Three weeks, 850k installs, 397 ratings: a Vietnamese PDF tool, and an ad-buying pipeline that still moves the needle
What it is A free phone tool that opens all kinds of documents, turns photos and Office files into PDFs, and merges and signs them. It makes money from ads.
Why it took off The team bought installs with on-off ad bursts in cheap markets like Eastern Europe and Southeast Asia, pushing it up the productivity category charts, where the bar is low. Once installed, it sits in the system "open file with" menu, so every file opened is an ad impression, and the math works.
CHow you could play it Don't build the #171 PDF reader. Copy the pipeline (a universal must-have utility + a system open-with entry point + ad-only monetization + cheap-market ad buying to climb category charts), and apply it to a tool niche that isn't crowded yet. The prerequisite: you know how to run Google App Campaigns and have a budget you can lose for a few weeks.
- Data (updated daily) · first launch 2026-10-13 · 11-07 installs 855,349
Android · Total installs worldwide Data 2026-10-29 → 2026-11-07 (10 days, 10 observations). Google's detail page only refreshes install counts every other day, so a flat day doesn't mean nobody installed.Android · Ratings count (cumulative) Data 2026-11-05 → 2026-11-07 (3 days, 3 observations)
A small Vietnamese team launched a PDF converter called Reampo on Google Play in Oct 13. In three weeks it got 855k installs and cracked the top ten of the productivity charts in Poland, Romania and Thailand. The product is no different from dozens of others, and almost all its volume was bought. What's worth looking at is why this playbook still pays, and how many people are already ahead of you if you want to try it.
A 70-year-old Thai user left a comment under a PDF tool
In Oct 28, a Thai user gave Reampo's store page five stars and wrote their full name, saying "I'm 70 years old, I like watching movies and TV dramas, I have no experience with this, sorry". Someone in Romania wrote their birth date and home address in the review box; another wrote "I already have 5 PDF apps, which one is better? I want Google Play to answer me"; and someone said "I don't have Douyin anymore" (Google Play reviews, 10-20 to 11-05).
These people weren't looking for a PDF tool. They saw an ad inside a game or video app, tapped install, and after installing weren't quite sure what it was. That's where Reampo's users come from: ads.
What it is
A phone tool that opens any file and also turns things into PDFs: photos, album images, paper documents scanned to PDF; Word / Excel / PPT / text to PDF; merging, reordering pages, annotating, signing, and password protecting. The landing page reads "5 file types open, 6 ways to make a PDF, 13 languages, 0 upload, all processed on your phone."
Free, no in-app purchases, with ads. The version has been stuck at 1.0.4 and hasn't been updated since Oct 20.
The developer DongRuaLabs has only two apps. The other is a TV remote app, RemoteTV, with just over two hundred installs, which looks like the same playbook being tested on a second category. The contact email and privacy policy both sit under the domain dong.vc, the personal site of an executive at Funtap, a Vietnamese mobile game publisher, who handles investment and studio incubation. The inference that the team comes from Vietnam's mobile game ad-buying circle rests only on the domain match; it hasn't been verified.
How the volume came in: an on-off curve
Cumulative installs (early days are third-party estimates; from 10-29 onward it's Google Play's public numbers):
| Date | Total installs | Notes |
|---|---|---|
| 10-16 | About 7,600 | Day 3 after launch |
| 10-21 | About 70k | About 57k added that day |
| 10-26 | About 380k | About 175k added that day |
| 10-27~28 | About 390k | Almost flat for two days, about a hundred a day |
| 10-31 | 600k | |
| 11-03 | 740k | |
| 11-06 | 855k | 465k added in 7 days |
An organically growing app's curve is smooth. This one jumps in steps: one day it adds a hundred-plus thousand, the next it almost stops, then it climbs again. That's what it looks like when ad budgets are switched on and off and bids are adjusted (inference, high confidence; I found no ads for it in the Meta ad library, the closest match is Google's own App Campaigns, placing volume across Play and partner apps).
Other signals fit too:
- Very few ratings. 855k installs, 397 ratings, roughly one rating per 2,200 installs. Users who came looking for it on their own wouldn't be this silent.
- Only two rating levels. 317 five-star and 79 one-star; two to four stars are 0 (Google Play, 11-06). One one-star reads "Ads never stop, useless app"; a Romanian user complained "not great, why do you keep pushing me", likely referring to the rating prompt that keeps popping up in the app.
