Yes. The ExpertToolkit MCP server and public REST API are free to use. There is no paywall, no usage tier, and no cost to connect it to your AI assistant.

AI assistant connector

Use ExpertToolkit inside ChatGPT, Claude & Cursor

Q: Which AI assistants work?

Any client that supports the Model Context Protocol (MCP). This includes ChatGPT (Plus and Pro with developer mode), Claude Desktop and Claude.ai custom connectors, Cursor, Windsurf, and other MCP-compatible tools.

Call ExpertToolkit's calculators, unit converters, and USDA nutrition data directly from your AI assistant. It connects over the Model Context Protocol (MCP) — free, with no sign-up and no API key.

MCP endpoint

https://mcp.experttoolkit.net

What you can do

Nine tools, grouped by what they solve. Ask in plain language and your assistant picks the right one.

Unit conversion

convert_units
Convert 10 meters to feet, or 2 cups of flour to grams.
search_units
Find every unit that measures pressure or energy.

Calculators

calculate_mortgage
Monthly payment on a $400k loan at 6.5% over 30 years.
calculate_loan_payment
Amortized payment for any principal, rate, and term.
calculate_compound_interest
Grow $10k at 7% compounded monthly for 20 years.
calculate_bmi
Body Mass Index from height and weight, metric or imperial.

Nutrition (USDA data)

nutrition_lookup
Macros and calories for raw chicken breast per 100 g.
nutrition_serving
Protein and calories for a specific serving size.
nutrition_compare
Compare chicken breast vs turkey breast side by side.

Set up your assistant

Every client uses the same endpoint with no authentication.

ChatGPT (Plus / Pro)

Open Settings and enable Developer mode under Connectors (or Plugins).
Choose Add connector / Add custom connector.
Paste the MCP endpoint URL below and select No authentication.
Save, then ask ChatGPT to convert a unit or run a calculation.

https://mcp.experttoolkit.net

Claude Desktop / Claude.ai

Open Settings then Connectors.
Choose Add custom connector.
Paste the MCP endpoint URL below (no auth required) and save.
Start a chat and ask Claude to use an ExpertToolkit tool.

https://mcp.experttoolkit.net

Cursor, Windsurf & other MCP clients

Add ExpertToolkit to your MCP configuration file (for example Cursor's mcp.json):

JSON

{
  "mcpServers": {
    "experttoolkit": {
      "url": "https://mcp.experttoolkit.net"
    }
  }
}

Also available

Public REST API

Prefer a plain HTTP call? Convert units with a simple GET request — no key required.

GET

https://www.experttoolkit.net/api/v1/convert?from=meter&to=foot&val=10

llms.txt

A machine-readable index of ExpertToolkit for AI crawlers and agents that follow the llms.txt convention.

View /llms.txt

Frequently asked questions

Is it free?
Yes. The ExpertToolkit MCP server and public REST API are free to use — no paywall, no usage tier, and no cost to connect it to your AI assistant.
Which AI assistants work?
Any client that supports the Model Context Protocol (MCP): ChatGPT (Plus and Pro with developer mode), Claude Desktop and Claude.ai custom connectors, Cursor, Windsurf, and other MCP-compatible tools.
Do I need to sign up?
No. There is no account, sign-up, or API key required. The MCP endpoint uses no authentication — you just add the URL to your assistant.
Are the numbers accurate?
Yes. Conversions map to NIST and BIPM standard definitions, calculators use published financial and health formulas, and nutrition data comes from the USDA dataset — the same engines that power the ExpertToolkit website.

Prefer to use the tools directly?

Every calculator and converter is also on the web — no setup needed.

Browse calculators Browse converters

What you can do

Nine tools, grouped by what they solve. Ask in plain language and your assistant picks the right one.

Unit conversion

convert_units
Convert 10 meters to feet, or 2 cups of flour to grams.
search_units
Find every unit that measures pressure or energy.

Calculators

calculate_mortgage
Monthly payment on a $400k loan at 6.5% over 30 years.
calculate_loan_payment
Amortized payment for any principal, rate, and term.
calculate_compound_interest
Grow $10k at 7% compounded monthly for 20 years.
calculate_bmi
Body Mass Index from height and weight, metric or imperial.

Nutrition (USDA data)

nutrition_lookup
Macros and calories for raw chicken breast per 100 g.
nutrition_serving
Protein and calories for a specific serving size.
nutrition_compare
Compare chicken breast vs turkey breast side by side.

Set up your assistant

Every client uses the same endpoint with no authentication.

ChatGPT (Plus / Pro)

Open Settings and enable Developer mode under Connectors (or Plugins).
Choose Add connector / Add custom connector.
Paste the MCP endpoint URL below and select No authentication.
Save, then ask ChatGPT to convert a unit or run a calculation.

https://mcp.experttoolkit.net

Claude Desktop / Claude.ai

Open Settings then Connectors.
Choose Add custom connector.
Paste the MCP endpoint URL below (no auth required) and save.
Start a chat and ask Claude to use an ExpertToolkit tool.

https://mcp.experttoolkit.net

Cursor, Windsurf & other MCP clients

Add ExpertToolkit to your MCP configuration file (for example Cursor's mcp.json):

JSON

{
  "mcpServers": {
    "experttoolkit": {
      "url": "https://mcp.experttoolkit.net"
    }
  }
}

Also available

Public REST API

Prefer a plain HTTP call? Convert units with a simple GET request — no key required.

GET

https://www.experttoolkit.net/api/v1/convert?from=meter&to=foot&val=10

llms.txt

A machine-readable index of ExpertToolkit for AI crawlers and agents that follow the llms.txt convention.

View /llms.txt

Frequently asked questions

Is it free?

Yes. The ExpertToolkit MCP server and public REST API are free to use — no paywall, no usage tier, and no cost to connect it to your AI assistant.

Which AI assistants work?

Any client that supports the Model Context Protocol (MCP): ChatGPT (Plus and Pro with developer mode), Claude Desktop and Claude.ai custom connectors, Cursor, Windsurf, and other MCP-compatible tools.

Do I need to sign up?

No. There is no account, sign-up, or API key required. The MCP endpoint uses no authentication — you just add the URL to your assistant.

Are the numbers accurate?

Yes. Conversions map to NIST and BIPM standard definitions, calculators use published financial and health formulas, and nutrition data comes from the USDA dataset — the same engines that power the ExpertToolkit website.