Generate Instagram Captions from Hashtag Analysis using Apify + GPT-4o-mini

This n8n workflow scrapes recent Instagram posts by hashtag and generates new, relevant caption ideas using OpenAI. It avoids making up suggestions by analyzing real-world content and surfacing common patterns.

✅ Use Case

Marketing teams, content creators, or social media managers can:

Discover what’s trending for a specific topic Automatically generate Instagram captions based on real posts Understand common caption styles for a niche Save time brainstorming ideas while staying on-brand

🧠 How It Works

1️⃣ Manual Trigger

🧩 Node: When clicking ‘Execute workflow’ Manually starts the workflow for testing or single-run execution.

2️⃣ Define the Hashtag

🧩 Node: Create Search Term Sets the value of the hashtag you'd like to scan. Default is n8n, but you can modify it to anything.

{ "Search_Term": "yourCustomHashtag" }

3️⃣ Scrape Instagram Posts

🧩 Node: Find Recent Posts API**: Apify Instagram Hashtag Scraper Setup**: Visit Apify Console Create an API token In n8n, go to Credentials and add HTTP Query Auth Use ?token=yourTokenHere as the query string

JSON Body: { "hashtags": ["{{ $json.Search_Term }}"], "resultsLimit": 20, "resultsType": "posts" }

4️⃣ Extract Captions

🧩 Node: Set bio and follower count Extracts just the caption from each post and stores it in a clean variable for the AI agent to use.

5️⃣ Aggregate Captions

🧩 Node: Aggregate Gathers all captions into one list before processing. Useful for passing a large text block into the AI.

6️⃣ Convert to Single Text Block

🧩 Node: Convert table names and columns into single text for agent Uses a Code node to combine all captions into a single string for OpenAI to read: return [ { json: { text: items .map(item => - ${JSON.stringify(item.json)}) .join('\n\n'), }, }, ];

7️⃣ Generate Caption Ideas with AI

🧩 Node: AI Agent Takes the combined post text and sends it to GPT-4o-mini. Includes this system message: I'm looking for ideas for posts about {{ $('Create Search Term').item.json.Search_Term }}. Here’s the last 5 posts on Instagram about the topic. Use those to help me generate a list of relevant captions.

Do not make up ideas that are not like the others in the list.

Output like this: { "Post Idea": ["Idea1", "Idea2"], "Most Common Post": ["common post 1", "common post 2"] }

8️⃣ Choose Language Model

🧩 Node: OpenAI Chat Model Model**: gpt-4o-mini Credential**: Use your OpenAI API key. Get it from: OpenAI API Keys Add it in n8n under OpenAI credentials.

9️⃣ Parse the AI Output

🧩 Node: Structured Output Parser Parses the GPT response into structured JSON: { "Post Idea": ["Idea1", "Idea2"], "Most Common Post": ["common post 1", "common post 2"] }

🔟 Split the Outputs

🧩 Nodes: Split Out, Split Out1 Separates the Post Idea list and Most Common Post list into individual items.

🔁 Merge for Final Output

🧩 Node: Merge Combines the two split lists into one output stream.

👤 Need More Help?

Robert Breen
Automation Consultant | AI Workflow Designer | n8n Expert
📧 robert@ynteractive.com
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