Comment by AshishGupta93

Here are few tools I found -

Gliffy - gliffy.com

Draw.io - draw.io

Creately - creately.com

RealtimeBoard - realtimeboard.com

LucidChart - lucidchart.com

Bubbl - bubbl.us

Textografo - textografo.com

Smartdraw - smartdraw.com

Edrawsoft - edrawsoft.com

Microsoft Visio

I've not used all of them. Looking for suggestions (preferably free tool).