- It only charts in cheap markets. 11-06 It ranks in 15 storefronts' productivity free charts, best at #17 in Poland, #50 in India, #72 in Thailand; 10-29 once reached #7 in Thailand and #9 in Poland, and #54 on Poland's overall chart; it briefly hit #1 in Romania's productivity chart. All are Eastern European and Southeast Asian markets where installs are cheap.
- No noise outside the store. Searches for "Reampo" on TikTok and X return 0 results each, with no media coverage. The only web presence is automatic pages from app analytics sites.
Store search helps too: the title, package name (pdf.reader.converter.tools) and description are stuffed with photo to PDF, image to PDF, scan to PDF, DOC to PDF, localized into 13 languages. Once it reaches the category charts, the chart position itself brings a bit of organic volume.
Where the money comes from
Entirely ad-driven. What makes the math work is an inconspicuous permission: it requests "manage all files". Once installed, whenever a PDF, Word or Excel file is opened on the phone, the system asks which app to open it with, and it's in the list. Every time a user opens a file, that's an ad impression. A Thai commenter wrote "Suddenly so many files popped up, it's scary", which is exactly it surfacing every document on the phone.
Public channels don't reveal what each install costs or how much each user earns. But a team willing to push 850k installs in three weeks, pausing and resuming, must be netting positive by their own math (inference).
Who it's competing with: 170 rivals already on this street
This isn't an empty market. Since July 2026, 170 newly launched Google Play apps have PDF or document reading in their names; 45 have passed 500k installs and 25 have passed 1M. Together these 170 apps added about 8.5M installs in the last 7 days (Google Play public data, 11-06). 11-06 In Poland's productivity free chart, 20 of the top 8 are PDF readers, and 34 of the top 100.
| Competitors | Scale | Its relationship to Reampo |
|---|---|---|
| PDF Reader & Document Viewer(QTStudio) | Launched the same day as 10-13, now at 7.11M installs | Same play, 8× its volume |
| PDF ProX(Office Suite Pro) | 33M, +1.25M in 7 days | Same playbook, running for over a year |
| Readdock - PDF Tools(Innovate AI) | 11.4M, +1.02M in 7 days | Right next to it on Poland and Romania charts |
| Image to PDF(Simple Design) | 100M | Same photo-to-PDF plus ads, entrenched incumbent |
| Adobe Acrobat, WPS, CamScanner | 5–900M each | Brands and subscriptions, a different business |
| Files by Google, the built-in Android 15 PDF viewer | System level | Free with no ads, absorbing part of the "I just want to open this" demand |
| iLovePDF, Smallpdf, PDF24 | Leading web-based tools | Requires uploading files; desktop users go here |
At 855k installs, Reampo is only mid-pack among these new apps. Its differences (calling itself a converter rather than a reader, a brand name, emphasizing no upload) are things most rivals also have, so they aren't why it broke through.
If it were you
In one line: This is an ad-buying business. Anyone can build the product; the contest is over who can buy users who keep opening files at the lowest price. 170 peers have already proven it makes money, and also proven the street is crowded.
Who it suits: teams that have already run tool and hyper-casual game campaigns on Google App Campaigns or ad networks, have a budget they can lose for several weeks (tens of thousands of dollars at least), and understand AdMob placements and mediation waterfalls. Teams in Vietnam, India, Turkey, where costs are low and batch tool-making is routine, have the edge.
Who it doesn't suit: indie developers who've never bought ads and hope for organic store traffic won't get ranked on this street. Anyone counting on "better quality" to break out will face users who can't tell them apart from the sixth PDF app. Anyone aiming for subscriptions won't get paid by this audience.
How to do it: Don't build the #171 PDF reader. The pipeline behind it is what's worth learning: a universal must-have tool, hooked into the system's open-with, ad-only monetization, a brand name plus multilingual landing pages plus a free privacy policy page, enough to validate a category in three weeks. Apply the same pipeline to a category that isn't crowded yet (beyond files, scanning, TV remotes, and cleaners), which beats fighting for a spot in PDFs.
How to acquire users: Google App Campaigns, starting in countries where the category charts are easy to enter, like Poland, Romania, Thailand and the Philippines, aiming for the top 20 of the productivity chart before riding its organic traffic; stack keywords per language on the store page.
