# Celestio

> Celestio calculates precise birth charts for any person, any place worldwide and any date from 1900 to 2100 (birth time optional) and writes a personal reading of each chart, free. It also sells two-person compatibility reports (one payment, base price US$14.99; regional prices may be lower) and personal 30-day Transit reports with a free calculated preview and one payment for the full report. The homepage, Compatibility page and checkout show the same price for the visitor. Tagline: "Written in the stars. Read for you."

Readings are written by an AI model from the calculated chart; members keep them in their library and can share them. Anyone can enter anyone's birth details.

## For people

- [Free birth chart reading](https://celestio.ai/birth-chart): name, birth date, place and optional time; the chart is drawn at once and the reading is written as you watch. Works without an account; creating one keeps the readings.
- [Compatibility](https://celestio.ai/compatibility): two people and how they relate (partner, crush, friend, family); free preview of the strongest connections, then the full written report.
- [Transits](https://celestio.ai/transits): one person and an editable 30-day period; free calculated preview, then one payment for the full personal Transit report, saved in My readings. The visitor's offer shows the price before payment.
- [Your readings](https://celestio.ai/readings): the library of a signed-in member.
- [Membership](https://celestio.ai/membership): daily readings for one frozen chart and home timezone, one exact paid-period overview and two Compatibility reports per paid period, no rollover. New billing stays on the authenticated website; saved reports remain after cancellation.
- [Career](https://celestio.ai/career) and [Self-understanding](https://celestio.ai/self-understanding): separate one-time reports with calculated free previews. Personal reports are separate from membership.

## For assistants and agents

- [Use Celestio in your AI](https://celestio.ai/ai): setup for ChatGPT, Claude, Grok, Gemini, Perplexity and coding agents.
- MCP server (Streamable HTTP, OAuth 2.1): https://celestio.ai/mcp. Without an account: compute_birth_chart (a chart and a link to its free reading) and compare_birth_charts (two people's strongest connections and a link to the free compatibility preview). With the person's Celestio account: get_birth_reading, list_my_readings, get_reading, preview_compatibility, preview_transits, and, when the person allows it, start_compatibility_purchase and get_purchase_status.
- [OpenAPI](https://celestio.ai/api/v1/openapi.json): POST /api/v1/charts computes a chart without an account.
- Browsing assistants can use the website directly: the birth form has labelled fields and a place picker.
- preview_transits requires create permission and takes exactly one owned chartId or person, plus optional start (YYYY-MM-DD). It calculates the existing 30-day preview, defaulting to today in the birthplace timezone, with literal dates and supported contacts. With read permission it returns owned frozen purchase state and saved reading handles; list_my_readings and get_reading include the stored Transit period and presentation.
- Unrestricted clients may return an account-authenticated Transit website continuation for that exact chart and period: the owner signs in to the same account, sees the browser's actual price and completes payment. Directory clients receive no purchase continuation or price. No Transit payment tool exists; purchases permission remains Compatibility-only. Browsing assistants can use the [Transits website flow](https://celestio.ai/transits).
- Permitted non-directory clients also have get_membership_status, get_membership_report (due entitled daily/period work), preview_personal_report, get_personal_report (already-settled Career/Self-understanding only), and redeem_compatibility_credit with its separate default-off grant. The purchases permission remains Compatibility-only. Existing list_my_readings/get_reading retrieve all saved kinds with frozen report metadata. Restricted ChatGPT/Claude directory mode has none of these new tools, redemption or transactional continuations; hidden direct calls are refused. Muse/Grok interoperability for these journeys remains unverified.

## Company

- celestio.ai. Contact: support@celestio.ai
- [Terms](https://celestio.ai/terms), [Privacy](https://celestio.ai/privacy)

## Learn astrology

- [Learn](https://celestio.ai/learn): guides to signs, planets, houses and aspects
- [Astrology Glossary: Birth Chart Terms, Clearly Explained](https://celestio.ai/learn/astrology-glossary-decode-your-chart): Plain, accurate definitions of the words on your birth chart, from Ascendant and Midheaven to orbs, sect, the lunar nodes and the different Liliths.
- [Sample Birth Chart Reading: Maya, Sun in Taurus with Taurus Rising](https://celestio.ai/learn/sample-birth-chart-report): A complete sample birth chart reading for Maya, a fictional person born in Lisbon: the chart at a glance and seven sections written for those exact placements.
- [Sample Compatibility Report: Maya and Leo](https://celestio.ai/learn/sample-compatibility-report): A full sample compatibility report for Maya and Leo, a fictional couple: their two birth charts read together, contact by contact, in seven sections.
- [Celestio FAQ](https://celestio.ai/learn/resources): Answers to common questions about Celestio: the free birth chart reading, compatibility reports, birth times, house systems and sharing.

