Wrote to a dog, got a reply 23 hours later: how a small Korean team made "free fortune-telling" truly free and still made money

Korea has more fortune-telling apps than you can count. Sulsul Saju does one thing: you write your worries as a letter to a cartoon dog, "Sulsul-i," and it reads your birth chart and replies in about 23 hours. The full reply is free. If you don't want to wait, you can pay two or three thousand won to read it immediately, and that's how it makes money. It's not a new app: it's been around for two years, isn't huge, and ranks around #50 on Korea's Lifestyle top-grossing chart. What's worth watching is its monetization model, and that it has just started selling "Korean fortune-telling" in Taiwan.

A review from Sep 27

In 2026 Sep 27, a Korean user gave Sulsul a 5-star rating on the App Store and wrote a long review:

"Other Instagram-linked love-Saju apps say it's free in the ads, then you get in and it wants money, so annoying. Sulsul-i isn't like that. You do have to wait a day, but it's free, and if you check in you can sometimes read it right away... the dog is so cute, it's healing, it feels less like fortune-telling and more like counseling."

That review pretty much explains the business: users come in from Instagram ads that say "free," and it really is free, just with a wait. The standard Korean fortune-app playbook is "read a bit free, unlock the details for money," and users have been burned by it many times, so an app that keeps its word stands out. Another App Store review (11-02) was more blunt: "I only tried it because the Instagram ad said free, and it really is free?! You wait about 23 hours."

What it is

• Developer: Aves LLC., a small company in Seocho-gu, Seoul, which also has a werewolf-style party game, a group-expense tracking app, and a supplement brand.
• Launch date: iOS version released in Sep 2024 6 (per iTunes release date). The Google Play store page now shows 2026-09-08, which is the date after the info reset, not the original launch. Before the app, it first ran as a web version at sulsulsaju.com, whose landing page read: "Write down any worry and get a reading of 1000+ characters. It's not like a chatbot."
• Core mechanic: pick a topic (love, getting back together, compatibility, career, wealth, starting a business, or "how well do I match my bias"), write down your worry, enter your birth date and time, and Sulsul-i replies with a long letter. There are also daily fortunes, home- and lock-screen widgets, and streak check-ins. The October 26 update added "2027 Year of the Fire Goat New Year fortune" and put it in the title.
• Pricing: no ads, in-app purchases from $0.69 to $74.99. It uses two in-app currencies, bones and bone fragments. Reading a reply right away costs 3 bones; check-ins give fragments, and 10 fragments convert to 1 bones.

Why this one: turning "unlock content" into "buy time"

Korean fortune apps usually charge for content, so without paying you only see the opening. Sulsul gives the whole reading for free and charges for waiting. That does three things:

1. The ads hold up. Instagram ads can safely say "free," and users don't feel tricked when they arrive, so ratings stay steady: 1,396 iOS ratings in Korea averaging 4.68; 4.7 on Google Play from 643 reviews (11-06).
2. The people willing to pay are the most impatient. Most people who come for a Saju reading ask about love or getting back together, and these are the users who most want to know right now. A user wrote in a Sep 28 review: "Sulsul-i's words are so warm, thank you... but 24 hours is really long~~~" People who find the wait too long are exactly the ones who will pay.
3. Waiting for the reply is itself engaging, and it saves money. Waiting for a letter builds anticipation, and reviews keep using words like "cute" and "healing" and "like counseling," with few people saying it feels AI-written. Since it doesn't need real-time replies, generation can be batched and scheduled for off-peak hours, which lowers inference costs (inferred).

Then there's the Samoyed. The mascot is based on Korea's native breed, the Sapsaree, and the developer replied to reviews in the dog's voice, ending sentences with "~meong" (woof). There's also a small "burn away bad luck" interaction, and a July review praised it as a "genius feature." At its core it sells emotional comfort more than fortune-telling. The main users are likely women in their twenties and thirties (inferred: iOS rating count is more than double the Play review count, which matches the typical profile of Korean fortune-app users).

Some users push back on the pricing too. One review from Oct 20, 1 stars: "Watching an ad costs 2,000–3,000 won, which is pricier than most utility apps. I check in every day to collect bones, and then find out the reward is fragments. It takes 10 fragments to get 1 bone, and watching an ad needs 3 bones. So I'd have to check in for 30 days to skip once for free." Another Oct 19 review says they had enough bones, yet a single tap on "use" still jumped to the payment page. These complaints actually show the paywall is pushing people to pay.

