FastAPI Chatbot Blog
What is a Chatbot?
A chatbot is an application that allows users to communicate with a computer through messages. In an AI chatbot, an AI model understands the user's message and generates a suitable response.
What is a FastAPI Chatbot?
A FastAPI chatbot is a chatbot where FastAPI works as the backend. FastAPI receives the user's message, sends it to the Gemini AI API, receives the AI response, and returns it to the user.
Simple Architecture Flow:
USER → Enter the question("What is FastAPI?")→FastAPI→ Gemini API→Gemini AI→ return a answer ("FastAPI is a Python framework for APIs.")→ FastAPI→ USER
3. Technologies Used
Python →Programming language
FastAPI → Creates the backend API
Uvicorn — Runs the FastAPI server
Requests — Sends requests to Gemini
Gemini API — Provides AI responses
API Key — Allows FastAPI to access Gemini
4. How the Chatbot WorksStep 1: User enters a message.
Step 2: FastAPI receives the message.
Step 3: FastAPI creates a request for Gemini.
Step 4: The API key authenticates the request.
Step 5: Gemini understands the message.
Step 6: Gemini generates a response.
Step 7: FastAPI receives the response.
Step 8: FastAPI sends the response back to the user.
Example Chatbot Code
import requests
from fastapi import FastAPI
app = FastAPI()
API_KEY = "GEMINI_API_KEY"
@app.post("/chat")
def chat(message: str):
url = f"https://generativelanguage.googleapis.com/v1beta/models/gemini-3.5-flash:generateContent?key= {API_KEY}"
payload = {
"contents": [{
"parts": [{
"text": message
} ] } ] }
response = requests.post(url, json=payload)
data = response.json()
answer = data["candidates"][0]["content"]["parts"][0]["text"]
return {
"user_message": message,
"response": answer
}
Testing the Chatbot in FastAPI
Run the server:
uvicorn main:app --reload
Then open:
http://127.0.0.1:8000/docs
You will see:
POST /chat
Click Try it out, enter message, and click Execute.
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