Ask HN:What are the best opensource web frameworks?

[anandrm]

We are planning to develop a web framework for the user configuration and management of a system Application. What are some of the open source tools we can look into for this, we need to support concurrent user configuration ,clusters . I do have ruby on rails , Dangjo as options .Any expert suggestions ?

[el_guapo]

Flask

[anandrm]

Thanks.. looks interesting.