"Low wages, so you have to keep track": a Vietnamese programmer turned a budgeting app into a monthly calendar that changes colour, and filmed the videos himself to push it onto the bestseller chart
What it is A budgeting app that opens to a monthly calendar. Each day is shaded in a different intensity according to how much you spent, and it tells you how much you can still safely spend today. Free, with a Pro subscription.
Why it took off The developer filmed short skits on TikTok about "low pay so I have to track spending" and "asking my husband for money," which Vietnamese viewers identify with. One video with 157k views brought in a wave of downloads, and the Vietnamese finance bestseller chart has a very low bar, so a few subscriptions were enough to reach the top 20.
BHow you could follow it Don't copy it in Vietnam. Take the "colour-coded monthly calendar + local pricing + founder filming his own life skits" package to markets like Indonesia, Thailand or Latin America, where nobody has done this yet, and fill in what it lacks: an Android version and shared household ledgers.
- Data (updated daily) · First launched 2026-09-03 · Vietnam rating 135 · Charted in 11-08 of 1 stores
iOS · best category chart rank · by store VietnamBNData 2026-10-28 → 2026-11-08 (12 days, 12 observations). Lower rank is higher; gaps mean it wasn't charted that dayiOS · Rating count · Vietnam Data 2026-10-28 → 2026-11-08 (12 days, 12 observations). Apple doesn't publish download counts; rating growth is a proxy for downloads.
Monii is a budgeting app that Vietnamese indie developer Nguyễn Phúc published in Sep 3. It opens to a monthly calendar, where each day is shaded in a different intensity according to how much you spent, and it tells you how much you can still safely spend today. Over two months it climbed as high as #18 on the Vietnam App Store finance bestseller chart, with 129 ratings averaging 4.8 stars. The features aren't new and the scale is small. What's worth watching is how one person used short-form video in his native language, plus an interface built for screenshots, to carve out a spot in a category that was already crowded.
Oct 9 video
On Oct 9, the TikTok account @_nguyenphuc posted a video captioned "Lương ba cọc ba đồng nên lúc nào cũng phải ghi chép để tiết kiệm" (my pay is tiny, so I always have to write things down to save money). The bio reads "Coder nghiện startup" (a programmer addicted to startups), and by November it had only 106 followers. By Nov 6 this video had 157k views, 2,005 likes and 82 comments (TikTok, viewed 11-06).
The comments read almost like a demand survey:
- "app tên gì v ạ, mình tìm trên chplay ko thấy" (what's the app called? I can't find it on Google Play). This one got 11 replies, and several people were asking about the Android version;
- "Có tốn phí không ạ" (does it cost money?);
- "Có dùng chung 2 vợ chồng trên cùng 1 tkhoan đc k" (can a husband and wife share one account?);
- "Ko ghi lại thì ko biết tiền đi đâu, ghi lại sợ lên cơn đau tim mỗi lần nhìn tổng" (if you don't record it you don't know where the money went, but if you do, you're scared of a heart attack every time you look at the total);
- Several others posted their own calendar screenshots with the line "Mới có 10 ngày" (only 10 days so far).
The last point says the most: users were posting the app's interface in the comments as if it were a meme.
What it is
A lightweight app that only does "how much did I spend today." The store page calls it "the clean, visual, and intelligent money calendar":
- The main screen is a calendar, and each day's cell is shaded in light, medium or heavy tiers by spending (a heatmap). The colours can be adjusted;
- It calculates a "Safe Daily Spending Limit" and tells you how much you can still spend today;
- No sign-up, works offline, and doesn't connect to bank cards;
- Over time it added invoice scanning, Excel export, iCloud sync (9-07), voice entry (9-18), loan tracking and photo entry (10-03), and fund accounts (10-20). It shipped 14 versions in two months (App Store version history).
Revenue comes from the Pro subscription: monthly 59,000₫ (about $2.3), yearly 299,000₫ (about $11.5), lifetime 599,000₫ (about $23) (Vietnam App Store page). Face ID lock is also gated behind Pro, which drew two one-star reviews: "FaceID là bảo mật cho người dùng mà bắt dùng pro mới có" (Face ID is a protection for users, yet you have to buy Pro to get it, 10-29). The developer replied that it was built to make money and that Pro is needed to keep the app running. Getting flamed for this suggests the paywall is really biting users.
