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AI-powered astrology compatibility from real birth charts

ChartChemistry uses Swiss Ephemeris astronomical data and Claude AI to calculate real natal chart compatibility. Enter two birth details and get a detailed synastry report covering emotional, intellectual, physical, and spiritual connection — not just sun sign matching. Free tier available, premium reports go deep.

Astrology, Artificial Intelligence, Relationships, Dating

Hey PH! I'm Kay, the maker of ChartChemistry.

Most astrology apps stop at sun signs. We use Swiss Ephemeris (the same engine professional astrologers use) to calculate exact planetary positions from your birth time and location, then Claude AI interprets the synastry between two charts.

What makes it different:
- Real astronomical calculations, not generic horoscope matching
- Analyzes all planets, houses, and aspects between two charts
- Claude AI writes personalized compatibility narratives
- Free tier gives you a solid overview; premium goes much deeper

Built with Next.js, Python FastAPI, and a lot of late nights. Would love your feedback!

ChartChemistry

https://chartchemistry.com

AI-powered astrology compatibility using real birth chart calculations

ChartChemistry calculates real astrological compatibility using Swiss Ephemeris for precise planetary positions and Claude AI for personalized interpretations. Enter two birth details — date, time, and location — and get a detailed synastry report analyzing emotional bonds, intellectual connection, physical chemistry, and long-term potential. Goes beyond sun sign matching to examine all planetary aspects, house overlays, and composite patterns. Free tier available with premium deep-dive reports.

ChartChemistry

https://chartchemistry.com

Astrology / Relationships

ChartChemistry is an AI-powered astrology compatibility tool that uses Swiss Ephemeris for real astronomical calculations and Claude AI for personalized chart interpretations. It calculates natal charts from exact birth data (date, time, location), then analyzes synastry between two people — covering planetary aspects, house overlays, composite charts, and element balance. Reports are written in natural language by AI, covering emotional, intellectual, physical, and spiritual compatibility. Free compatibility overview available; premium reports include 20+ page deep-dive analysis.

Lifestyle / Relationships

ChartChemistry combines professional-grade astronomical calculations (Swiss Ephemeris) with AI interpretation (Claude) to deliver real astrology compatibility reports. Unlike generic sun sign apps, it uses exact birth time and location to calculate precise planetary positions, then analyzes the synastry between two natal charts.

- Real natal chart calculations using Swiss Ephemeris
- AI-written compatibility reports powered by Claude
- Synastry analysis: planetary aspects, house overlays, composite charts
- Covers emotional, intellectual, physical, and spiritual compatibility
- Element and modality balance scoring
- Personal astrologer chat (Marie) for premium users
- Daily cosmic weather and horoscopes
- Shareable cosmic identity cards and story cards
- Monthly cosmic events calendar
- 78 zodiac pair compatibility pages

Free: Basic compatibility overview, daily cosmic weather, natal chart viewer
Premium ($9.99/mo): Full deep-dive reports, Marie AI chat, daily digest emails
Annual ($79.99/yr): All premium features, best value
Single Report ($4.99): One-time purchase for a full compatibility report

Astrology / Lifestyle / AI Tools

ChartChemistry is an AI-powered astrology compatibility platform that calculates real synastry from birth chart data using Swiss Ephemeris and generates personalized reports with Claude AI. It goes beyond sun sign matching — analyzing planetary aspects, house overlays, composite charts, and element balance to give couples and friends a detailed compatibility breakdown. Includes a personal AI astrologer (Marie), daily cosmic weather, natal chart viewer with animated SVG wheel, and shareable social cards.

Co-Star, The Pattern, Sanctuary Astrology

Unlike Co-Star (which focuses on daily push notifications) or The Pattern (which uses its own non-traditional system), ChartChemistry focuses specifically on compatibility analysis using standard Western astrology with Swiss Ephemeris precision. Reports are AI-generated narratives rather than templated text, and the free tier provides a real compatibility analysis — not just a teaser.

ChartChemistry is an AI astrology compatibility app I built as a solo developer. It uses Swiss Ephemeris (the gold standard for astronomical calculations) to compute real natal charts, then Claude AI writes personalized compatibility reports based on synastry analysis.