When to get in: There's no clear deadline, the niche will be there for a while. But Android's built-in PDF viewer keeps improving, so fewer users just want to "open a file", and retention will increasingly depend on conversion, merging and signing, things the system doesn't do.
Signs you've misread it: if installs flatline within a week or two of Reampo stopping its spend and its chart rankings all drop, that means users aren't sticking and the math doesn't hold. Or, if among these 170 new PDF apps the 45 that passed 500k installs mostly stop updating or get pulled in the next month, the people on this street have started cutting losses and leaving.
Research notes: competitor table, acquisition evidence, full research report
- Competitors
Name Where Launched Scale How it differs from this one Adobe Acrobat Reader Android 2010 940M installs Big brands, in-app purchase subscriptions; Reampo is free, ad-monetized, and runs on paid acquisition CamScanner Android 2010 580M installs Scan-focused with paid subscriptions; Reampo is broader in features and has no in-app purchases Image to PDF - PDF Maker(Simple Design) Android 2020-12 100M installs Same photo-to-PDF plus ads, entrenched incumbent; Reampo is a new package climbing charts through paid acquisition Readdock - PDF Tools(Innovate AI) Android 2025-06 11.4M installs, +1.02M in 7 days Same playbook at larger scale, sitting right next to Reampo on the Romania and Poland charts PDF ProX(Office Suite Pro) Android 2025-04 33M installs, +1.25M in 7 days Same playbook, positioned around reading and editing; Reampo focuses on conversion and creation PDF Reader & Document Viewer(QTStudio) Android 2026-10-13 7.11M installs Launched the same day with 8 times the volume, showing Reampo's results are only mid-pack in its category Files by Google / Android built-in PDF viewer / Google Drive scan Big-company features Years System level Free and ad-free, but features are scattered; Reampo puts convert, merge, and sign in one app iLovePDF / Smallpdf / PDF24 Web 2010 era Leading web-based tools Web tools require uploading files; Reampo stresses 0 uploads and all processing on the phone - Where users come from
- Inferred paid acquisition (likely Google App Campaigns / ad networks): step-function curve (10-26 single day +175k, 10-27~28 days up about 124); install-to-rating ratio about 2,200:1; charted only in low-cost traffic tiers; no records in the Meta ad library, Google ad library not tracked
- Confirmed store search / ASO: title, package name, and description stuffed with PDF converter / photo to PDF / scan to PDF / DOC to PDF; localized into 13 languages
- Confirmed chart exposure with organic traffic: Poland Productivity Top Free 9–22, Thailand 7, Romania Productivity #1 (appfigures), Poland overall 54
- Confirmed system "Open with" entry: requests MANAGE_EXTERNAL_STORAGE, can open PDF/DOC/XLS/PPT/TXT
- Inferred rating prompts pushing good reviews: rating distribution 1★77 / 2–4★0 / 5★311; Romanian reviews complain "why does it keep nagging"
- Inferred TikTok / X / media: TikHub and x-radar both return 0 results for Reampo
Why Reampo: PDF Converter & Maker (com.pdf.reader.converter.tools) managed to run
Channel Google Play · Developer DongRuaLabs (Vietnam) · Store launch 2026-10-13 · Research day 2026-11-06
Bottom line
It isn't an app that grew on product or word of mouth. It's another paid-acquisition sample in the batch-PDF reader/converter category on Google Play in the second half of 2026. A small Vietnamese team (most likely part of the venture-build setup of Funtap-linked investor Dong Nguyen Xuan) used a competent general-purpose PDF tool, a brand name, and multilingual landing pages, then ran UAC-style stepped scaling in cheap-traffic regions like Poland, Romania, India, and Thailand, relying on ad monetization to pay back. It differs little from the 170 other new PDF apps of the same period. The reason it worked is "acquisition plus existing demand in the category," not differentiation.
1. Data (our googleplay library, 2026-11-06)
- Global cumulative installs 855,349; 7 days of new installs 465,018; only 389 ratings (about 2,200 installs per 1 ratings), average score 4.2.
