AI Copywriter App Template: Build a Content Generation Platform

AI-powered content generation is one of the fastest-growing SaaS categories in 2026. From blog posts and social media copy to product descriptions and email campaigns, businesses are adopting AI copywriting tools at an accelerating rate. Building an AI copywriter app requires integrating LLM APIs, managing prompt templates, handling streaming responses, and implementing usage-based billing.

An AI copywriter app template provides all of this infrastructure so you can launch your content generation platform in days.

Core Features of an AI Copywriter Platform

A production-ready AI content generation app includes:

• Multiple content types (blog posts, social media, emails, ads)
• Prompt template management with variables
• Tone and style customization
• Streaming response generation
• Content history and saved drafts
• Team collaboration features
• Usage-based billing with Stripe
• Brand voice profiles

The AI Copywriter template includes all of these features pre-built.

Prompt Template System

// lib/ai/templates.ts
export const promptTemplates = {
  blogPost: {
    name: 'Blog Post',
    prompt: 'Write a {tone} blog post about {topic}. Target audience: {audience}. Length: {length} words. Include an introduction, {sections} sections, and a conclusion.',
    variables: ['tone', 'topic', 'audience', 'length', 'sections'],
  },
  socialMedia: {
    name: 'Social Media Post',
    prompt: 'Create a {platform} post about {topic}. Tone: {tone}. Include relevant hashtags and a call to action.',
    variables: ['platform', 'topic', 'tone'],
  },
  emailCampaign: {
    name: 'Email Campaign',
    prompt: 'Write a {type} email for {audience}. Subject line should be catchy. The email should promote {offer} and include a clear CTA.',
    variables: ['type', 'audience', 'offer'],
  },
}

export type TemplateKey = keyof typeof promptTemplates

export function fillTemplate(key: TemplateKey, variables: Record<string, string>) {
  let prompt = promptTemplates[key].prompt
  for (const [k, v] of Object.entries(variables)) {
    prompt = prompt.replace(`{${k}}`, v)
  }
  return prompt
}

Content Generation API

// app/api/generate/route.ts
import OpenAI from 'openai'
import { OpenAIStream, StreamingTextResponse } from 'ai'
import { auth } from '@/lib/auth'
import { checkSubscriptionAccess } from '@/lib/stripe/access'

const openai = new OpenAI({ apiKey: process.env.OPENAI_API_KEY! })

export async function POST(req: Request) {
  const session = await auth()
  if (!session?.user) return new Response('Unauthorized', { status: 401 })

  const hasAccess = await checkSubscriptionAccess(session.user.id)
  if (!hasAccess) return new Response('Upgrade required', { status: 403 })

  const { prompt, tone, length } = await req.json()

  const systemPrompt = `You are a professional copywriter. Write in a ${tone} tone.
  Aim for approximately ${length} words. Use clear, engaging language.`

  const response = await openai.chat.completions.create({
    model: 'gpt-4o',
    stream: true,
    messages: [
      { role: 'system', content: systemPrompt },
      { role: 'user', content: prompt },
    ],
  })

  const stream = OpenAIStream(response)
  return new StreamingTextResponse(stream)
}

Content Editor Component

'use client'

import { useState } from 'react'
import { useCompletion } from 'ai/react'

export function ContentEditor() {
  const [topic, setTopic] = useState('')
  const [tone, setTone] = useState('professional')
  const [template, setTemplate] = useState('blogPost')

  const { completion, complete, isLoading } = useCompletion({
    api: '/api/generate',
  })

  const handleGenerate = () => {
    complete('', {
      body: {
        prompt: `Write a ${tone} blog post about ${topic}`,
        tone,
        length: 1000,
      },
    })
  }

  return (
    <div className="grid gap-8 lg:grid-cols-2">
      <div className="space-y-4">
        <input
          type="text"
          value={topic}
          onChange={e => setTopic(e.target.value)}
          placeholder="Enter your topic..."
          className="w-full rounded-xl border px-4 py-3"
        />
        <select
          value={tone}
          onChange={e => setTone(e.target.value)}
          className="w-full rounded-xl border px-4 py-3"
        >
          <option value="professional">Professional</option>
          <option value="casual">Casual</option>
          <option value="humorous">Humorous</option>
          <option value="authoritative">Authoritative</option>
        </select>
        <button
          onClick={handleGenerate}
          disabled={isLoading || !topic}
          className="w-full rounded-xl bg-brand-600 py-3 font-semibold text-white disabled:opacity-50"
        >
          {isLoading ? 'Generating...' : 'Generate Content'}
        </button>
      </div>
      <div className="rounded-xl border bg-white p-6 min-h-[300px]">
        {completion || 'Your generated content will appear here...'}
      </div>
    </div>
  )
}

Launch your AI content platform with the AI Copywriter App Template and start generating content in days.

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