The app covers the full astrology workflow: natal chart generation with an animated SVG wheel, compatibility scoring across emotional/intellectual/physical/spiritual dimensions, a personal AI astrologer chat (Marie), daily horoscopes, and shareable social cards for Instagram/TikTok.

Next.js 16 (App Router, React 19, TypeScript), Python FastAPI microservice (Swiss Ephemeris), Claude AI (reports) + GPT-4.1 Nano (chat/horoscopes), PostgreSQL (Supabase) via Prisma, Stripe (subscriptions + one-time purchases), Tailwind CSS + Framer Motion, Vercel deployment

- Free tier: Basic compatibility overview, daily cosmic weather, natal chart viewer
- Premium subscription: $9.99/month — full reports, AI chat, daily digest
- Annual plan: $79.99/year — same features, 33% savings
- Single report: $4.99 one-time — for users who want one deep-dive without subscribing
- Promo codes supported for growth campaigns

Show HN: ChartChemistry — AI astrology compatibility using Swiss Ephemeris + Claude

Hey HN,

I built ChartChemistry (https://chartchemistry.com), a web app that calculates real astrological compatibility between two people using their birth data.

What it does:
- Takes birth date, time, and location for two people
- Calculates precise planetary positions using Swiss Ephemeris (pyswisseph) via a Python FastAPI microservice
- Computes synastry aspects, house overlays, and composite charts
- Claude AI interprets the chart data into a readable compatibility report

The technical stack:
- Next.js 16 with App Router and React 19 for the frontend
- Python FastAPI microservice wrapping pyswisseph for astronomical calculations
- Claude Sonnet for report generation, GPT-4.1 Nano for the chat interface
- PostgreSQL (Supabase) with Prisma ORM
- Stripe for payments, Resend for transactional email

Why I built it: Most astrology apps use templated text based on sun signs. I wanted to see what happens when you combine real astronomical data with modern AI interpretation. The Swiss Ephemeris calculations are the same ones professional astrologers use — it's the interpretation layer where AI adds value.

The free tier gives you a real compatibility overview (not a teaser). Happy to answer questions about the architecture or the astrology domain modeling.

I built a free tool that calculates zodiac compatibility beyond just sun signs

I've been into astrology for years and always felt frustrated that most compatibility tools only look at sun signs. So I built a web app that actually calculates synastry from full birth chart data.

You enter birth date, time, and location for two people, and it computes all the planetary positions using Swiss Ephemeris (the same engine used by professional astrology software). Then it analyzes the aspects between the two charts — not just sun-to-sun, but Moon, Venus, Mars, Mercury, and the outer planets too.

The free version gives you a real compatibility overview with scores across different dimensions (emotional, intellectual, physical, spiritual). It's not a paywall teaser — you get actual analysis.

I'd genuinely love feedback from this community since you all know way more about astrology than I do. What aspects or house overlays do you think matter most for compatibility?

Link: https://chartchemistry.com

I built an AI-powered astrology compatibility app

Just shipped ChartChemistry (https://chartchemistry.com) — an AI-powered astrology compatibility tool.

The idea: most astrology apps match people by sun sign. I wanted to build something that uses real astronomical calculations (Swiss Ephemeris) and AI (Claude) to generate actual compatibility reports from full birth chart data.

Tech stack:
- Next.js 16 + TypeScript frontend
- Python FastAPI microservice for Swiss Ephemeris calculations
- Claude AI for report writing, GPT-4.1 Nano for chat
- PostgreSQL (Supabase), Stripe, Vercel

What I learned:
- Astrology domain modeling is surprisingly complex (12 houses, 10+ celestial bodies, 5 major aspect types, orb calculations)
- Swiss Ephemeris is incredibly precise but has a steep learning curve
- AI interpretation of chart data works better than I expected when you give it structured input
- The compatibility niche has high organic search potential (people Google "[sign] + [sign] compatibility" constantly)

Revenue model: Free tier with basic analysis, $9.99/mo premium, $4.99 single reports.

Happy to answer questions about the build!

Built a Next.js app using Swiss Ephemeris + Claude AI for astrology compatibility

Sharing a project I recently shipped: ChartChemistry (https://chartchemistry.com), an astrology compatibility app.

