MCP servers · Lemlist · connector · GPT action
Connect ChatGPT to Lemlist
One line gives ChatGPT your Lemlist account as tools: 7 endpoints, campaigns, activities, leads, called with your own connection. No key in the prompt, a receipt for every call, revoke ChatGPT's access alone any time.
Three steps
- Create a free 0n3 account and connect Lemlist. Paste a key or sign in; it lands in your vault, encrypted.
- Install 0n3 into ChatGPT. A custom connector in Developer mode, or an Action on a custom GPT from the OpenAPI spec.
- Ask ChatGPT: whoami. Then: "List campaigns in Lemlist".
Custom connector (needs Developer mode)
- Settings → Connectors (or Apps) → Advanced → Developer mode on
- Create → name 0n3 · MCP server URL https://0n3.app/mcp · Authentication: OAuth
- Finish the sign-in with your 0n account
- Enable the connector in a chat and ask: "whoami"
ChatGPT connectors cannot send a static header, so 0n3 signs you in through its OAuth door (dynamic client registration is on).
The line above carries a placeholder; 0n3.app/install mints a real key named for ChatGPT and fills it in.
What ChatGPT can then do in Lemlist
Campaigns · Manage outreach campaigns5
List campaigns
GET /campaignsGet a campaign
GET /campaigns/{campaignId}Add a lead
POST /campaigns/{campaignId}/leads/{email}List leads
GET /campaigns/{campaignId}/leadsDelete a lead
DELETE /campaigns/{campaignId}/leads/{email}Activities · Track email activities1
List activities
GET /activitiesLeads · Manage campaign leads0
Manage campaign leads
More · Everything else this app exposes.1
Get a team
GET /teamLemlist in other AI clients
Claude Code + LemlistMCP server + skillClaude (desktop & claude.ai) + LemlistconnectorCodex CLI + LemlistMCP serverGemini CLI + LemlistMCP serverCursor + LemlistMCP serverVS Code (Copilot) + LemlistMCP serverWindsurf + LemlistMCP server