Generate and publish social posts with Gemini, Kie.ai, and Zernio API

Description

Quick overview
Generate & publish social media content with Gemini, Kie.ai, and Zernio API

How it works
Google Gemini (gemini-2.5-flash) generates platform-optimized copy for Facebook, Instagram, LinkedIn, and TikTok, returned as structured JSON with hashtags and a suggested posting time.
Kie.ai Seedream v4 creates a branded 1080x1080 image; the workflow polls the task until the CDN image URL is ready.
The image is uploaded to Zernio: direct multipart upload for files up to 4MB, presigned upload (init + PUT) for larger files up to 5GB.
A post is created on each enabled platform through the Zernio posts endpoint, with the correct platform and accountId mapping, and published immediately.
All platform responses are merged into one success report with ready-to-send messages for Slack, Discord, email, and webhook notifications.

Setup
Google Gemini (gemini-2.5-flash) generates platform-optimized copy for Facebook, Instagram, LinkedIn, and TikTok, returned as structured JSON with hashtags and a suggested posting time.
Kie.ai Seedream v4 creates a branded 1080x1080 image; the workflow polls the task until the CDN image URL is ready.
The image is uploaded to Zernio: direct multipart upload for files up to 4MB, presigned upload (init + PUT) for larger files up to 5GB.
A post is created on each enabled platform through the Zernio posts endpoint, with the correct platform and accountId mapping, and published immediately.
All platform responses are merged into one success report with ready-to-send messages for Slack, Discord, email, and webhook notifications.

Requirements
Google Gemini (gemini-2.5-flash) generates platform-optimized copy for Facebook, Instagram, LinkedIn, and TikTok, returned as structured JSON with hashtags and a suggested posting time.
Kie.ai Seedream v4 creates a branded 1080x1080 image; the workflow polls the task until the CDN image URL is ready.
The image is uploaded to Zernio: direct multipart upload for files up to 4MB, presigned upload (init + PUT) for larger files up to 5GB.
A post is created on each enabled platform through the Zernio posts endpoint, with the correct platform and accountId mapping, and published immediately.
All platform responses are merged into one success report with ready-to-send messages for Slack, Discord, email, and webhook notifications.

Customization
Edit the Gemini prompt to change tone, language, platform mix, or content structure
Swap the image model or prompt in the Kie.ai node
Replace publishNow with scheduledFor (ISO 8601 UTC) to schedule posts instead of publishing instantly
Wire the prepared notification payload into your own Slack, Discord, or email nodes
Swap the manual trigger for a Schedule or Webhook trigger for full autopilot

Additional info
Sticky notes inside the workflow document every section: overview, credentials, content generation, image generation, media upload, publishing logic, notifications, and error handling. Fallback content is included in case Gemini returns unparseable JSON. Estimated cost per run: about $0.02 for one Seedream image, a fraction of a cent for Gemini text, and no per-post cost from Zernio (usage-based pricing). Built by Adrian (RoboMarketing) for the n8n Arena Challenge, September 2025; updated for the Late to Zernio rebrand with the new presigned upload flow.