Generate C API HTML docs from Google Drive headers with GPT-4o and Gmail

🚀 Overview

This n8n workflow automatically generates professional API documentation from C header (.h) files using AI.

It scans a Google Drive folder for header files, extracts the source code, sends it to GPT-4o for structured analysis, and generates a beautiful HTML documentation page. The final documentation is uploaded back to Google Drive and a completion email is sent.

This workflow is ideal for embedded systems teams, firmware engineers, and SDK developers who want an automated documentation pipeline.

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✨ Key Features

⚡ Fully automated documentation generation 📁 Reads .h files directly from Google Drive 🤖 Uses AI to analyze C APIs and extract documentation 📑 Generates clean HTML documentation 📊 Documents functions, types, enums, and constants 🔁 Processes files one-by-one for reliability ☁️ Saves generated documentation back to Google Drive 📧 Sends a completion email notification

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🧠 What the AI Extracts

The workflow automatically identifies and documents:

• 📘 Overview of the header file
• 🔧 Functions
• Signatures
• Parameters
• Return values
• Usage examples
• 🧩 Enumerations
• 🧱 Data Types & Structures
• 🔢 Constants / Macros
• 📝 Developer Notes

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🖥 Generated Documentation

The output is a clean developer-friendly HTML documentation page including:

• 🧭 Sidebar navigation
• 📌 Function cards
• 📊 Parameter tables
• 💻 Code examples
• 🎨 Professional developer layout

Perfect for:

• Developer portals
• SDK documentation
• Internal engineering documentation
• Embedded system libraries

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⚙️ Workflow Architecture

Step	Node	Purpose
1	▶️ Manual Trigger	Starts the workflow
2	📂 Get all files	Reads files from Google Drive
3	🔎 Filter .h files	Keeps only header files
4	🔁 Split in Batches	Processes files sequentially
5	⬇️ Download file	Downloads the header file
6	📖 Extract text	Extracts code content
7	🤖 AI Extraction	AI extracts API structure
8	🧹 Parse JSON	Cleans AI output
9	🎨 Generate HTML	Builds documentation page
10	☁️ Upload to Drive	Saves documentation
11	📧 Email notification	Sends completion email

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🔧 Requirements

To run this workflow you need:

🔹 Google Drive OAuth2 credentials 🔹 OpenAI API credentials 🔹 Gmail credentials

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🛠 Setup Guide

1️⃣ Configure Google Drive

Create two folders.

Source folder

Output folder

Update the folder IDs in the nodes:

• Get all files from folder
• Save documentation to Google Drive

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2️⃣ Configure OpenAI

Add an OpenAI credential in n8n.

Model used:

The model analyzes C header files and returns structured API documentation.

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3️⃣ Configure Gmail

Add a Gmail OAuth credential.

Update the recipient address inside:

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▶️ Run the Workflow

Click Execute Workflow.

The workflow will:

1️⃣ Scan the Google Drive folder 2️⃣ Process each .h file 3️⃣ Generate HTML documentation 4️⃣ Upload documentation to Drive 5️⃣ Send a completion email

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🖼 Documentation Preview

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💡 Use Cases

🔧 Embedded firmware documentation 📦 SDK documentation generation 🧑‍💻 Developer portal automation 📚 C library documentation ⚙️ Continuous documentation pipelines

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🔮 Future Improvements

This workflow can be extended with several enhancements:

📄 PDF Documentation Export

Add a step to convert the generated HTML documentation into PDF files using tools such as:

• Puppeteer
• HTML-to-PDF services
• n8n community PDF nodes

This allows teams to distribute documentation as downloadable reports.

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🔐 Local AI for Security (Ollama / Open-Source Models)

Instead of using the OpenAI node, the workflow can be modified to run fully locally using AI models such as:

• Ollama
• Open-source LLMs (Llama, Mistral, CodeLlama)

These models can run on your own server, which provides:

🔒 Better data privacy 🏢 No external API calls ⚡ Faster responses on local infrastructure 🛡 Increased security for proprietary source code

This can be implemented in n8n using:

• HTTP Request node → Ollama API
• Local AI inference servers
• Private LLM deployments

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📚 Multi-Language Documentation

The workflow could also support additional languages such as: .c .cpp .hpp .rs .go