Instagram DM Reply Automation with ManyChat, ChatGPT Memory

Automate Instagram DM Replies with ManyChat + ChatGPT Memory

Stop drafting Instagram replies by hand. This n8n workflow receives your Instagram messages from ManyChat via webhook, uses OpenAI ChatGPT with session-based memory to keep conversations contextual, and sends a ready-to-send reply back to ManyChat—so your influencer-style DM automation stays fast and consistent.

What this workflow does

• Receives Instagram chat messages through a ManyChat Custom Action (external request) that POSTs to the workflow’s production webhook URL.
• Reads the message text and session_id from the incoming POST payload.
• Builds AI inputs by setting a system prompt (your Instagram voice and reply rules) and mapping the incoming message as the chat input.
• Loads recent conversation history for the same session using n8n buffer memory to maintain context across multiple DM turns.
• Generates a short, style-matched reply using the OpenAI ChatGPT node, including the system instructions plus memory context.
• Returns the generated response in the webhook response so ManyChat can deliver it back to Instagram.

Use cases

• Influencer or brand DM automation: respond to common questions while keeping replies consistent with your tone.
• Sales and lead qualification: maintain continuity across multiple messages using session_id memory.
• Support-style conversations: reference prior context so your Instagram DM responses don’t feel disconnected.

Technical details

• Webhook integration: n8n webhook receives POST requests from ManyChat.
• Data mapping: set nodes extract message text and session_id, and prepare AI inputs.
• AI reply generation: n8nn8n-nodes-langchainagent / n8nn8n-nodes-langchainlm chat open ai with an OpenAI ChatGPT credential.
• Session-based context: buffer memory keyed by the session ID for conversational continuity.
• Respond back: respond to webhook returns the AI-generated reply to ManyChat.

Setup note: In n8n, add your OpenAI API credential, select it in the OpenAI ChatGPT node, and edit the “Set your system promt for AI” step to match your Instagram voice. Optionally adjust the memory context window length to control how much chat history is used.