug 9, 2026

Enforces authentication requirements on the Server-Sent Events (SSE) endpoint.

Aug 8, 2026

Introduces a new configuration option to enforce S256 code challenges in OAuth flows.

Aug 7, 2026

Fixes a resource management issue in the OAuthProxy cleanup process.

Aug 7, 2026

Implements constant-time comparison for PKCE challenge validation to mitigate timing attacks.

Aug 7, 2026

Fixes a concurrency issue in authentication by ensuring refresh token mappings are consumed atomically during swap mode operations.

Aug 5, 2026

Improves error handling in OAuth proxy endpoints to properly manage aborted and oversized request bodies.

Aug 5, 2026

Adds timeout handling to image and audio content fetching to prevent indefinite hanging.

Aug 4, 2026

Includes multiple stability improvements such as timeouts for OAuth/discovery fetches, scope normalization in JWKS, and better reporting for unsupported tool schemas.

Aug 4, 2026

This release addresses a security vulnerability by implementing timing-safe comparison for JWT and consent signatures to prevent timing attacks.

Aug 1, 2026

Unifies the cloud backend with paginated listings and introduces new CLI commands for improved sandbox management and connectivity.

Jul 29, 2026

This release upgrades the final response mechanism to a structured finalization protocol with explicit evidence strategies to prevent intermediate agent outputs from being mistaken for completion.

Jul 28, 2026

Jul 28, 2026

This release fixes an issue where SessionError and FastMCPError were not exported from the main package, improving library usability for consumers.

Jul 27, 2026

A release focused on making spiders smarter with an AutoThrottle feature and adding CSV/XML exporters.

Jul 26, 2026

Enhances network stability, adds CLI management tools, and improves filesystem and snapshot handling with sparse archive support.

Jul 25, 2026

This release introduces a new `FastMCP.connect` method that allows users to establish connections using custom transports, enhancing the framework's flexibility for different integration scenarios.

Jul 25, 2026

The release exposes internal implementation details, specifically progress messages and document stream content, as non-standard features to give developers more control over their MCP implementations.

Jul 25, 2026

A comprehensive update focusing on Web API enhancements, CDP improvements, and stability fixes for the browser engine, including a Zig 0.16 upgrade and performance optimizations.

Jul 25, 2026