## Blog

- [Zodiac Signs vs Constellations: What Your Chart Measures](https://celestio.ai/blog/zodiac-signs-vs-constellations): Your tropical zodiac sign comes from a measured position on a twelve-part circle. Constellations map the background sky. Here is how to tell the two apart.
- [Birth Chart Without a Birth Time: What You Can Still Read](https://celestio.ai/blog/birth-chart-without-birth-time): Without a birth time you can still read your Sun, the signs of Mercury through Pluto and most aspects. The rising sign, houses, angles and the Moon's exact degree need the time.
- [Composite Chart vs Synastry: What's the Difference?](https://celestio.ai/blog/composite-chart-vs-synastry): Synastry overlays two birth charts to show how each person experiences the other. A composite chart blends them into one chart that describes the relationship itself.
- [Empty Houses in Astrology: What an Empty House Means in Your Chart](https://celestio.ai/blog/empty-houses-birth-chart): Every chart has empty houses, because ten planets cannot fill twelve houses. An empty house is still active: read it through the sign on its cusp and that sign's ruling planet.
- [Midheaven (MC) Meaning: Your Public Direction in the Birth Chart](https://celestio.ai/blog/midheaven-mc-meaning): The Midheaven (MC) is the zodiac degree culminating on your local meridian at birth. It describes your public direction, your reputation and the work you want to be known for.
- [Placidus and Orb 0 on a Birth Chart: What the Settings Mean](https://celestio.ai/blog/placidus-orb-birth-chart-settings): Placidus and Orb 0 are separate chart settings. Placidus is how the houses are drawn; Orb 0 in the header most likely means no planet moves into a house before its cusp.
- [Saturn Return: What It Is, When It Happens and How It Feels](https://celestio.ai/blog/saturn-return): A Saturn return is when Saturn comes back to where it was when you were born, about every 29.5 years. The first exact return falls between about 28 and 30.
- [The 7th House in Astrology: Partnership, Marriage and the Descendant](https://celestio.ai/blog/seventh-house-astrology): The 7th house rules partnership, marriage and every close one-to-one bond. Its sign, the Descendant, describes the qualities you look for in others and meet through them.
- [Stellium Meaning: What Three or More Planets Together Mean](https://celestio.ai/blog/stellium-meaning): A stellium is three or more planets gathered in one sign or one house. It turns that sign or area of life into a defining theme of your chart.
- [Synastry House Overlays: When Their Planets Fall in Your Houses](https://celestio.ai/blog/synastry-house-overlays): A house overlay is where one person's planets land in the other's houses. It shows which part of your life someone lights up, and you read it in both directions.
- [Whole Sign vs Placidus Houses: Which House System Should You Use?](https://celestio.ai/blog/whole-sign-vs-placidus-houses): Whole Sign makes each house one whole sign starting with your rising sign; Placidus divides the sky by time. Your signs and rising never change, only some house placements.
- [The Best Synastry Aspects for Long-Term Compatibility, Not Just Chemistry](https://celestio.ai/blog/best-synastry-aspects-long-term-compatibility): Chemistry brings two people together; other contacts keep them there. The synastry aspects astrologers link with lasting bonds: the Sun and Moon, Moon and Venus, Saturn and Jupiter.
- [Mercury in Synastry: How You and Your Partner Actually Communicate](https://celestio.ai/blog/mercury-synastry-communication-compatibility): Mercury in synastry shows how two people think and talk together: the pace, the humour, the arguments and the repairs. Here is how to read each Mercury contact.
- [Moon Compatibility in Synastry: Why Emotional Fit Outlasts Sun Signs](https://celestio.ai/blog/moon-compatibility-emotional-fit-sun-signs): Moon compatibility shows whether two people can feel safe, comforted and at home with each other. Here is how astrologers read every Moon contact between two charts.
- [Venus–Mars Synastry: Attraction, Chemistry and How It Plays Out](https://celestio.ai/blog/venus-mars-synastry-chemistry-attraction-tension): Venus–Mars synastry is astrology's classic signature of attraction. Here is how each aspect feels, why direction matters, and what chemistry needs in order to last.
- [The 5 Synastry Aspects That Feel Fated, and What They Really Mean](https://celestio.ai/blog/5-most-important-synastry-aspects): Five synastry contacts produce that sense of recognition at first meeting: Sun–Moon, the Ascendant, the nodes, Saturn and Pluto. What each means, and how to tell a rare contact from a common one.
- [What Is Synastry? How Two Birth Charts Explain a Relationship](https://celestio.ai/blog/what-is-synastry-birth-chart-relationship-dynamics): Synastry compares two whole birth charts to show how two people meet: the aspects between their planets, whose planet touches whose, and where each lands in the other's life.
