Searching for apps that will run on an original iPhone – excluding apps that will not run on iOS 3.1.3 Apps for an old iPhone

I'd like to seek and find apps that will work on iOS 3.1.3 – without wasting time browsing apps that will not. And without a jailbreak. 

Apple's App Store appears to lack this capability – no filtering out of incompatible apps, even when using the Store on the handset. 

I found one answer … additional answers will be greatly appreciated. 

Thanks

Background

VintApps 3.1.3 might have been ideal. I never tried it. 

There's an iOS category at MacUpdate but the filters are nothing like what's required. 

Note

I'll use my first generation iPhone for as long as it continues to work as well as it does. So please, no answers that suggest an alternative iPhone.
Seeking an alternative to VintApps 3.1.3 led me to older Apps – MacRumors Forums (2013-11-05), there's a link to an Apple Club article: 

Finding iOS Apps Compatible with Older Devices

First impressions: useful, US-oriented. 

Adapted from what's there: I could use a Google UK search, such as the one below, as a basis for finding compatible apps in the UK App Store: 

https://www.google.co.uk/search?q=site%3Aitunes.apple.com%2Fgb%2F%20%22requires%20ios%202.0%7C2.1%7C2.2%7C3.0%7C3.1%22

… for example, a search for carshare-related apps.



Still, I'd prefer an app – ideally for OS X – with a smart user interface.