Automate monthly Google Ads performance analysis with GPT-4o, Sheets & Slack

📊 Google Ads + OpenAI + Sheets — Monthly AI Performance Analysis

Automate monthly ad performance insights with AI-powered recommendations

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🧩 Overview

This workflow automatically analyzes Google Ads performance every month, using the Google Ads API and OpenAI (GPT-4o) to uncover which ad themes, categories, and messages perform best. It then generates a structured AI report, saves it to Google Sheets, and sends a Slack summary to your marketing team.

💡 Perfect for digital marketers, agencies, and growth analysts who want automated campaign insights without manually crunching numbers.

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⚙️ Features

✅ Automatically runs on the 1st of each month ✅ Fetches last 30 days of ad performance via Google Ads API (GAQL) ✅ Uses GPT-4o for natural-language insights & improvement ideas ✅ Groups ads by category and theme (e.g., “Free Shipping,” “Premium”) ✅ Generates a clean, formatted markdown report ✅ Archives reports in Google Sheets for trend tracking ✅ Notifies your Slack channel with AI-driven recommendations

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🧠 Architecture

Component	Purpose
n8n	Workflow engine
Google Ads API	Source of ad performance data
OpenAI (GPT-4o)	Analyzes CTR patterns and writes recommendations
Google Sheets	Report archiving and history tracking
Slack	Team notifications

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🧭 Workflow Logic (Summary)

Monthly Trigger (1st of Month) ⬇️ 1️⃣ Get Performance Data (Google Ads API) Fetches 30-day CTR, clicks, impressions for all responsive search ads. ⬇️ 2️⃣ Prepare Performance Data Groups data by ad group and theme keywords, builds an AI prompt. ⬇️ 3️⃣ AI Agent (LangChain) + GPT-4o Analyzes patterns and generates actionable insights. ⬇️ 4️⃣ Generate Report (Code) Formats a Markdown report with AI recommendations and KPIs. ⬇️ 5️⃣ Save to Google Sheets Archives results for long-term analytics. ⬇️ 6️⃣ Send Report to Slack Delivers the summary directly to your marketing channel.

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🔑 Environment Variables

Variable	Example	Description
GOOGLE_ADS_CUSTOMER_ID	123-456-7890	Google Ads customer account ID
GOOGLE_ADS_API_VERSION	v17	Current Ads API version
GOOGLE_SHEET_ID	1xA1B2c3D4EFgH...	Target spreadsheet ID
OPENAI_API_KEY	sk-xxxxx	OpenAI API key for GPT-4o
SLACK_WEBHOOK_URL	https://hooks.slack.com/...	Slack incoming webhook

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🔐 Credential Setup

Service	Type	Required Scopes
Google Ads	OAuth2 (googleAdsOAuth2Api)	https://www.googleapis.com/auth/adwords
OpenAI	API key (openAiApi)	Full access
Google Sheets	OAuth2	https://www.googleapis.com/auth/spreadsheets
Slack	Webhook	chat:write

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🧱 Node-by-Node Breakdown

Node	Purpose	Key Configuration
Monthly Trigger	Starts workflow on 1st of every month	Cron: 0 0 1 * *
Get Performance Data	Queries Ads data	Endpoint: https://googleads.googleapis.com/v17/customers/{id}/googleAds:search Query: GAQL (CTR, clicks, impressions, last 30 days)
Prepare Performance Data	Aggregates and builds AI prompt	Groups by ad group and theme, computes CTRs
AI Agent – Analyze Performance	Passes formatted data to GPT-4o	System message: “You are a Google Ads performance analyst…”
OpenAI Chat Model (GPT-4o)	Analytical reasoning engine	Model: gpt-4o, Temperature 0.2
Generate Report	Parses AI output, formats Markdown report	Adds recommendations + next steps
Save Report to Sheets	Archives report	Sheet name: Performance Reports
Send Report (Slack)	Sends summary	Uses report_markdown variable

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🧠 AI Report Example

# 30-Day Performance Analysis Report

## Executive Summary
Analyzed: 940 ads
Period: Last 30 days

## Top Performing Categories
- Running Shoes: 9.4% CTR (120 ads)
- Fitness Apparel: 8.2% CTR (90 ads)

## Top Performing Themes
- "Free Shipping" messaging: 9.8% CTR (58 ads)
- "Premium" messaging: 8.5% CTR (44 ads)

## AI-Powered Recommendations
1. [HIGH] Emphasize “Free Shipping” across more ad groups.  
   Expected Impact: +5 % CTR  
2. [MEDIUM] Test “Premium Quality” vs. “New Arrivals.”  
   Expected Impact: +3 % CTR  

## Next Steps
1. Implement new ad variations  
2. A/B test messaging  
3. Re-analyze next month

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🧩 Testing Procedure

1️⃣ Temporarily disable the cron trigger. 2️⃣ Run the workflow manually. 3️⃣ Confirm:

• Google Ads node returns JSON with results.
• AI Agent output is valid JSON.
• Report is written to Sheets.
• Slack message received.

4️⃣ Re-enable the monthly trigger once verified.

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🧾 Output in Google Sheets

Date	Ads Analyzed	Top Category	Top Theme	Key Recommendations	Generated At
2025-10-01	940	Running Shoes	Free Shipping	“Add Free Shipping copy to 10 ads”	2025-10-01T00:05Z

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🪜 Maintenance

Frequency	Task
Monthly	Review AI accuracy and update themes list
Quarterly	Refresh Google Ads API credentials
As needed	Update GAQL fields for new metrics

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⚙️ API Verification

Endpoint: POST https://googleads.googleapis.com/v17/customers/{customer_id}/googleAds:search

Scopes: https://www.googleapis.com/auth/adwords

GAQL Query:

SELECT ad_group_ad.ad.id,
       ad_group_ad.ad.responsive_search_ad.headlines,
       ad_group.name,
       metrics.impressions,
       metrics.clicks,
       metrics.ctr
FROM ad_group_ad
WHERE segments.date DURING LAST_30_DAYS
  AND metrics.impressions > 100
ORDER BY metrics.clicks DESC
LIMIT 1000

✅ Fully valid query — verified for GAQL syntax, fields, and resource joins. ✅ OAuth2 flow handled by n8n’s googleAdsOAuth2Api. ✅ Optional: add "timeout": 60000 for large accounts.

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📈 Metrics of Success

KPI	Target
Report accuracy	≥ 95 %
Monthly automation success	≥ 99 %
CTR improvement tracking	+3–5 % over time

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🔗 References

• Google Ads API Docs
• LangChain in n8n
• OpenAI API Reference
• Google Sheets API
• Slack Incoming Webhooks

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🎯 Conclusion

You now have a fully automated Google Ads performance analysis workflow powered by:

• Google Ads API for granular metrics
• OpenAI GPT-4o for intelligent recommendations
• Google Sheets for archiving
• Slack for team-wide updates

💡 Result: A recurring, data-driven optimization loop that improves ad performance every month — with zero manual effort.