Sync CRM & Accounting via HTTP APIs + Google Sheets

Two-way CRM ↔ Accounting sync every 15 minutes—automatically resolves conflicts and logs them to Google Sheets

This n8n workflow keeps two HTTP API-based systems in sync (for example, a CRM and an accounting tool). It runs on a schedule, compares changes since the last successful run, resolves update conflicts using the newest updatedAt, and records any conflicts in Google Sheets for review.

What this workflow does

• Runs every 15 minutes using a Schedule Trigger.
• Calculates a sync window based on the last successful run time stored in the workflow’s static data.
• Fetches changed records from System A and System B via HTTP APIs (using configured “get changed records” endpoints).
• Matches records by externalId, so the same customer/contact/invoice can be updated across both systems.
• Skips updates that originated from the workflow itself (prevents endless sync loops).
• Auto-resolves conflicts when both sides changed: it chooses the record version with the latest updatedAt.
• Logs conflicts to Google Sheets with key details (including winner, timestamps, and resolution time) for human verification.
• Pushes updates via HTTP PUT to both systems and retries queued pushes that haven’t shown up yet.

Use cases

• Sync CRM contact/customer changes to an accounting system so records stay consistent without manual exports.
• Keep invoice- or customer-related updates aligned between two SaaS tools when both may be edited independently.
• Provide operational transparency by writing all conflict details to Google Sheets for auditing and dispute resolution.

Technical details

• Nodes/logic used: Schedule Trigger, HTTP Request, Code, Google Sheets, and conditional logic (if).
• Requires both systems to expose externalId for matching and updatedAt for conflict resolution (or update field names in the code).
• Setup includes configuring HTTP header authentication, replacing placeholder API URLs (e.g., YOUR_SYSTEM_A_API / YOUR_SYSTEM_B_API), and adding Google Sheets credentials.