Developers

MCP server

Grind conversion as a callable tool. Connect it to Claude, ChatGPT or any MCP client and the assistant can work out the setting for the grinder in front of the person asking, instead of quoting a chart for a different one.

Endpoint

https://brewmark.io/api/mcp

Streamable HTTP, JSON-RPC 2.0 over POST. No authentication, no API key, no rate tier — it is read-only and public. The same maths the website runs, so a conversion here and a conversion on a grinder page cannot disagree.

Tools

convert_grind_setting(from, setting, to)

A setting on one grinder translated to the equivalent on another.

get_grinder_chart(grinder)

One grinder’s full dial-in chart, espresso through cold brew, with usable ranges.

list_grinders(search (optional))

Every supported grinder with its slug. Call this when the user names a grinder in prose.

Claude Desktop

Add to claude_desktop_config.json:

{
  "mcpServers": {
    "brewmark": {
      "type": "http",
      "url": "https://brewmark.io/api/mcp"
    }
  }
}

Claude Code

claude mcp add --transport http brewmark https://brewmark.io/api/mcp

ChatGPT

Enable Developer Mode (Plus or Pro), then add a connector pointing at the endpoint above.

Try it without a client

list the tools

curl -X POST https://brewmark.io/api/mcp \
  -H 'Content-Type: application/json' \
  -d '{"jsonrpc":"2.0","id":1,"method":"tools/list"}'

convert a setting

curl -X POST https://brewmark.io/api/mcp \
  -H 'Content-Type: application/json' \
  -d '{"jsonrpc":"2.0","id":2,"method":"tools/call","params":{
        "name":"convert_grind_setting",
        "arguments":{"from":"comandante-c40-mk4","setting":18,"to":"baratza-encore"}}}'

There is a plain REST equivalent too, if you would rather not speak JSON-RPC: /api/v1/convert?from=…&setting=…&to=…

Where the numbers come from

Every grinder is mapped onto a shared 0–100 grind index — 0 espresso-fine, 40 filter, 100 coarsest — from five reference points per model. Those come from the manufacturer’s published grind chart where one exists, and from what experienced users report where it does not. They are a starting point, not a measurement: burr wear, bean density and roast level all move the target, which is why every answer carries a range as well as a number.

REST API documentation →The converter as a web tool →All grinder charts →