Looking a good flowchart apps for predesigns development

We are looking for an apps, free if possible, that would help us setup a flow chart design of a series of task prior any actual VB/SQL development.  We have a very complex proyect that we need to present how the flow of operatins will go so it can be authorized by our boss.   We are using Word and one thing we have seen is we have to keep changing it as we go along.  We would like something that we can click a box or a shape out of the flow and move it to another location.

Hope we gave enough info that would you guys helps us

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Thank you guys in advance!!