Interesting technical challenges:

1. **Swiss Ephemeris integration**: Runs as a Python FastAPI microservice using pyswisseph. Calculates planetary positions to arc-second precision for any date/time/location. Had to implement a circuit breaker pattern for reliability.

2. **AI pipeline**: Claude Sonnet generates compatibility reports from structured chart data. GPT-4.1 Nano handles the chat interface and daily horoscopes. Both use lazy-initialized singletons with 30s timeouts and bidirectional failover.

3. **Animated natal chart**: SVG-based chart wheel with ring draw-in animations (2.5s), staggered planet placement, aspect line drawing, and hover highlights. Built with Framer Motion.

4. **Programmatic SEO**: 78 zodiac pair pages (/compatibility/aries-taurus, etc.) using ISR with 24h revalidation. Each has 600+ words of unique content.

5. **Auth + payments**: NextAuth v4 with JWT strategy (Google OAuth + credentials), Stripe for subscriptions ($9.99/mo, $79.99/yr) and single-report purchases ($4.99).

Stack: Next.js 16, React 19, TypeScript, Tailwind v4, Prisma 7, PostgreSQL (Supabase), Vercel.

Would love feedback on the architecture — especially the microservice pattern for the ephemeris calculations.

Co-Star, The Pattern, Sanctuary Astrology

ChartChemistry is an AI-powered astrology compatibility platform. It uses Swiss Ephemeris for precise astronomical calculations and Claude AI for personalized report generation. Enter birth details for two people and get a detailed synastry report covering emotional, intellectual, physical, and spiritual compatibility. Features include animated natal chart viewer, personal AI astrologer chat, daily cosmic weather, shareable social cards, and a monthly cosmic events calendar. Free tier available with premium deep-dive reports.

Astrology, Compatibility, AI, Birth Chart, Natal Chart, Synastry, Horoscope, Zodiac, Relationships

ChartChemistry

AI-powered astrology compatibility reports from real birth chart data

ChartChemistry uses Swiss Ephemeris astronomical calculations and Claude AI to generate real astrology compatibility reports. Unlike sun-sign-only apps, it analyzes the full synastry between two natal charts.

What you get with a lifetime deal:
- Unlimited compatibility reports (full premium deep-dive)
- Personal AI astrologer chat (Marie)
- Daily personalized cosmic weather and horoscopes
- Animated natal chart viewer with interactive SVG wheel
- Shareable cosmic identity cards and Instagram/TikTok story cards
- Monthly cosmic events calendar
- Priority access to new features

How it works:
1. Enter birth details (date, time, location) for two people
2. Swiss Ephemeris calculates precise planetary positions
3. AI analyzes synastry aspects, house overlays, and composite patterns
4. Get a personalized compatibility report in natural language

Tier 1 ($29): Lifetime premium access, 1 user
Tier 2 ($59): Lifetime premium access, 3 users
Tier 3 ($99): Lifetime premium access, unlimited users + early feature access

I just launched ChartChemistry — an AI-powered astrology compatibility app that uses real astronomical calculations, not just sun sign matching.

Here's what makes it different (thread):

Most astrology apps match you by sun sign alone. That's like judging a book by one page.

Your full birth chart has 10+ celestial bodies, 12 houses, and dozens of aspects. That's where real compatibility lives.

ChartChemistry uses Swiss Ephemeris (the same engine professional astrologers use) to calculate exact planetary positions from your birth time and location.

Then Claude AI interprets the synastry between two charts into a personalized report.

What you get:

• Real synastry analysis (not templates)
• Emotional, intellectual, physical & spiritual scores
• Animated natal chart viewer
• AI astrologer chat (Marie)
• Daily cosmic weather
• Shareable story cards for IG/TikTok

Built with:

• Next.js 16 + React 19
• Python FastAPI + Swiss Ephemeris
• Claude AI (reports) + GPT-4.1 Nano (chat)
• PostgreSQL + Prisma
• Stripe payments

The astronomical calculations are real. The AI just makes them readable.

The free tier gives you a real compatibility overview — not a paywall teaser.

Premium ($9.99/mo) unlocks full deep-dive reports, Marie chat, and daily digest emails.

