We have a similar Html5/AJAX powered offering[1] as well though in addition to Postgres we also support a number of other database types (MySQL, Oracle, MS SQL Server). Looking forward to trying this out to see how it compares.
To clarify, our free cloud version is a complete product. The only difference between it and the paid plans is the number of simultaneous connections and the organization, team, and audit management features.
Just click on the 'Fetch More' button, and 50 more rows will be retrieved. For cloud based _free_ solutions, I haven't found anything better than this.
[1]: http://www.jackdb.com/