{"id":"simple-interest","engine":"core","category":"math","name":"Simple interest calculator","fields":[{"key":"principal","label":"Principal","type":"number","default":10000,"required":true},{"key":"rate","label":"Annual rate (%)","type":"number","default":4,"required":true},{"key":"years","label":"Years","type":"number","default":3,"required":true}],"sample":{"principal":10000,"rate":4,"years":3}}