How to Build a Resume Builder SaaS in 2025 (Complete Guide)

┌─────────────────────────────────────────────────────────┐
│                    Frontend (Next.js)                    │
├──────────────┬──────────────┬──────────────┬────────────┤
│   Template   │    Resume    │     User     │  Payment   │
│   Gallery    │    Editor    │   Dashboard  │   Pages    │
└──────────────┴──────────────┴──────────────┴────────────┘
                              │
                              ▼
┌─────────────────────────────────────────────────────────┐
│                   API Layer (Next.js API)                │
├──────────────┬──────────────┬──────────────┬────────────┤
│   /resume    │  /templates  │    /user     │  /payment  │
│    CRUD      │    fetch     │    auth      │   stripe   │
└──────────────┴──────────────┴──────────────┴────────────┘
                              │
                              ▼
┌─────────────────────────────────────────────────────────┐
│                  Services Layer                          │
├──────────────┬──────────────┬──────────────┬────────────┤
│     PDF      │      AI      │    Email     │  Storage   │
│  Generator   │   Parser     │   Service    │  (S3/R2)   │
└──────────────┴──────────────┴──────────────┴────────────┘
                              │
                              ▼
┌─────────────────────────────────────────────────────────┐
│              Database (PostgreSQL + Prisma)              │
├──────────────┬──────────────┬──────────────┬────────────┤
│    Users     │   Resumes    │  Templates   │ Payments   │
└──────────────┴──────────────┴──────────────┴────────────┘

// Prisma Schema (simplified)
model User {
  id        String   @id @default(cuid())
  email     String   @unique
  name      String?
  resumes   Resume[]
  plan      Plan     @default(FREE)
  createdAt DateTime @default(now())
}

model Resume {
  id         String   @id @default(cuid())
  userId     String
  user       User     @relation(fields: [userId])
  templateId String
  data       Json     // Resume content
  title      String
  isPublic   Boolean  @default(false)
  createdAt  DateTime @default(now())
  updatedAt  DateTime @updatedAt
}

model Template {
  id          String  @id @default(cuid())
  name        String
  thumbnail   String
  category    String  // professional, creative, simple
  isPremium   Boolean @default(false)
  styles      Json    // Template-specific styling
}

// types/resume.ts
interface ResumeData {
  personalInfo: {
    fullName: string;
    email: string;
    phone: string;
    location: string;
    linkedin?: string;
    website?: string;
    summary: string;
  };
  experience: {
    company: string;
    position: string;
    startDate: string;
    endDate: string;
    current: boolean;
    description: string;
    highlights: string[];
  }[];
  education: {
    institution: string;
    degree: string;
    field: string;
    graduationDate: string;
    gpa?: string;
  }[];
  skills: {
    category: string;
    items: string[];
  }[];
  certifications?: {...}[];
  projects?: {...}[];
}

// Template component
const ProfessionalTemplate: FC<{ data: ResumeData }> = ({ data }) => {
  return (
    <div className="resume-page a4-size">
      <Header personalInfo={data.personalInfo} />
      <Summary text={data.personalInfo.summary} />
      <ExperienceSection items={data.experience} />
      <EducationSection items={data.education} />
      <SkillsSection skills={data.skills} />
    </div>
  );
};

// lib/pdf-generator.ts
import puppeteer from 'puppeteer';

export async function generateResumePDF(
  html: string,
  options: { format?: 'A4' | 'Letter' } = {}
): Promise<Buffer> {
  const browser = await puppeteer.launch({
    headless: 'new',
    args: ['--no-sandbox', '--disable-setuid-sandbox']
  });

  try {
    const page = await browser.newPage();

    // Set content and wait for fonts
    await page.setContent(html, {
      waitUntil: 'networkidle0'
    });

    // Generate PDF with proper margins
    const pdf = await page.pdf({
      format: options.format || 'A4',
      printBackground: true,
      margin: {
        top: '0.5in',
        right: '0.5in',
        bottom: '0.5in',
        left: '0.5in'
      }
    });

    return Buffer.from(pdf);
  } finally {
    await browser.close();
  }
}

// Using Google Gemini for resume parsing
import { GoogleGenerativeAI } from '@google/generative-ai';

const genAI = new GoogleGenerativeAI(process.env.GEMINI_API_KEY);

async function parseResume(fileBuffer: Buffer, mimeType: string) {
  const model = genAI.getGenerativeModel({
    model: 'gemini-1.5-pro'
  });

  const prompt = `
    Extract all information from this resume into JSON format:
    {
      "personalInfo": { "fullName", "email", "phone", ... },
      "experience": [...],
      "education": [...],
      "skills": [...]
    }
    Be thorough and extract ALL information.
  `;

  const result = await model.generateContent([
    prompt,
    {
      inlineData: {
        mimeType,
        data: fileBuffer.toString('base64')
      }
    }
  ]);

  return JSON.parse(result.response.text());
}