What the #18 bestseller spot is worth
The short answer: not much.
| Date | Vietnam finance bestseller chart | Vietnam cumulative rating |
|---|---|---|
| 10-28 | #42 | 100 |
| 11-01 | #104 | 103 |
| 11-02 | #19 | 106 |
| 11-03 | #28 | 113 |
| 11-05 | #18 | 121 |
| 11-06 | #36 | 124 |
App Store Vietnam storefront, 10-28 to 11-06. On the free chart it stayed between #130 and #201.
Its rank could jump dozens of places in a single day, which means only a few subscriptions per day, and each extra sale moves the rank noticeably. On the same day (11-06), the #11 app on the Vietnam finance bestseller chart had been listed only 11-03 and had 0 ratings, and #25 had just 2 ratings. The bar to reach the top 50 in this Vietnamese category is very low. Converting "#18 bestseller" into revenue, it is roughly a few sales a day, a few hundred dollars a month (estimate, unverified).
Ratings went from 10-28 to 11-06, adding 24 in total, with 11-03 peaking at 7 in a single day. It's climbing, but still single digits. The US store has only 3 ratings, and there's no Android version yet. Right now it's just a small app in Vietnam, just getting started.
Where users come from
Basically one developer running it:
- Shooting its own TikToks. Apart from 10-09, 10-04 "the simplest budgeting app I've ever used" got 8,693 views, 10-14 "asking my husband for money at home, so I have to track it in Monii" got 10,296 views, and the rest get a few hundred each. The themes are everyday money stress for young Vietnamese and new moms; the app is just a prop, and there are no feature demos (TikTok, 11-06).
- Asking questions on Threads. He posted on Threads: "What app do you use to track spending? Before, I used Monii. It's convenient, and most importantly, it's free." 313 likes, 37 replies. He also once said, "Vietnamese people are happy to spend money. They'll pay for something useful."
- Cold-start on Unikorn (Vietnam's Product Hunt): #4 for the day and #10 for the week in Sep 6.
- There may be some App Store search traffic too: the title includes the generic term "Money Calendar", and it supports 46 languages (inferred, no direct evidence).
No ad campaigns or press coverage found, and nobody is discussing it on X.
Who it's competing with
Vietnam's budgeting app market is crowded:
| Product | Vietnam rating | vs. Monii |
|---|---|---|
| Money Note (Japan's Komorebi, 2018) | 296k, #6 in Finance bestsellers | Also offline with a calendar view, but a plainer interface |
| Sổ Thu Chi MISA (local big player, 2014) | 45k, #2 bestseller | Full-featured ledger |
| Money Lover(2011) | 27k, #9 bestseller | Vietnam's oldest budgeting app |
| Rolly: AI Budget (Australia, 2024) | 13k, #4 bestseller | Built around budgeting through AI chat |
| CapMoney (Vietnamese indie, 2026-01) | 283, Top Grossing #7 | Photo-recognition expense logging |
| Nếp (Vietnamese indie, 2026-09-20) | 108 | Auto-logs by scanning VietQR; same timing and scale as Monii |
App Store Vietnam storefront, 11-06.
There are also a batch of Vietnamese indie budgeting apps like Sổ Thu Chi Bido, Sổ Xanh, iLoveMoney, and Cháy Túi, each with a few to a few hundred ratings, mostly released 9–October. Calendar-based expense tracking isn't Monii's invention either: the English app Dollarbird has been doing a "budget calendar" for nearly a decade.
So Monii isn't winning on features. It's winning on packaging: the calendar as the home screen, heatmap colors, a cute look, Vietnamese-language content about Vietnamese life, and free to start. The heatmap's real job is to make the videos look good and give users a reason to screenshot, so it's an amplifier, not a moat. The developer's earlier app Tích Chỉ (gold tracking, 488 ratings) has already been copied by name as "Tích Chỉ Vàng", so it's only a matter of time before Monii gets copied too.
If it were you
One-line verdict: worth a test, but don't copy the Vietnam version. What's worth copying is the playbook of a "general-purpose tool + localization + founder-made short dramas about everyday life," applied to a country where nobody has done it yet.