Where users come from

Searching "술술사주" on TikTok turns up nothing relevant, and no media outlet has covered it.

How big is it?

Not big. Google Play cumulative installs worldwide are 24,873, up 7 in the last 617 days, roughly ninety a day. iOS is the main channel, with more than twice as many Korean-store ratings as Play reviews. On charts, Play's Korea Lifestyle Top Grossing has sat at #49 to #54 (10-29 to 11-06), and its best iOS Korea Lifestyle Top Grossing rank is #61. In Korea, #50 to #60 in Lifestyle Top Grossing is not high. Monthly revenue is likely tens of millions of won (estimate, unverified, roughly $20K to $50K).

November It launched a Traditional Chinese version, "順順八字－韓國算命・煩惱諮詢・暖心回信". Starting 11-05, it entered the Taiwan Play Lifestyle Top Free chart at #143 to #148. On the iOS Taiwan store it has only 5 ratings, so it is still getting started.

Who it's competing with

The Korean category is very crowded. "AI fortune-telling + cartoon characters" has been an established niche for 2026 years, and 술술 sits mid-pack:

The two biggest ways 술술 differs from them: first, it's letter-writing where you wait for a reply, not instant chat; second, it's free but you wait, unlike others that give you a taste before charging. Both are easy to copy, and there are already similar products that launched more than a year after it and have passed it in ranking and revenue.

If it were you

In one line: Don't fight it in Korea. The "write a letter, wait for a reply, pay to skip the wait" model can be moved to other markets, and its move into Taiwan suggests it's thinking the same way.

Who it suits: small teams who understand a market's fortune-telling culture (Bazi, Zi Wei, tarot, astrology, Japanese divination), can run Meta ads, and can polish characters and copy. The technical bar is low: one LLM plus a Bazi chart-calculation library is enough.

Who it doesn't suit: people who don't want to run ads and are counting on organic traffic alone. 술술's users almost all come from ads. It has no well-established character persona and no "free" experience that actually delivers, so ad spend is wasted. It also doesn't suit anyone wanting to build in Korea, where the top spots are held by big platforms and funded character products.

How to build it: Replies must be long, complete, and free, so the first letter makes people feel "they really didn't scam me." Charge only for "read it now," priced under the cost of a coffee. Check-ins and home-screen widgets bring people back daily. The character needs its own voice, and replies to comments should also use the character's tone. Markets to consider: Taiwan, Hong Kong/Macau, and Southeast Asian Chinese communities for Bazi and Zi Wei; Japan for divination; English-speaking markets for tarot and astrology. Pick a category in your target market that still relies on "give a little, then pay to unlock".

How to acquire users: Instagram / Meta ads pitched as "truly free, you just have to wait," with creatives built from character and reply screenshots. Store titles and keywords should target what's timely this season: New Year fortune, Valentine's compatibility, exam luck. In Taiwan, you could add earned exposure on Threads and Dcard (suggestion, unverified).

When to launch: The biggest Chinese-market peak is before Lunar New Year in 2027 (Lunar New Year falls on Feb 6). Aim to launch before mid-January to catch the New Year fortune search peak. If you miss it, target the next peak and watch how far 順順八字 grows in Taiwan.

Where the read could be wrong: ① After the Korean New Year peak (after February 2027), 술술 dropped out of the top 100 Korea Lifestyle Top Grossing, suggesting it mostly rides seasonality and the payment model alone can't hold it up. ② By March 2027, 順順八字 in Taiwan still had only a few dozen ratings and had fallen off the Free chart, suggesting "Korean fortune-telling" and this payment model may not work in other markets. ③ Korea's top players (Hellobot, 점신) have also adopted the "free wait" model without any visible growth, suggesting ads, not the payment model, are what's actually driving results.

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Data and sources: Google Play store pages, install counts and charts (2026-10-29 to 11-06); App Store Korea storefront pages, ratings and reviews (as of 11-06); iTunes release-date lookup; sulsulsaju.com; aves.llc; Instagram @sulsulsaju; Kakao channel "술술"; 사주랭크; tistory blog "2026 사주/운세 앱 BEST 5" (2025-10). Revenue figures are estimates, unverified.