Answer 1

first 𝐊𝐢𝐢𝐛𝐨 𝐆𝐡𝐚𝐲𝐚𝐥 don't launch it to Google browser stick with launching through SoloLearn app - no 404

Answer 2

David Carroll
I believe it's a referrer url tracking parameter. It's generated only for links shared from the app--which signify someone used/accessed the link shared via the app.
The site has a similar url structure for discussions links. Just with added title in link without added ?ref=app.
https://www.sololearn.com/Discuss/2315620/solved-page-not-found-problem
Vs https://www.sololearn.com/Discuss/2315620/

Answer 3

Code Crasher Android supports opening appropriate apps for any url. Should the app be a url handler for such domain. Sololearn apps supports code.sololearn.com, www.sololearn.com.
When i click any of the linked Q&A or code or even post links with/without '?ref=app'. It will always promp wheather I should open in a web browser or sololearn app unless i set sololearn as default.
Even webapk's(if installed) support opening certains domain in installed webapps.(recent stackblitz site for the react tutorial is a good example)
There are also android instant apps which allow opening apps without installing the whole thing.
You don't need to do this server side. It has been happening client side as far as i can remember.

Answer 4

According to one of your 1st answers. The ios app needed '?ref=app' to open links in the app. Android app did not have an issue with/without the parameter. (The app is the issue.)
Feed posts being *app only* won't open in the app and error 404 when on the web, even though you have installed the ios app.

Answer 5

I just read your edited post Code Crasher
Both links open in the app on android. I also, like david, have been removing them for a while. It's there for tracking purpose, only. Unless, the ios app depends in a weird way on that parameter...

Answer 6

AJ #Infinity Love
Regarding the querystring:
?ref=app
This isn't related to the HTTP Referrer header in anyway.
This appears to be the same key=value pair produced on the web app as well.
I'm honestly not sure what it's purpose is. I typically remove it as it takes up characters.
Has anyone else seen "?ref=web" as well?

Answer 7

𝐊𝐢𝐢𝐛𝐨 𝐆𝐡𝐚𝐲𝐚𝐥 you should direct them in your code to not use the Google browser but when it ask to click the SoloLearn icon after they click on whatever project from the code.

Answer 8

David Carroll Yes I know that this is key value pair but this is defined to identify in back-end where we have to redirect request. This is a kind of HTTP referer as my knowledge. You can write anything according to you. You can write ?ref = abc or ?ref = xyz but in back-end we can use for any purpose who knows. So as per my knowledge Sololearn used this key value as HTTP referer.

Answer 9

𝐊𝐢𝐢𝐛𝐨 𝐆𝐡𝐚𝐲𝐚𝐥 ?ref = app. Here ref is call as referer means where you want to redirect your URL, where you want to send your request. So here ref = app means your request will go on Application by default when you open in mobile. Sometimes you can see ref = web or something else.
If you want to know more about referer you should learn about HTTP referer.

Answer 10

𝐊𝐢𝐢𝐛𝐨 𝐆𝐡𝐚𝐲𝐚𝐥 When you takes link from Sololearn Website and want to link in your code then don't forget to write this at the end of url.
?ref=app

Answer 11

David Carroll I think Lord Krishna explained whatever I wanted to say.

Answer 12

Code Crasher Different people write different according to their requirements, according to their understanding so it is not necessary to write ref = web or ref = app. We can write anything as I have previously explained. But the purpose in back-end maybe same. Here Sololearn wrote ref = app because it's look like meaningful name and understandable thing.

Answer 13

It's working fine for me too:)

Answer 14

May be