The best replacement for applet is application.

The best alternatives to applet are rated as following:
★★★★★  application
★★★★  servlet
★★★★  japplet
★★★  javascript
★★  jframe
★★  web start
★★  app
★  object tag
★  swing
★  javafx
★  application java
★  servlet difference
★  widget
★  java application
★  java web start
  jnlp
  activex
  midlet

Your alternative for applet is not listed? Suggest!
Speaking about applet, one probably shouldn't forget about jdbc.

Other search terms related to applet and their ratings are:
★★★★★ jdbc
★★ servlet
★★ object tag
★ jnlp
You have in mind a companion for applet and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of applet in all years. Click on graph for more.
applet
application
servlet