Api Tips

Hey guys I was recently involved in a laravel project which is also connected to mobile applications through web services.. anyway I was in contact with the mobile developer and he asked me if there is a way that prevents him for making multiple api calls..

Basically he wants a real time tool that alerts him that something was changed in the database so at that time he will make a call otherwise he keeps retrieving from local storage..

I don't know if you have any idea about a free service that generates that..

Thank you in advance !