Athanor by arbastro
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A free chemistry MCP server for your AI assistant

Athanor’s MCP server gives Claude, ChatGPT, Cursor and other assistants a real chemistry engine: they can convert structures, name them, work out their properties, draw them in a journal style, check them for mistakes and search Athanor’s library. It is free, needs no account, and stores nothing.

Try the name tool

This box calls the same server your assistant would, with the same name and depict tools.

Limits

  • 60 calls a minute from one address.
  • Structures up to 20,000 characters, as SMILES, a molfile, an InChI or a common name.
  • Every tool only reads what it is given and returns a result; nothing is kept.

Works with

ChatGPT, Claude, Claude Code, Codex CLI, Cursor, VS Code and Gemini CLI, and any client that supports remote MCP servers over Streamable HTTP.

Set it up in a minute

Athanor in your AI assistant

Claude, ChatGPT, Cursor and other assistants can use Athanor’s own chemistry engine through MCP: convert, name, draw and check structures, and run the safety screen. Free, with no account, and nothing stored.

Connect your assistant See the tools

The server

https://mcp-athanor.arbastro.com/mcp
  • convert SMILES, MOL and XYZ
  • name IUPAC and common names
  • properties formula, masses, descriptors
  • depict journal-style drawings
  • check valence, charge, stereo
  • screen the safety screen
  • library_search Athanor’s library

In Claude Code, one line

claude mcp add --transport http athanor https://mcp-athanor.arbastro.com/mcp

A real call: name on ibuprofen’s SMILES

Asking the server…