Who it's for: one or two people who can build an iOS app and naturally make short videos in a Southeast Asian or Latin American minor language (Indonesian, Thai, Filipino, Portuguese, Spanish), or indie devs already living in that country.
Who it's not for: anyone who wants meaningful subscription income. These markets have a fraction of the US and Europe's price per user, and a good bestseller rank doesn't mean good money. It's also not for people unwilling to appear on camera themselves, since nearly all the volume from this playbook comes from the founder's own videos.
How to do it:
- Do just one core thing: a monthly calendar colored by spending, plus "how much you can still spend today," so users can screenshot it from the first screen. Build it within two weeks.
- Price for the local market, with annual and lifetime plans up front. Don't lock "security" features like Face ID behind Pro. Monii's one-star reviews complain about exactly that, locking a "premium" feature.
- Validate on iOS first, but the comments will ask about Android, which Monii still doesn't have. That's your chance to do better. Shared household ledgers for couples also keep coming up in the comments.
How to get users: your own TikTok account, three to five posts a week, filming scenes locals instantly relate to, like "my salary is small, I have to track spending" or "asking my partner for money", with the app just a prop in the frame. End each video by asking viewers to share their own monthly calendar in the comments. For cold-start, list on local product sites (Vietnam has Unikorn; find the equivalent community in other countries), then post questions like "What app do you use to track spending?" on Threads.
Time window: I haven't seen anyone doing this outside Vietnam yet, and Monii itself hasn't gained traction in other countries (3 US ratings). Small apps like this get copied fast. Vietnam saw a wave of similar apps within two months, so the window is months, not years.
Signs you've misread this: (1) your videos in a new country have 20 posts and none pass 50k views, meaning the playbook depended on Phúc's own topic choices and luck rather than being repeatable; (2) Monii launches a version in 46 languages and takes off first in Indonesia and Thailand; (3) after two months, daily subscriptions are still single digits, meaning this category only works as a side business in low-price markets.
Data and sources
- Ratings, charts, and competitor figures: App Store Vietnam and US storefronts, 10-28 to 11-06.
- Pricing, version history, reviews, and developer replies: Monii's App Store Vietnam page, 11-06.
- TikTok videos and comment quotes: public videos from @_nguyenphuc, viewed 11-06; Threads: public posts from @_phucnguyen._.
- Unikorn: unikorn.vn/p/monii.
- Revenue is inferred from bestseller rank and the number of ratings on comparable apps. No public figures are available. I couldn't find any ad spend, but that doesn't mean there was none.
Research notes: competitor table, acquisition evidence, full research report
- Competitors
Name Where Launched Scale How it differs from this one Expense Tracker - Money Note(Komorebi) iOS 2018 Vietnam: 295,886 ratings, #6 in Finance bestsellers Also offline with a calendar view, but a plainer interface. Monii makes the calendar the main screen, with heatmap colors, a cute style, and safe-day spending. Sổ Thu Chi MISA iOS 2014 Vietnam: 45,452 ratings, #2 bestseller A local big player's heavyweight ledger. Monii is lighter and more emotionally designed. Money Lover iOS 2011 Vietnam: 26,740 ratings, #9 bestseller Long-established and full-featured. Monii only does "how much you spent today." Rolly: AI Budget iOS 2024-08 Vietnam: 13,045 ratings, #4 bestseller Expense logging through AI chat. Monii centers on the calendar. CapMoney iOS 2026-01 Vietnam: 283 ratings, #7 bestseller OCR photo-based logging with no calendar heatmap. Nếp - Sổ chi tiêu tự động iOS 2026-09-20 Vietnam: 108 ratings, 7 days +14 Auto-logs by scanning VietQR. Same timing and scale. Dollarbird - Budget Calendar iOS 2017 About 3,500 ratings in the US; not on the chart in Vietnam. English-language budget calendar prototype with forecasting and collaboration. Built-in expense logging in MoMo / Timo / BIDV. Big-company features Already around Huge user base. Automatically logs bank transactions, but has no calendar heatmap view. - Where users come from
- Verified Developer's own TikTok (@_nguyenphuc): 10-09 video 156,569 views / 2,005 likes / 82 comments, with many comments asking for the app name and an Android version. The other videos have 300–10,000 views (TikHub).