- Curve since launch (estimated by AppstoreSpy,
app_day_ext): 10-16 about 7.6k → 10-20 about 17k → 10-21 daily about +57k → 10-25 about 210k → 10-26 daily about +175k → 10-28 390k → 10-31 600k → 11-03 740k → 11-06 855k. A week after launch, it scaled in sudden steps, then nearly stalled during 10-27~28 (daily adds about 124), and then recovered to 2.5–70k a day. This on/off curve is the classic shape of paid acquisition (budgets turned on and off, bids adjusted), not the smooth curve of organic word of mouth. - Charts: only the Productivity Top Free chart. 11-06 charted in 15 regions: Poland 17, India 50, Thailand 72, France 76, Germany 77, Philippines 90 and more; 10-29 once reached Thailand 7 and Poland 9, and Poland overall 54. Outside our database, appfigures shows it at #1 on Romania's Productivity Top Free chart and in the top 10 overall in Bosnia and Herzegovina (appfigures page, read via 2026-11-06).
- Monetization: no in-app purchases (offers_iap = false), marked as containing ads (ad_supported = true), so it is purely ad-monetized.
- No updates since version 1.0.4,2026-10-20.
- Rating distribution [1★ 77, 2–4★ 0, 5★ 311] (Play listing, 11-06). The middle tier is 0, so the ratings are polarized, which looks like a rating prompt steering people to five stars plus one-star complaints about ads.
2. Competitors: this is an extremely crowded red ocean
In our database (googleplay, 11-06):
- Apps launched since 2026-07 with PDF or document reader in the title: 170 in total, of which 45 have passed 500k installs and 25 have passed 1M, adding about 8.51M installs combined in 7 days. Reampo (855k) is only mid-tier.
- On the 11-06 top 100 free charts in productivity across storefronts, apps with PDF in the title: Poland 34, Thailand 32, France 27, India 23, Germany 23, UK 21, US 17. In Poland's productivity top 20, 8 are PDF readers (Trusted Mobile Utilities, Animeni, Office Suite Pro, One Text Initiative, Readdock, SMI Team, Alpha Black Car Services, P & L Studio, and others). Reampo ranks 17.
- Typical similar apps that scaled in the same period: Readdock - PDF Tools (Innovate AI, 2025-611M, +1.02M in 7 days), PDF ProX (Office Suite Pro, 2025-433M, +1.25M in 7 days), PDF Reader & Document Viewer (QTStudio, launched the same day as Reampo, now 10-13 7.11M), two scanners from Radiant Retail LLC (2026-08/09, 190–2.8M each), PDF Pilot (Suffron, 2026-9.73M), PDF Reader Viewer - Tools (HOSENR DEV, 2026-9.51M).
- Established players: Adobe Acrobat Reader (940M), WPS Office (830M), CamScanner (580M), PDF Reader - Easy PDF (QR Code Scanner., 430M), Image to PDF (Simple Design, 100M), Adobe Scan (260M).
- Big-tech bundled options: Google Drive / Files by Google includes PDF viewing, Android 15+ has a built-in system PDF viewer, Google Drive has scanning, and Samsung Notes, Microsoft Word, and Lens can also export PDFs.
- Web: iLovePDF, Smallpdf, PDF24, Adobe Acrobat Online (search results are full of free PDF converters).
3. Growth tactics
- Paid acquisition (inferred, strong signal, not directly seen in an ad library): the curve is stepped on/off (two single-day jumps of +5~170k around 10-21 and 10-26, with 10-27~28 almost 0); the chart regions are cheap-CPI Eastern Europe (Poland, Romania, Bosnia), South and Southeast Asia (India, Thailand, Philippines), and Latin America; the rating-to-install ratio 1:2,200 is far below apps that grow organically; review quality is very low ("Wait a minute, I'll be right back.", "Nu mai am Tic-toc", "Am 5 aplicații PDF care îi mai buna?", meaning users already have 5 PDF apps). This is the standard playbook in this category: Google App Campaigns (UAC) or ad-network traffic swaps, with AdMob interstitials paying it back.
- Our Meta ad library (metaads) has no ads pointing to this package name. The Google ad library (googleads) only tracks a watchlist, and this app isn't on it, so the paid channel can't be directly confirmed. Not finding ads doesn't mean there were none. Google UAC inside Play best matches the curve's shape.
- Store search / ASO: the title and description are stuffed with keywords (PDF converter, PDF maker, photo to PDF, image to PDF, scan to PDF, DOC to PDF), and the package name
pdf.reader.converter.toolsis also a keyword string; localized into 13 languages, with localized titles for Poland and others. - System "Open with" entry: requests MANAGE_EXTERNAL_STORAGE and can open PDF/DOC/XLS/PPT/TXT. After installing, it shows up in the open-with list, which brings retention and ad impressions. This is the core reason PDF reader apps can pay back.
