Offline capable web apps. https://www.amazon.com/-/de/dp/1491961651/ref=sr_1_fkmr3_2?__mk_de_DE=%C3%85M%C3%85%C5%BD%C3%95%C3%91&dchild=1&keywords=HTML5+progressive+web+app&qid=1609281538&s=books&sr=1-2-fkmr3