- Verified Threads: @_phucnguyen._ "What app do you use to track spending? Before, I used Monii", 313 likes / 37 replies
- Verified Unikorn.vn (Vietnam's Product Hunt): #4 for the day, #10 for the week, 2026-09-06
- Inferred App Store search / multiple languages: the title includes the generic term Money Calendar, 46 languages; no direct evidence
- Inferred Lifestyle creators recommending it organically: the recall reason cites 2,600+ likes on a single post; the corresponding video was not found
- Inferred Paid ads: not in the ad libraries; none found
Monii - Money Calendar (iOS 6803572087) research report
In one line: Vietnamese indie dev Nguyễn Phúc (an individual developer account, previously made the gold-tracking app "Tích Chỉ") launched a money-tracking app on 2026-09-03: one calendar per month, each day's cell colored by how much was spent (a heatmap), plus a "how much can I safely spend today" number. It has traction for two reasons: the Vietnam Finance Top Grossing bar is extremely low, and the dev himself posts "this is how I track my money"-style content in Vietnamese on TikTok and Threads, bringing his own traffic. The scale is tiny and it's Vietnam-only; almost nobody else knows about it. The calendar format itself isn't new (Money Note, Vietnam's most-rated expense app, already has a calendar view). What's different is the packaging: cute, heatmap, localized, free.
1. How to read the data card
- Vietnam only: 129 ratings on the Vietnam store, 4.8 stars; the US has just 3 ratings (iTunes lookup, 2026-11-06). The Bengali (bn) market that shows up in the card between 11-01 and 11-03 only appeared on the Finance Top Free chart for 3 days (#34 → #126 → #185), with 0 ratings (appstore.app_day).
- Rating growth: 100 ratings at 10-28, 124 at 11-06, 22 new in 7 days, peaking at 7 in a single day (11-03) (appstore.app_day). So the first 100 ratings came in over the 55 days after launch, about 2 a day on average; our database only started collecting on 10-28.
- Vietnam Finance Top Grossing (genre 6015): #42 (10-28) → dropped to #104 (11-01) → #19 (11-02) → #28 → #49 → #18 (11-05) → #36 (11-06). The Top Free chart stayed around #130–201 (appstore.chart_rank). The ranking jumps up and down, which suggests only a handful of subscriptions per day; each purchase visibly moves the position.
- Bar check: 11-06 In the Vietnam Finance Top Grossing chart, #11 is Accounted (11-03 release, 0 ratings), and #25 is "Sổ Tiền Hôm Nay" (2 ratings) (appstore.v_chart / app_profile). So getting into the top 50 in this category takes very little revenue. "#18 Top Grossing" doesn't translate into serious money here.
- Pricing: Monii Pro monthly ₫59,000 (about $2.3), yearly ₫299,000 (about $11.5), lifetime ₫599,000 (about $23) (Vietnam App Store page). FaceID lock is also behind Pro, and two 1-star reviews are complaining about it (10-29, 11-01). The developer replied, "I built this to make money, so you need Pro to keep the app going." That suggests the paywall is blocking a portion of users.
- Frequent updates: 14 versions in 2 months after launch (1.0.0 → 1.2.5). Features added over time: 9-07 invoice scanning + Excel export + iCloud sync, 9-18 voice entry, 10-03 loan tracking + photo entry, 10-20 funding accounts (App Store version history).
- The developer's other app: Tích Chỉ (personal gold tracking / gold prices, listed on 2026-03-09, 488 ratings, #50 on Vietnam Finance Top Grossing). The developer pinned a post on Threads saying "I was the first to build Tích Chỉ on iOS, and I'll expose anyone who copies it." A "Tích Chỉ Vàng" (Dat Ngo, listed on 10-13, #34 on the chart) already appears on the 11-06 Top Grossing chart.
