AI Vision Chat API (Go)

Production-style demo API that accepts text + image uploads and routes them to:

• local multimodal inference via Ollama
• cloud vision models via OpenAI and Google Gemini

This project is designed as a portfolio backend sample focused on API design, multipart handling, provider abstraction, and secure environment-based configuration.

Why this project

• Demonstrates practical Go backend skills with Gin routing and handler separation
• Shows multimodel AI integration in one service (Ollama, OpenAI, Gemini)
• Includes DTO/service layering to keep request/response logic organized
• Uses env vars for credentials (no hardcoded API keys)

Tech Stack

• Go 1.20+
• Gin (github.com/gin-gonic/gin)
• OpenAI Chat Completions (vision request format)
• Google GenAI SDK (google.golang.org/genai)
• Ollama local API (http://localhost:11434)

Project Structure

cmd/
  main.go                 # app entrypoint and route registration
internal/
  dto/                    # request/response models
  service/                # OpenAI, Gemini, image utilities
web/
  app/
    chat_app.go           # HTTP handlers

API Endpoints

Base URL: http://localhost:8089/api/v1

• GET /responses
  • Health-style sample chatbot response
• GET /responses/version
  • Proxies Ollama tag/version info
• POST /responses
  • Local Ollama multimodal chat
  • Multipart fields: message, file
• POST /openai/vision
  • OpenAI vision analysis
  • Multipart fields: message, file
• POST /google/vision
  • Gemini-based product extraction flow
  • Multipart fields: message, data

Quick Start

1. Clone and enter the repo.
2. Copy environment template.
3. Run the server.

cp .env.example .env
go run ./cmd

Server listens on :8089.

Configuration

Set values in .env (or export in your shell):

• OPENAI_API_KEY for POST /api/v1/openai/vision
• GEMINI_API_KEY for POST /api/v1/google/vision

Template file: .env.example

Example Requests

OpenAI vision

curl -X POST "http://localhost:8089/api/v1/openai/vision" \
  -F "message=Describe what you see" \
  -F "file=@/absolute/path/to/image.jpg"

Gemini vision

curl -X POST "http://localhost:8089/api/v1/google/vision" \
  -F "message=Extract product details" \
  -F "data=@/absolute/path/to/image.jpg"

Ollama local vision

curl -X POST "http://localhost:8089/api/v1/responses" \
  -F "message=What is in this image?" \
  -F "file=@/absolute/path/to/image.jpg"

Security Notes

• Do not commit .env.
• Keep API keys in environment variables only.
• .gitignore is configured to ignore .env and .env.* (except .env.example).

Portfolio Highlights

• Multipart upload handling and file persistence
• External API orchestration with structured error handling
• Model output normalization into typed DTO responses
• Clear path to evolve into provider interface abstraction and tests per provider

License

MIT - see LICENSE.