How I built a $0/mo AI SaaS using Next.js 14 and Google Gemini

Source: Dev.to

Introduction

I wanted to build an AI tool without paying the $20/month fee for OpenAI. This post explains how I created a Client Email Generator using Google’s free Gemini Flash model and Vercel.

Tech Stack

• Next.js 14 (App Router)
• Tailwind CSS (for the Agency UI)
• Google Gemini API
• Resend (for emailing)

Implementation

API Route

import { NextResponse } from 'next/server';
const genAI = new GoogleGenerativeAI(process.env.GEMINI_API_KEY || "");

export async function POST(request: Request) {
  const model = genAI.getGenerativeModel({ model: "gemini-2.5-flash" });

  const prompt = `Rewrite this technical Jira ticket for a non-technical client: ${ticketText}`;

  const result = await model.generateContent(prompt);
  const response = await result.response;
  const rewrittenText = response.text();

  return NextResponse.json({ rewrittenText });
} catch (error: any) {
  // error handling logic here
}

UI Design

I used a “Navy & Teal” theme to give the interface a professional look.

Result

The generator works perfectly: paste a Jira ticket and receive a client‑ready email instantly.

Source Code

The complete project (source code, repository, and setup guide) is available as a Starter Kit for anyone who wants to launch their own AI SaaS.

View the Starter Kit on IndieMaker