2. Competitors
| Product | Where | Launched | Scale (Vietnam) | How Monii differs |
|---|---|---|---|---|
| Expense Tracker - Money Note (Komorebi, Japan) | iOS | 2018 | 295,886 ratings, Finance Top Grossing #6, +169 in the last 7 days | Also offline, no sign-up, has a calendar view, but the interface is a plain native iOS style; Monii makes the calendar the main screen, with a heatmap and a cute look |
| Sổ Thu Chi MISA(MISA) | iOS / Android | 2014 | 45,452 ratings, grossing #2 | An established local big-name, feature-rich and ledger-focused; runs official content ads on TikTok |
| Money Lover(Finsify) | iOS / Android | 2011 | 26,740 ratings, grossing #9 | Vietnam's longest-running expense app, feature-heavy |
| Rolly: AI Budget (Australia) | iOS | 2024 | 13,045 ratings, Top Grossing #4, +114 in the last 7 days | Focused on AI chat-based expense entry |
| CapMoney (Lam Le, Vietnamese individual) | iOS | 2026-01 | 283 ratings, grossing #7 | Focused on OCR photo entry, no calendar |
| Nếp - Automatic Expense Book (Le Thai Binh, Vietnamese individual) | iOS | 2026-09-20 | 108 ratings, +7 in the last 14 days | A Vietnamese indie app that emerged around the same time, focused on automatic entry by scanning VietQR; about the same scale as Monii |
| FastMoni / Wisepenny / SSMoney / Sổ Thu Chi Bido / Sổ Xanh / iLoveMoney / Cháy Túi and more | iOS | 2024–2026 | Each 0–338 ratings | A large wave of Vietnamese local indie expense apps: low barrier to entry, very similar to each other |
| Moni(moni.live) | iOS / web | 2026 | Not verified | Name differs by a single letter; focused on cashback, AI, and gold prices |
| Dollarbird - Budget Calendar | iOS / Android | 2017 | About 3,500 ratings worldwide (US), not on the Vietnam chart | The original "budget calendar" product, English-language, more about forecasting and collaboration |
| Tracking built into banks / wallets (MoMo, Timo, BIDV) | Big-company features | Already around | Huge user bases | Can auto-record bank transactions, but there's no "how much did I spend each day" calendar view; "tracking with MoMo / Timo" videos on Vietnamese TikTok have hundreds of thousands to over two million views |
Takeaway: neither the calendar nor the heatmap is Monii's invention, and Vietnam's local indie expense app market is already crowded. It doesn't win by having no competitors.
3. Where users come from
- The developer posts on TikTok himself (confirmed, the main channel): account @_nguyenphuc (bio "Coder nghiện startup", roughly "a programmer hooked on startups"; 106 followers, 33 videos). The best performer is 10-09's "Lương ba cọc ba đồng nên lúc nào cũng phải ghi chép để tiết kiệm" (meager salary, so you always have to track to save): 156,569 views, 2,005 likes, 82 comments. The comments keep asking "what's the app called," "can't find it on Android," "is it paid," "can a couple share one account," and some people post their own calendar screenshots ("only 10 days in"). Other videos (9-10, 9-17, 10-04, 10-14, etc.) get 300–10,000 views each (TikHub, 2026-11-06). The topics are everyday pain-point skits ("asking my husband for money at home, so I need Monii to keep it clear"), not feature demos.
- Threads (confirmed): @_phucnguyen._ posted "What app do you friends on Threads use to track money? Me before: Monii, because it's convenient, and most importantly, it's free," which got 313 likes and 37 replies. He has also posted "Vietnamese people are willing to spend; if it's useful, they'll pay" (Jina crawl of threads.com). 11-04 He posted the same copy on TikTok too.
- Unikorn.vn (Vietnam's Product Hunt, confirmed): listed on 2026-09-06, #4 for the day, #10 for the week (unikorn.vn/p/monii). This was the first wave of the cold start.
- Store search (inferred): the app supports 46 languages and 9 interface languages, and its title includes the generic term "Money Calendar"; the "people also bought" section on the Vietnam store lists it alongside CapMoney, SSMoney, and similar apps. No direct evidence.
- Responding to reviews / possible review prompts (partly confirmed): the developer replies to every positive review with "Thanks for the support, wishing you lots of savings 😍". 4.8 stars is on the high side for an app that gets criticized for its paywall, but I found no evidence of an in-app prompt asking for reviews.
