Purge and recreate cache of a specific URL in Nginx proxy cache

Question

I have some websites using Nginx fcgi_cache to serve guests faster. but some day I update a menu in header or update a page.

Note: I have tried proxy_cache_purge directive and It's part of nginx commercial subscription.

Now I'm looking for a solution to purge specific URL or purge all cache at once.

Please provide me a free solution if there is one!