Generate LinkedIn carousel images from text with Mistral AI & S3 Storage

AI Carousel Caption & Template Editor Workflow

Overview

This workflow is a caption-only carousel text generator built in n8n. It turns any raw LinkedIn post or text input into 3 short, slide-ready title + subtext captions and renders those captions onto image templates. Output is a single aggregated response with markdown image embeds and download links.

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Workflow Structure

• Input: Chat UI trigger accepts text and optional template selection.
• Core AI: Agent cleans input and returns structured JSON with 3 caption pairs.
• Template Rendering: Edit Image nodes render title and subtext on chosen templates.
• Storage: Rendered images uploaded to S3.
• Aggregate Output: Aggregate node builds final markdown response with embeds and download links.

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Chat Trigger (Frontend)

• Trigger: When chat message received
  • UI accepts plain text post.
  • allowFileUploads optional for template images.
  • SessionId preserved for context.

AI Agent (Core)

• Node name: AI Agent
• Model: Mistral Cloud Chat Model (mistral-small-latest)
• Behavior:
  • Clean input (remove stray formatting like \n and ** but keep emojis).
  • Produce exactly one JSON object with fields: postclean, title1, subtext1, title2, subtext2, title3, subtext3.
  • Titles must be short (max 5 words). Subtext 1 or 2 short sentences, max 7 words per line if possible.
  • Agent must return valid JSON to be parsed by the Structured Output Parser.

Structured Output Parser

• Node name: Structured Output Parser
• Validates agent JSON and prevents downstream errors. If parsing fails, stop and surface error.

Normalize Title Nodes

• Nodes: normalize title,name 1, normalize title,name 2, normalize title,name 3 (and optional 4)
• Map parsed output into node fields: title, subtext, safeName (safe filename for exports).

Template Images

• Source: Google Drive template PNGs (download via Google Drive nodes) or provided upload.
• Keep templates high resolution and consistent aspect ratio.

Edit Image Nodes (Render Captions)

• Nodes: Edit Image 1, Edit Image2, Edit Image3, Edit Image3 (or Edit Image3/Edit Image4 as available)
• MultiStep operations render:
  • Title text (font, size, position)
  • Subtext (font, size, position)
• This is where caption text is added to the template.

Upload to S3

• Nodes: S3
• Upload rendered images to bucketname using safeName filenames. Confirm public access or use signed URLs.

Get S3 URLs and Aggregate

• Nodes: get s3 url image 1, get s3 url image 2, get s3 url image 3, get s3 url image 4
• Merge + Aggregate: Merge1 and Aggregate collect image items.
• Output Format: output format builds a single markdown message:
  • Inline image embeds ![image](<s3-url>)
  • Download links per image.

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Integrations Used

Service	Purpose	Credential
Mistral Cloud	AI agent model	Mistral account
Google Drive	Template image storage	Google Drive account
S3	Store rendered images and serve links	Supabase account
n8n Core	Flow control, parsing, image editing	Native

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Agent System Prompt Summary

> You are a data formatter and banner caption creator. Clean the user input (remove stray newlines and markup but keep emojis). Return a single JSON object with postclean, title1/subtext1, title2/subtext2, title3/subtext3. Titles must be short (max 5 words). Subtext should be 1 to 2 short sentences, useful and value adding. Respond only with JSON.

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Key Features

• Caption only output: 3 short slide-ready caption pairs.
• Structured JSON output enforced by a parser for reliability.
• Renders captions onto image templates using Edit Image nodes.
• Uploads images to S3 and returns markdown embeds plus download links.
• Template editable: swap Google Drive background templates or upload your own.
• Zero guess formatting: agent must produce parseable JSON to avoid downstream failures.

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Summary

A compact n8n workflow that converts raw LinkedIn text into a caption-only carousel with rendered images. It enforces tight caption rules, validates AI JSON, places captions on templates, uploads images, and returns a single ready-to-post markdown payload.

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Need Help or More Workflows?

We can wire this into your account, replace templates, or customize fonts, positions, and export options.
We can help you set it up for free — from connecting credentials to deploying it live.

Contact: [email protected]
Website: https://www.digitalbiz.tech
LinkedIn: https://www.linkedin.com/company/digital-biz-tech/
You can also DM us on LinkedIn for any help.