I kept Googling "X vs Y" and getting the same SEO-spam listicles
that say nothing useful. So I built Simily — type any two things
and get an actual AI-powered breakdown.
What it does
- Category-by-category scores (Performance, Price, Ease of Use, etc.)
- Pros & cons for each option
- A clear winner with reasoning
- FAQ section for common questions
- You can add up to 5 items to compare at once
Try it: ChatGPT vs Claude
The stack
Frontend: Next.js 16 App Router, Tailwind CSS v4, TypeScript
AI: Anthropic Claude API (claude-sonnet) — I send a structured
prompt and ask it to return JSON with scores, pros/cons, and FAQs.
Works surprisingly well.
Caching: Upstash Redis with a 7-day TTL. First person to run a
comparison pays the API cost, everyone after gets it instantly for free.
This keeps costs very low.
Deployment: Vercel
The interesting part — the prompt
Getting Claude to return consistent JSON was the main challenge.
The trick that worked was being very explicit about the schema and
adding a rule like "return only valid JSON, no markdown."
I also version the cache keys (compare:v3:...) so when I update
the prompt structure I can invalidate old cached responses without
touching Redis directly.
What I just added
- Best Of guides — ranked lists like Best AI Chatbot or Best Code Editor using the same AI engine
- Related comparisons — shows up to 6 "people also compare" links at the bottom of each page for internal linking
- Rate limiting — 10 requests per IP per hour using @upstash/ratelimit to protect the API budget
What's next
Working on getting more traffic via SEO — the 160+ pages in the
sitemap are slowly getting indexed by Google. Would love any feedback
on what's useful vs what's noise.
Check it out: simily.org
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