I Built an AI Content API with 8 Endpoints for $0 - Here's How

#sideprojects #webdev #ai #api

I wanted a simple API for AI content tasks that returns clean JSON - not a chatbot, not a complex SDK. So I built ContentCraft AI and listed it on RapidAPI.

Here's what it does, how I built it, and what I learned.

What It Does

ContentCraft AI provides 8 POST endpoints for content creation:

Endpoint	What it does
/rewrite	Paraphrase text in 5 tones
/seo-analyze	SEO score, keyword density, suggestions
/headline-generate	Headlines in 5 styles
/summarize	Short/medium/long summaries
/email-generate	Marketing emails with subject + CTA
/social-post	Platform-optimized social posts
/extract-keywords	Keywords with relevance scores
/content-improve	Grammar, clarity, tone fixes

Every response is structured JSON. No markdown, no chat format.

Quick Example

curl -X POST "https://contentcraft-ai-green.vercel.app/api/v1/rewrite" \
  -H "X-RapidAPI-Key: YOUR_KEY" \
  -H "Content-Type: application/json" \
  -d '{"text": "Your text here", "tone": "professional"}'

Response:

{
  "original_length": 60,
  "rewritten_text": "Your professionally rewritten text...",
  "tone": "professional"
}

The Stack

Next.js 16 (App Router) on Vercel free tier
Google Gemini AI (free tier)
RapidAPI for auth, billing, and rate limiting
Zero database, zero Stripe, zero custom auth

Total cost: $0/month.

Why RapidAPI

RapidAPI handles the boring stuff - API keys, rate limiting, billing, and discovery. Developers already search for APIs there. I just build the endpoints and set the pricing.