- Rating prompts: the middle star tier is 0, and a Romanian review says "not very good, why do you keep pushing" (nu prea bună de ce insistați atit), suggesting frequent rating prompts inside the app.
- Content / social: nothing on TikTok (TikHub search for "Reampo" returns 0 results) or X (x-radar returns 0 results). Only automated aggregator pages like AppBrain, Apptopia, Similarweb, and CNET download listings exist. No media coverage.
4. Team background
- Developer DongRuaLabs has only 2 apps on Play: Reampo and RemoteTV: TV Remote & Cast (com.remote.tv.control, only 238 installs). The same "general tool plus brand name" playbook is being tested on a second category.
- Contact email [email protected], privacy policy hosted at sites.google.com/dong.vc, landing page reampo-pdf.netlify.app.
- dong.vc is the personal site of Dong Nguyen Xuan, head of corporate development at Funtap (a leading Vietnamese mobile game publisher), in charge of "investment, acquisitions, and venture-building game studios," and a partner at VIC Partners. Inference: Reampo is a project by someone named Viet Anh in his circle (the email uses his domain), or a small studio from his venture-build setup. The "tool app acquisition plus ad monetization" model is exactly what Vietnamese teams are good at (many of the Vietnamese hyper-casual and utility developers with netlify landing pages in our database belong to the same ecosystem). Team relationship not verified.
5. Differentiation
- On the product side, it is positioned as a "converter/maker" (photo to PDF, Office to PDF, merge, sign, encrypt, annotate) rather than a "reader"; the landing page stresses "0 uploads, all processing on the phone" and "13 languages"; it uses the brand name Reampo instead of a pure keyword title.
- But these features are nearly all offered by similar apps (Image to PDF, Readdock, PDF ProX, and CamScanner all do image-to-PDF, merge, and sign). Differentiation is weak and not why it worked. It worked on acquisition budget, the steady demand to "open or make a PDF" in the category, and ad monetization that made the numbers work.
6. Visibility
- Few people know about it: no public revenue, no media, X, or TikTok discussion, and it only appears on third-party chart aggregators. But the "PDF tool acquisition" category itself is already packed with players (the 170 new apps above), so it is not a blue ocean.
7. What to borrow
- Cheap-traffic regions (Eastern Europe, South and Southeast Asia, Latin America) plus Productivity charts: PDF apps can break into the top 20 in these regions at low entry cost, and charting can bring some organic traffic.
- A payback structure of "universal must-have utility + system open-method entry point + ad monetization": one product, 3 weeks, 850k installs, shows this UAC pipeline still works.
- Brand name plus multilingual landing pages plus a Google Sites privacy policy, a light-asset setup that can be quickly copied to a second category (RemoteTV).
8. Uncertain
- Specific paid channels (Google UAC / other ad networks / traffic swaps), CPI, and ARPU are unverified. The Meta library shows nothing.
- The link to Funtap / Dong Nguyen Xuan is inferred only from the email domain.
- Retention is unknown; whether installs fall back after scaling stops is unknown.
- The reason the middle rating tier is 0 (rating prompts or fake reviews) is unverified.
Sources
- Our library: googleplay (app, app_day, app_day_ext [AppstoreSpy estimates], chart_rank, app_profile, 2026-10-29~11-06); metaads (app_link, ad, no results); googleads (watch, adv_app, creative, no results).
- Play store page play.google.com/store/apps/details?id=com.pdf.reader.convert…; developer page play.google.com/store/apps/developer?id=DongRuaLabs; Play reviews (google-play-scraper, us/pl/in/ro/fr, 2026-11-06).
- Landing page reampo-pdf.netlify.app/?lang=en; privacy policy sites.google.com/dong.vc/pdf-2-privacy-policy/home
- dong.vc/ (Dong Nguyen Xuan's personal site)
- appfigures Romania Productivity chart appfigures.com/top-apps/google-play/romania/productivity; Bosnia & Herzegovina overall chart appfigures.com/top-apps/google-play/bosnia-and-herzegovina/t… (search snippet)
- AppBrain developer page www.appbrain.com/dev/DongRuaLabs/ (search snippet: 2 apps, about 700k installs)
- TikHub search for "Reampo": 0 posts; x-radar search for "Reampo": 0 posts (2026-11-06).