This is Mavo App to keep track of sales done. Is really a basic system, but it can be used as a starting point for more complex situations.
You can find a demo which stores data in the device local storage at this link.
To store data to dropbox, replace the property attribute "local" in the body tag with the sharable link of a csv o json file in your dropbox account, and add the mv-plugins="dropbox" property:
<!-- before -->
<body [...] mv-storage="local" mv-format="csv" [...]>
<!-- after -->
<body [...] mv-storage="https://www.dropbox.com/path/to/the/file/" mv-plugins="dropbox" mv-format="csv" [...]>If you want to store your entries to another remote backend (e.g. github) take a look at the offical Mavo documentation.