The first tool I use in Google Search Console (the URL of which is google.com/webmasters/tools). The other is Google Analytics.
See a large image of any of the images, click in the image.
Within Google Search Console
Under Search Analytics, you’ll see how many clicks through your site has received in the last 30 days. Monitor to see that this number is growing over time.
When you click the Search Analytics label, you’re taken to a more detailed screen which shows how many search terms your website matches for. Monitor to see that this number is growing over time.
From here, within this tool, you can easily determine the average search position for each keyword phrase your site matches for and the specific URLs on your site associated with each search terms.
Within Google Analytics
Via the report Acquisition -> All Traffic -> Channels, you can easily identify all traffic from organic search. When you drill down into Organic Search you can see a graph over time of your levels of traffic from organic search.
Of course, the objective of any commercial site is not just traffic, but for your website visitors to take some action that starts them on your sales funnel. However, that is for another post.
In terms of monitoring the growth of organic search traffic, these two tools and these few important metrics and reports can help you monitor the progress of your SEO efforts.SEO Needs Link Building