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.

✨ 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

🧠 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

🖥 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

⚙️ 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 |

🔧 Requirements

To run this workflow you need:

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

🛠 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

2️⃣ Configure OpenAI

Add an OpenAI credential in n8n.

Model used:

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

3️⃣ Configure Gmail

Add a Gmail OAuth credential.

Update the recipient address inside:

▶️ 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

🖼 Documentation Preview

💡 Use Cases

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

🔮 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.

🔐 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

📚 Multi-Language Documentation

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