Or grab a single report for $4.99.

Try it free: https://chartchemistry.com

I'd love to hear what you think. Drop your and your partner's signs below and I'll tell you what to expect from the full report.

Launching on Product Hunt soon — follow along!

I just launched something a little different.

ChartChemistry is an AI-powered astrology compatibility app that uses real astronomical calculations to analyze relationship chemistry.

Here's why I built it:

Most astrology apps match people by sun sign alone. But your full birth chart contains 10+ celestial bodies across 12 houses with dozens of interplanetary aspects.

I wanted to see what happens when you combine:
• Swiss Ephemeris (the gold standard for astronomical calculations)
• Claude AI (for natural language interpretation)
• Real synastry analysis (how two charts interact)

The result is a compatibility report that covers emotional connection, intellectual chemistry, physical attraction, and long-term potential — all calculated from precise planetary positions.

The technical build was fascinating:
• Python microservice wrapping Swiss Ephemeris for astronomical math
• Next.js 16 frontend with animated SVG chart wheels
• AI pipeline using Claude for reports and GPT-4.1 for chat
• 78 programmatic SEO pages for zodiac pair combinations

Whether you're into astrology or just curious about the AI + domain-specific-data pattern, I'd love your thoughts.

Try it free: https://chartchemistry.com

#astrology #ai #sideproject #buildinpublic #nextjs

[HOOK - 0-3 seconds]
(Text overlay: "POV: You find out your REAL zodiac compatibility score")
(Show phone with ChartChemistry open)

[SETUP - 3-10 seconds]
"So you know how every astrology app just matches your sun signs? Like 'oh you're a Scorpio and they're a Taurus, good luck'?"

[TENSION - 10-20 seconds]
"I found this app called ChartChemistry that uses your FULL birth chart. Like, the exact position of every planet when you were born."

(Show entering birth details for two people)

"It calculates the actual astronomical positions using the same engine professional astrologers use."

[REVEAL - 20-40 seconds]
"And then AI writes you a real compatibility report."

(Show the report loading / results appearing)

"Look at this — it breaks down emotional connection, intellectual chemistry, physical attraction, and long-term potential separately."

(Scroll through report sections)

[CTA - 40-50 seconds]
"The free version actually gives you real results, not just a teaser."

(Text overlay: "chartchemistry.com" + "Link in bio")

"Go try it with your person and tell me your score."

[END]
(Text overlay: "What did you get? Comment below")

Your sun sign is just the beginning.

We just launched ChartChemistry — a compatibility tool that actually calculates your full birth chart and tells you how your planets interact with theirs.

Not templates. Not generic horoscope matching. Real astronomical calculations + AI interpretation.

What you get:
✨ Full synastry report (emotional, intellectual, physical, spiritual)
🌙 Animated natal chart viewer
💬 Personal AI astrologer (Marie)
☀️ Daily cosmic weather

Free to try. Link in bio.

Tag someone you want to check your compatibility with 👇

#astrology #zodiac #compatibility #birthchart #synastry #natalchart #zodiacsigns #astrologytiktok #relationships #aistrology

Be honest: have you ever looked up your compatibility with someone based on JUST sun signs?

Here's the thing — your sun sign is maybe 10% of the picture.

Your Moon sign shows emotional compatibility.
Your Venus sign shows love language.
Your Mars sign shows physical chemistry.
Your Mercury sign shows communication style.

ChartChemistry analyzes ALL of them between two people.

What's your big 3? Drop it below and we'll tell you what to look for in a partner 👇

#astrology #sunsign #moonsign #venussign #bigtree #zodiac #compatibility #birthchart #astrologymemes

"I never believed in astrology until I saw our actual chart compatibility broken down planet by planet."

ChartChemistry doesn't guess. It calculates.

Using Swiss Ephemeris (the same engine professional astrologers use), it maps the exact position of every planet at your birth, then analyzes how your chart interacts with theirs.

The result? A compatibility report that actually explains WHY you click with some people and clash with others.

Try it free — link in bio.

Save this for when you start talking to someone new 😏

#astrology #compatibility #synastry #relationships #zodiac #birthchart #natalchart #astrologersofinstagram