- Not found: Meta / TikTok ads (the ad library doesn't index this product; not finding it doesn't mean it wasn't run), press coverage, discussion on X (x-radar returns nothing in the last 60 days). The data card's recall reason says "organic recommendations from lifestyle creators, 2,600+ likes per post," but I could not verify the matching video. A "Chi tiêu" video from the same period with 2,549 likes (xom_lavenda, 11-02) is from a family-life skit account, and I can't confirm whether it mentions Monii.
4. Why it took off
- The Vietnam Finance Top Grossing bar is extremely low: a few subscriptions are enough to reach the top 20, so the chart position amplifies a very small app.
- The founder appears on camera to drive traffic, and picks pain-point topics: skits about "low pay, need to track" and "asking the husband for money," which resonate with young Vietnamese and mothers; one 150k-view video drove a wave of downloads. The comments ask for download links, which suggests the content matches the product.
- The calendar heatmap is made for screenshots: you can see a month's spending at a glance, and commenters post screenshots of theirs. The heatmap is itself shareable material.
- Positioned as "light": positive reviews say "I just want to record what I spent today" and "cute and useful," separating it from heavy ledger apps like MISA and Money Lover. No sign-up, fully offline, no bank card linking.
- Fast iteration: 14 versions in 2 months; voice, photo, invoice, and loan features that other Vietnamese apps already have were added quickly.
- Free and useful, with the paywall at key features: FaceID and some advanced features are locked behind Pro; yearly / lifetime prices are set for Vietnamese spending levels (a fraction of US/EU peers' ¥/$ pricing).
5. Differentiation
Monii's differentiation is in experience and packaging: the main screen is a calendar, each day is heat-colored by spending, plus "how much you can safely spend each day," and it's cute, localized, and free. The features themselves aren't unique: Money Note has had a calendar view for a long time and has earned nearly 300k ratings in Vietnam; Dollarbird has been doing a "budget calendar" for years; Deco Budget and others offer safe daily spending. It took off mainly because the founder uses short videos to tell a Vietnamese person's expense-tracking story, combined with the low Vietnam Top Grossing bar. The differentiation helps the videos look good and makes screenshots easy to share, but it isn't a moat.
6. How visible it is
Still barely known. No press coverage, no discussion on X, revenue not public (the developer has only said on Threads that "Vietnamese people will pay"). The only visible traces are 1 reviews on Unikorn and the developer's own TikTok and Threads. No one has specifically copied Monii, but Vietnamese local indie expense apps are already numerous (Nếp, Sổ Thu Chi Bido, Sổ Xanh, iLoveMoney, Cháy Túi, and others, mostly appearing in 2026 9–October). The developer's previous app, Tích Chỉ, has already been copied by name.
7. What to borrow
- Take a globally common tool format (calendar / heatmap expense tracking) and localize it for a small-language market: local currency, local language, local price points.
- Sell subscriptions in countries and categories with low bars to the top charts; but convert chart positions back to actual revenue before judging.
- The founder films everyday pain-point skits himself, using the app as a prop rather than doing feature demos; also engages on Threads with questions like "what app do you use?"
- Make the core screen itself shareable as a screenshot.
8. Still unclear
- Actual revenue: a Top Grossing position of #18–104 in Vietnam probably corresponds to a handful of subscriptions per day; the exact amount can't be verified.
- Which video the recall reason's "lifestyle creator 2,600+ likes recommendation" refers to.
- Whether ads were run (Apple Search Ads, Meta, TikTok Vietnam).
- Whether it can be replicated elsewhere: the US has only 3 ratings so far, multi-language versions haven't gained traction, and there's still no Android version (the comments keep asking).
Sources
- appstore database (agent-im: app_profile / app_day / chart_rank / v_chart, 2026-10-28 to 2026-11-06)
- App Store Vietnam page apps.apple.com/vn/app/id6803572087 (pricing, version history, reviews and developer replies)
- iTunes lookup API(vn / us,2026-11-06)
- TikTok @_nguyenphuc videos and comments on 10-09 videos (TikHub, video id 7694661529857281287)
- Threads www.threads.com/@_phucnguyen._, www.threads.com/@_phucnguyen._/post/Devnqr5ILXn
- Unikorn unikorn.vn/p/monii, /updates
- Developer's Facebook www.facebook.com/juno.zdev/ (Chợ Flatsome founder), website junozdev.io.vn
- x-radar search for "Monii" in the last 60 days (no relevant results)