Is there any alternative to MS Visio?

Yes, there are many alternatives to MS Visio which are open source. I am listing a few of them below.

1. Lucid Chart
   
2. Smart draw
   
3. ASCIIFlow Infinity
   
4. Gliffy
   
5. yEd Graph Editor
   
6. Graphviz
   
7. LibreOffice Draw
   
8. Dia
   
9. Draw.io
   
10. Pencil Project