Comparison

Sustainability Rewards vs UnDoubt

Price, ratings, monetisation and update history for both apps, side by side β€” with what reviewers say about each.

Head to head
About

Sustainability Rewards

Features
Read full description

Sustainability Rewards is an engagement program, offering a gateway to improve sustainable and wellbeing behaviours at the University of Edinburgh through a wide range of fun activities. With this app, you will be able to earn Green Points for your actions under key themes relating to sustainability and wellbeing. You can make submissions or opt into weekly activities to earn Green Points, climb the leader board and win vouchers.

About

UnDoubt

Features
Read full description

UnDoubt is a simple, person-first verification app built on secure cryptography. It helps you confirm who you’re really communicating with by verifying requests in real time, before risky actions are taken. Real-time Verification 
Instantly authenticate who you are interacting with across voice, video, email or text. UnDoubt is your first line of defence against voice spoofing, AI impersonation, and online scams. Verify Before You Act 
Verify requests in real time before sharing information, sending money, clicking a link, or granting access. Simple and Intuitive Designed for real people, not security experts. Setup takes minutes, verification takes seconds, and the app stays out of your way until you need it. Privacy First 
Your personal information isn’t shared. Verifications happen privately without tracking or data harvesting. Grow Your Trusted Network See which contacts already use UnDoubt and verify them instantly. Invite others via a link when you need certainty, not assumptions. Free to Use UnDoubt is free to help protect you and the people who matter most. Optional premium features may be introduced later, but the core experience will always remain free. Terms of use: https://undoubt.co.uk/terms/ Privacy policy: https://undoubt.co.uk/privacy/

Screenshots

Sustainability Rewards4 screens
UnDoubt4 screens

Verdict

The call

The clearest difference is update cadence: UnDoubt at every 3 weeks against Sustainability Rewards's every 2 months. On price, ads, in-app purchases 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

CostPrice Β· In-app purchases Β· Ads Β· Monetization

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

UpkeepUpdate frequency

Sustainability Rewards ships an update every 2 months, UnDoubt every 3 weeks. The most recent releases landed on October 27, 2026 and October 28, 2026 respectively.

Scorecard1 real difference Β· 5 level
Sustainability Rewards versus UnDoubt: the parameters behind the verdict, then further details
ParameterSustainability RewardsUnDoubt
PriceFreeFree
Update frequencyEvery 2 monthsEvery 3 weeks β€” better
AdsNoNo
In-app purchasesNoNo
DevicesiPhone, iPad, iPod β€” betteriPhone, iPod
Requires iOS15.115.1
Further details β€” not scored
Size66 MB85 MB
Age rating4+4+
DeveloperGreen Rewards LtdLastingAsset LIMITED

In-app purchases

None

Sustainability Rewards

No in-app purchases

None

UnDoubt

No in-app purchases

Questions

Is Sustainability Rewards free?
Sustainability Rewards is free to download, with no in-app purchases.
Is UnDoubt free?
UnDoubt is free to download, with no in-app purchases.
Do Sustainability Rewards or UnDoubt have ads?
Neither Sustainability Rewards nor UnDoubt shows ads.
Which is updated more often, Sustainability Rewards or UnDoubt?
Sustainability Rewards ships an update every 2 months, and UnDoubt every 3 weeks. Most recently, Sustainability Rewards was updated on October 27, 2026 and UnDoubt on October 28, 2026.

Other comparisons