What is an alternative to PowerDesigner or IBM Rational Rose?

I need a powerful development manager like Sybase Power Designer or IBM Rational Rose that support sequence diagrams, data flow diagrams and so on.

Can somebody suggest a good alternative?

Dia

Dia is a diagram editor that can be used to draw flow charts, UML diagrams etc.

you can try one of these:

• Visual Paradim
• EMF - Eclipse Modeling Framework is a good starting point and here is a tutotial for it.
• Visual Paradigm: SDE for NetBeans
• ArgoUML
• Umbrello
• Dia

Also take a look at OpenModelsphere. It is more oriented towards data modeling and can be used for both forward and reverse engineering of physical databases plus it supports a (almost) full range of UML, data modeling and business process modeling diagrams.

Oh, and its GPL v3, so no "community" versions or "non-commercial" or other "Thou shall not ..." restrictions :-)