everything
**[Architecture](docs/architecture.md)
Discovery Score
60/100
83,995 stars
10,424 forks
The Open Source Drop Lens
A test and demo server that exercises every MCP capability: tools, resources, prompts, sampling, logging, completions. It exists so developers building MCP clients can verify their implementation handles all protocol features.
You get synthetic endpoints for every MCP feature type. Useful for integration testing and learning the protocol shape. Zero setup, zero config. Completely free with no underlying costs.
Maintained by the official Model Context Protocol team. This is not a production tool. It is a reference implementation for MCP client developers. If you are building or debugging an MCP client, grab it. Otherwise, skip it.
Cost Breakdown
## Free Tier The MCP server itself is completely free and open source.
## Self-Hosted Runs locally or on your own infrastructure.
## Paid No paid tier. The underlying service may have its own pricing.
Free and open source. The underlying service may have its own costs.
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