UDWriter vs BottleChallenge
Price, ratings, monetisation and update history for both apps, side by side β with what reviewers say about each.
UDWriter
A handwriting memo app designed with Universal Design principles for intuitive use. Offers three color options and a simple swipe gesture to clear the screen. Accessible for all users from the first use.
- Universal Design principles
- Handwriting memo functionality
- Select 3 colors
- Swipe to clear all
- Intuitive for all users
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"We got gold prize in IAUD Award Communication Design Category." This is a application of "hand writing memo" that is based on Universal Design. - Select 3 colors. - Swipe left on the corner, clear all. - For the first time, everyone can use this. URL Scheme is udwriter://
BottleChallenge
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Every time you refill your bottle instead of buying a new plastic one, something small but real happens. Less plastic to carry, less money spent. And with BottleChallenge, you actually get rewarded for it. Find free water near you The map shows refill points around you: cafes, restaurants, museums, gyms, and other venues that offer free tap water to anyone who asks. Updated by the community, so it keeps growing wherever you go. Earn real rewards Every refill earns you EcoDrops. Collect enough and redeem them for cinema tickets, theater and museum entries, concert passes, and special offers from local venues. The more you refill, the more you unlock. Track your refills BottleChallenge counts your refills and shows how many half-litre bottles of water you've filled. Share it or just enjoy watching the number grow. Scan and collect At participating venues, tap the NFC tag to instantly log your refill and earn EcoDrops on the spot. No manual input needed. Build the network Know a cafe or gym that offers free water but isn't on the map yet? Add it, upload a photo, and make it easier for everyone else to find. The network grows with every contribution. BottleChallenge is a free nonprofit app by BrainGreen Foundation. No ads, no subscriptions, just a community of people who believe that small habits, done consistently, actually change things. Download BottleChallenge. Refill. Earn. Repeat.
Screenshots
Verdict
The clearest difference is in-app purchases: BottleChallenge at none against UDWriter's 2. BottleChallenge also leads on update cadence (monthly vs every 2 months). UDWriter's advantage is iOS requirement (12.0 vs 15.1). On price, ads and device support there is nothing between them.
Scored on Price Β· Rating Β· Positive reviews Β· Number of ratings Β· Update frequency Β· Ads Β· In-app purchases Β· Monetization Β· Best chart rank Β· Devices Β· Requires iOS
Both are free to download. UDWriter sells 2 one-off in-app purchases. BottleChallenge asks for nothing beyond the download.
UDWriter ships an update every 2 months, BottleChallenge monthly. The most recent releases landed on October 12, 2026 and October 7, 2026 respectively.
| Parameter | UDWriter | BottleChallenge |
|---|---|---|
| Price | Free | Free |
| Positive reviews | 37.5% of reviews | β |
| Update frequency | Every 2 months | Monthly β better |
| Ads | No | No |
| In-app purchases | Yes | No β better |
| Monetization | Free with in-app purchases | β |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Requires iOS | 12.0 β better | 15.1 |
| Further details β not scored | ||
| Size | 10 MB | 49 MB |
| Age rating | 4+ | 4+ |
| Developer | Shamrock Records, Inc. | FUNDACJA BRAINGREEN |
In-app purchases
UDWriter
- Development Support + Logo on/off option$2.99
- Input Text by Using Speech Recognition$4.99
BottleChallenge
No in-app purchases
Questions
Is UDWriter free?
Is BottleChallenge free?
Do UDWriter or BottleChallenge have ads?
Which is updated more often, UDWriter or BottleChallenge?
Other comparisons
