n8n Legal Proposal Automation: Google Sheets, GPT-4o & Gmail

Turn project requests into ready-to-send legal proposals—automatically

This n8n Legal Proposal Automation workflow takes a project intake via a POST webhook, looks up service pricing in Google Sheets, uses GPT-4o to analyze scope and generate a branded proposal, renders it to PDF and DOCX, and emails both attachments through Gmail.

What this workflow does

• Receives requests via Webhook: Accepts project requirements through a POST webhook and immediately returns a JSON acknowledgment.
• Pulls pricing from Google Sheets: Reads a service catalog and pricing table from Google Sheets and merges it with the submitted intake data.
• Analyzes scope with OpenAI: Uses gpt-4o-mini to propose phases, identify required services, and flag any missing services from the pricing catalog.
• Fills gaps with SerpApi (optional): When pricing is missing, queries SerpApi (Google search) and parses snippets to estimate market price ranges.
• Builds the full proposal output: Creates a cost breakdown, budget comparison, and timeline based on available pricing and the generated analysis.
• Generates branded HTML + documents: Uses gpt-4o to generate proposal HTML, applies branding, then renders to PDF via Gotenberg and converts to DOCX via a Pandoc-based HTTP endpoint.
• Sends via Gmail: Emails the HTML-derived PDF and DOCX as attachments using the Gmail integration.

Use cases

• SaaS operators or law-adjacent teams generating consistent proposals from form submissions.
• Automation engineers deploying an end-to-end proposal pipeline using n8n + Google Sheets pricing.
• Teams that need fast turnarounds when requested services don’t exist in the pricing catalog.

Technical details

• n8n nodes/tools: webhook, if, code, merge, sticky note, gmail.
• Integrations: Google Sheets (service pricing), OpenAI (gpt-4o-mini and gpt-4o), SerpApi (optional pricing estimation).
• Document rendering: Gotenberg for PDF; Pandoc-based HTTP service for DOCX conversion.

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