Comparison
Which astrology app is best for compatibility?
It depends on the question. For a fixed compatibility reading between two charts, Co-Star (free) and Astro-Seek (free, no account) do the job; for day-by-day dates over the pair's next 90 days, only Cosmea does that, and The Pattern comes closest with "Romantic Timing" cycles for subscribers.
Of the seven tools checked on September 22, 2026, one gives a day-by-day calendar for the pair and a second offers timing cycles; the other five deliver a fixed reading. Venus is retrograde for 42 days in 2026, and no fixed synastry reading changes during them.
| Tool | Compares two charts | Other person's birth time | Dates for the pair | Listed price | Where |
|---|---|---|---|---|---|
| Cosmea | Yes: the points where the two charts touch, the relationship chart (composite) and the moving planets over both charts | Optional; without it the Moon enters with declared uncertainty and half weight | Yes: 90 days, one by one, as a flowing, ordinary or tense day (green, yellow and red), with the reason for each day | 7 days free; R$ 24.90 once, no subscription | Browser (phone or desktop); no birth data leaves the device |
| Co-Star | Yes: add friends and compare natal charts | Asks date, time and place at signup; people without the app are added via "Add Manually" ($2.99) | Not listed; the compatibility reading is fixed | Free; a la carte purchases (relationship chart $8.99, Pro-Star $8.99/month) | iOS and Android app |
| The Pattern | Yes: "Bonds" between you and anyone you add | Asks for the other person's birth data ("Custom Friend") | Partial: "Romantic Timing cycles" in Bond Transits, subscribers only | Free with limits; Go Deeper+ $14.99/month, $29.99/quarter or $83.99/year | iOS and Android app |
| CHANI | Not listed: the official free and premium feature list has no synastry | Not applicable | No: weekly horoscopes and a reading of your own chart | Subscription $11.99/month or $107.99/year, with a free trial | iOS and Android app |
| Astro-Seek | Yes: synastry chart with aspects and interpretations | Asks both times; planet-to-planet aspects work without it | No: the chart is fixed; general transit calendars exist, not the pair's | Free, no account | Website |
| Personare | Yes: Sinastria Amorosa compares both charts | "With birth times recorded this analysis becomes even more complete" | No: "the synastry between two people does not change with time" | Free sample (the Venus chapter); full version paid, price shown in your account | Website in Portuguese, login required |
| Astrolink | Yes, Premium only: between your main chart and one saved extra chart | Time "increases precision, but you can create a chart without it" | Not listed for the pair; the Lunar Cycle (premium) suggests days for you | Free chart; synastry only on the monthly Premium subscription, auto-renewing | Website and Android app, in Portuguese |
How we compared
Four questions, answered by what each product's official page, store listing or help centre said on September 22, 2026: does the tool compare two birth charts? What happens when you do not know the other person's birth time? Does it give dates for the pair, or a fixed reading? What does it cost, and is it a subscription?
We did not test the quality of each app's interpretation and we do not score. "Not listed" means the source does not mention the feature, not that the product lacks it. Prices are the US App Store or the Brazilian site on that date and may change.
Cosmea is in the table because this is Cosmea's site. The criteria are the ones that matter to someone who wants to know when to talk, not only whether you match.
What each one does well
Co-Star
The strength is the social layer: you add friends and compare charts inside the app, on the free tier; what you pay for are one-off reports and Pro-Star. If the person does not have the app, you add them for $2.99.
What is missing for our question: the two-chart reading never turns into dates. You learn how you get along, not when.
The Pattern
The only app on the list, besides Cosmea, that talks about timing for the pair: "Romantic Timing cycles" sit inside Bond Transits for Go Deeper+ subscribers, and "Time Travel" shows any cycle on a chosen day.
It is the most expensive option in the table, on subscription, and what it delivers are cycles, not a 90-day calendar with one colour per day.
CHANI
Weekly horoscopes by rising sign, a human-written chart reading, meditations. It is not a couples app: the official feature list has no synastry, and the annual subscription is $107.99.
Astro-Seek
A complete synastry chart, free and without an account, with the aspect table and interpretations. If you want the glyphs and the degrees, this is the place. Without the other person's time, planet-to-planet aspects still hold; the houses do not.
Everything is fixed: there are no dates for the pair.
Personare
The Brazilian option for a long written reading: Sinastria Amorosa has a free sample (both wheels and the Venus chapter) and a paid full version delivered by email to read on the site. Personare itself says the synastry "does not change with time", which is true and is exactly what it does not answer: when.
Astrolink
A free birth chart in plain Portuguese, with up to two extra charts on the free plan. Synastry lives in Premium, only between your main chart and one saved chart. The Lunar Cycle suggests days, but for you, not for the pair.
Cosmea
You enter both births and get 90 days, one by one, in green, yellow and red, each with its reason in plain words ("Venus in harmony with your Moon"). The other person's birth time is optional: without it the Moon enters with declared uncertainty and counts half. The calculation runs in the browser; the server receives only the colours and the reasons.
The first 7 days open without an account or payment. Then R$ 24.90 once, via Pix, and the calendar is yours. It is astrological interpretation, not prediction: green means tradition favours getting closer that day; red, that it asks for patience.
When Cosmea is not the right pick
- You want a daily horoscope about you, not about the two of you: Co-Star or CHANI.
- You want the full synastry chart, every aspect and the houses, for free: Astro-Seek.
- You want a long written psychological profile of the pair to read slowly: The Pattern or Personare's Sinastria Amorosa.
- You want a native app with push notifications and a friends network: Co-Star or The Pattern. Cosmea runs in the browser and writes by email.