Get your Countersign key

One click gives you an API key + a ready-to-paste MCP config — the cross-vendor kill switch and spend guard inside Claude, Cursor, or any MCP client. Testnet sandbox; no funds, no signup form.

Your API key 

   
Store it now — it isn't shown again.

  
MCP config (Claude / Cursor) 

   
Or just run: npx @countersign/mcp with those env vars. Docs: @countersign/mcp