- [Birth Chart Compatibility vs Zodiac Signs: Why Sun Signs Aren't Enough](https://celestio.ai/blog/birth-chart-compatibility-vs-zodiac-sun-signs): Sun-sign compatibility compares one placement each. Birth chart compatibility reads both whole charts. How the two differ, and how to move from your Sun pair to your Moon and Venus pairs.
- [How to Read Your Birth Chart: A Step-by-Step Method](https://celestio.ai/blog/how-to-read-your-birth-chart-step-by-step): Read your birth chart in the order experienced astrologers use: the Ascendant and its ruler first, then day or night, the Sun and Moon, the key planets and the aspects.
- [What's My Mars Sign? How You Fight, Desire and Set Boundaries](https://celestio.ai/blog/whats-my-mars-sign-fight-desire-boundaries): Your Mars sign shows how you act, want, argue and defend your boundaries. How to find it, what retrograde Mars and day or night births change, and all twelve signs.
- [What's My Venus Sign? Love Style, Values and What You're Drawn To](https://celestio.ai/blog/whats-my-venus-sign-love-style-attraction): Your Venus sign shows how you give and receive love, what you find beautiful and what you value. How to find it, what retrograde Venus means, and all twelve signs.
- [What's My Rising Sign? Your Ascendant and Why It Shapes Your Chart](https://celestio.ai/blog/whats-my-rising-sign-ascendant-birth-chart): Your rising sign, or Ascendant, is the sign rising on the eastern horizon at your birth. How to find it, why minutes matter, and what each one means.
- [How to Find Your Moon Sign and What It Says About Your Emotional Needs](https://celestio.ai/blog/find-your-moon-sign-emotional-needs): Your Moon sign shows what you need to feel safe and how you react before you think. How to find it, what to do if the Moon changed sign that day, and what each one means.
- [Chart Ruler in Astrology: How to Find the Planet That Rules Your Chart](https://celestio.ai/blog/chart-ruler-explained-planet-running-your-birth-chart): Your chart ruler is the planet that rules your rising sign. Its sign, house and aspects show where your life's attention goes. How to find yours and read it, with a worked example.
- [North Node and South Node: The Lunar Nodes Explained](https://celestio.ai/blog/lunar-nodes-north-node-south-node-explained): The lunar nodes are the two points where the Moon's path crosses the Sun's. What the North and South Node mean in your chart, true vs mean node, and the 18.6-year nodal cycle.
- [Astrological Transits: What They Are and How to Read Them](https://celestio.ai/blog/understanding-astrological-transits-guide): A transit is a planet in today's sky meeting a point in your birth chart. How long each planet's transits last, why some hit three times, and a simple way to read them.
- [Planet, Sign, House: The Astrology Formula for Reading Any Placement](https://celestio.ai/blog/astrology-formula-planet-sign-house): Read any placement as one sentence: the planet is what acts, the sign is how it acts and the house is where it shows up. Worked examples, and the layers that come next.
- [Astrological Aspects: How the Planets in Your Birth Chart Talk](https://celestio.ai/blog/cosmic-conversation-astrological-aspects-birth-chart): Aspects are the angles between the planets in your birth chart. What each major aspect means, how orbs work, and how to read applying, out-of-sign and hard aspects.
- [The Planets in Astrology: What Each One Means in Your Birth Chart](https://celestio.ai/blog/meet-the-planets-key-players-birth-chart): Each planet in your birth chart is a different part of you: the Sun your identity, the Moon your needs, Mercury your mind, Venus your love, Mars your drive, and so on outward.
- [The 12 Zodiac Signs: Elements, Modalities and Meaning in Your Chart](https://celestio.ai/blog/12-zodiac-signs-archetypes-birth-chart): The 12 zodiac signs are twelve styles of being, from Aries' first spark to Pisces' open heart. Each sign's element, modality and ruler, and how signs color every planet in your chart.
- [The 12 Houses of Astrology: What Each House Means in Your Chart](https://celestio.ai/blog/12-houses-of-astrology): The 12 houses divide your birth chart into areas of life: self, money, home, love, work, partners, career and more. What each one means, in modern and traditional astrology.
- [Your Astrology Big 3: Sun, Moon and Rising Signs Explained](https://celestio.ai/blog/astrology-big-3-sun-moon-rising): Your Big 3 are your Sun, Moon and rising signs. What each one means, why the rising sign needs a birth time, and how to read the three together.
- [What Is the Placidus House System? Placidus vs Other House Systems](https://celestio.ai/blog/placidus-vs-other-house-systems): The Placidus house system divides each quarter of the chart into three by time, so houses come out unequal. How it works, why it became the default, and how it compares.