Who is this for?

Anyone curating before/after text examples in a spreadsheet and wanting a push-button path to a fine-tuned GPT model—without touching curl. Works with Google Sheets or Airtable.

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What problem does it solve?

Manually downloading CSVs, converting to JSONL, uploading, and polling OpenAI is a slog.
This flow automates the whole loop: grab examples flagged Ready, build the JSONL file, start the fine-tune, then log the resulting model ID back to a registry sheet/table for reuse.

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How it works

| # | Node | Purpose | |---|------|---------| | 1 | Schedule Trigger | Runs weekly by default (change as needed). | | 2a | Get Examples from Sheet | Pulls rows where Ready = TRUE from your Google Sheet. Uses the JSONL-Template Sheet as the expected column layout. | | 2b | Get Examples from Airtable (disabled) | Alternate source for Airtable users. | | 3 | Create JSONL File (Code) | Converts each example to chat-format JSONL and splits into train.jsonl / val.jsonl (80/20). | | 4 | Upload JSONL | Uploads the training file to OpenAI (purpose: fine-tune). | | 5 | Begin Fine-Tune | Starts a fine-tune job on gpt-4o (editable). | | 6 | Wait → Check Job → IF | Polls every minute until status = succeeded. | | 7a | Write Model to Sheet | Appends the new model ID + meta to your Model Registry sheet. | | 7b | Write Model to Airtable (disabled) | Equivalent logging step for Airtable. |

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Setup steps

1. Import & connect credentials

   • Import the JSON flow into n8n.
   • Add your OpenAI API key.
   • Google Sheets: create an OAuth2 credential and link it to both Sheets nodes.
   • Airtable (optional): create a Personal Access Token and attach it to the Airtable nodes.

2. Copy the template sheet

   • Duplicate the JSONL-Template Sheet linked above into your own Drive.
   • Required columns (exact names):
     | systemPrompt | userPrompt | assistantResponse | Ready |
   • Tick Ready = TRUE for rows you want to include.

3. Create the registry sheet/table

   • Google Sheet (or Airtable table) named Model Registry with columns:
     Model ID, Training Examples, Epochs, Batch Size, Learning Rate, Finished At.

4. Tweak model & schedule

   • Change the base model in Begin Fine-Tune if desired.
   • Adjust the Schedule Trigger for daily / on-demand runs.

5. Test it

   • Mark a few examples Ready = TRUE.
   • Run the flow manually.
   • Check OpenAI for the new fine-tune job and confirm the model ID is logged in your registry.

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Resources

• n8n Docs – https://docs.n8n.io/
• OpenAI Fine-Tuning – https://platform.openai.com/docs/guides/fine-tuning
• Google Sheets API – https://developers.google.com/sheets/api
• Airtable API – https://airtable.com/api

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Extending the flow

• Webhook trigger – swap the schedule for a webhook to train on demand.
• Multi-source merge – enable both Sheets and Airtable nodes to combine datasets.
• Auto-deploy – save the new model name to an env-var or Secrets Manager for downstream generation workflows.