You kind of dropped a bit but not in a way which affects you very much (apparently, according to Ahrefs)
https://d.pr/i/HBzKpj.png (screenshot of estimated SEO keywords and traffic according to Ahrefs)
You did lose a lot of keywords, but many seem to have since recovered and it didn't seem it actually impact your SEO traffic estimates much at all
SEMRush has a neat (relatively) new tool which looks at more accurate traffic estimates across the board (not just limited to SEO):
https://d.pr/i/x41GvK.png
Again it does show a bit of a dent around April 2018. If I was going to use SEMRush data to look at this, I'd use the traffic analytics tool not the 'normal' SEO estimate charts from SEMRush (which IMO aren't very good, hence using the Ahrefs one in place of that)
This is what your site looked like in Feb 2018 before the keyword drops:
https://web.archive.org/web/20180224042824/https://www.vtiger.com/
This is what your site looked like later in June 2018:
https://web.archive.org/web/20180606021616/https://www.vtiger.com/
Completely different!
This is what your site looks like now: https://www.vtiger.com/
Again radically different. Maybe you just have a bad case of 'disruptive behavior' where Google is unwilling to rank you well, because the site keeps radically changing in terms of design and content. Sometimes doing too many changes too fast can really put Google off! 3 different designs inside of 1 year is pretty crazy
After each change, your home-page's Page Title was completely different:
Feb 2018 version: Customer Relationship Management | CRM Software - Vtiger
June 2018 version: Vtiger CRM | Customer Relationship Management Software
Current version: CRM | Customer Relationship Management System - Vtiger CRM
In my opinion everything that was done around June 2018 was a huge mistake that you are suffering for now and recovering from gradually. The June 2018 design was horrible, way worse than the Feb 2018 or current one (both were better). If a designer doesn't do a good job, don't just 'go ahead' with a terrible site design just because you paid for it
In addition to that in June 2018 your page title didn't 'begin' with the term (or a synonym of the term) "CRM". In Feb 2018 and on the current version, you either opened with "CRM" or a synonym of "CRM" which is better for SEO. The June 2018 version of the site was really bad and also less well optimised as well (that seems really obvious to me)
Part of me actually feels that the Feb 2018 version of the site was best for SEO. It did a better job of making your USPs (value propositions) stand out to the user and search engines. It blended nice, app-styled UX with functionality that was more than just 'button links'
The current version isn't bad, it certainly looks nicer visually - but the June 2018 version was a bit of a house of horrors. It makes sense it would have been active within the boundaries of the times you got dented because, it's just a bit shocking to be honest. In the Feb 2018 version of your site, more of the individual product links were listed in the top-line nav. Now they are still there but 'hidden' in drop-downs, that could be affecting things too
If I look at the technical SEO of the Feb 2018 site I can see it was relatively streamlined in terms of resource deployment:
https://d.pr/i/957ZjP.png
... but by June 2018, there were way too many resources for one homepage to be pulling in. Not only did it look plainer and uglier than before (and less helpful, with worse SEO) it was probably also laggier to boot:
https://d.pr/i/hGjfCW.png
Ugh! 89 HTTP requests!? Get outta' here
Now things seem a lot better on that front:
https://d.pr/i/7olDcI.png
So I think this is more evidence that the short-lived June 2018 site was pretty sucky and you guys bailed on it at light-speed (rightly so it was terrible!)
The question: did you see ranking drops for "CRM" related keywords in the period surrounding April 2018? Say for example, in April, May, June and July of 2018?
I'd say that you did, according to an (extremely rough) ranking movements export from Ahrefs:
https://d.pr/i/CuGsRT.png
Actual data export (formatted) here: https://d.pr/f/pwnrIF.xlsx
So which CRM related URL, was responsible for the most CRM related ranking losses which Ahrefs happened to pick up on?
https://d.pr/i/rCQ8LF.png (table image)
https://d.pr/i/7SJPbt.png (ugly bar chart)
Clearly the URL most responsible for all the drops was this one:
https://www.vtiger.com/open-source-crm/
... so how has this URL changed?
Infuriatingly, the Wayback Machine has barely any records of this URL, so closest I can get to ... just before the end of April 2018, is actually December 2017:
https://web.archive.org/web/20171226021957/https://www.vtiger.com/open-source-crm/
... it looks basically the same as it looks now. No major changes. But wait! On the old version of your homepage, the footer links to the open source CRM were bigger and more prominent than they are now. Another thing, those footer links used to be marked up with itemprop=url, now they are not (could that be making a difference? All I can say is that the coding is different)
Another question would be, between April and July 2018 - did you lose any CRM related links that were worth a lot?
Actually, apparently you did lose a few. Check some of these out:
https://d.pr/i/Zg5XER.png (MEGA screenshot, but first page of results only)
https://d.pr/f/NetqVM.png (full export, lost links which may be about 'CRM', April through July 2018 - raw and unformatted export, open the CSV file in Excel!)
Losing a CRM related link from Capterra, online peer review software experts? Yeah that could hit you hard. Most of the Mashable ones are still there, they are just redirected - but the Capterra one:
https://blog.capterra.com/free-and-open-source-crm/
... that could sting. You used to have a link with anchor text like this:
"for a price starting at about $700" - but now it's gone!
You might be thinking, aha Effect - you silly sausage! Clearly it was a comment link that got pushed down or removed by admins / mods, not a 'real' link Google would have been counted. But no I say, and I have proof to back up that denial:
https://web.archive.org/web/20170930101939/http://blog.capterra.com/free-and-open-source-crm/
That is the same post in April 2018, if you Ctrl+F for "for a price starting at about $700" - you will FIND the in-content link, which actually did matter, which Capterra have removed from their content
I am sure that in the link data you will find other such examples of lost quality links. Some will be duds and false-positives (like the Mashable ones) but some will be legit removals
By the way, although the Mashable links to you are still live, Mashable have 302 redirected the old URLs for the blog posts instead of 301 redirecting them. This means those posts, if they were valued and accrued a lot of backlinks - have been cut off from their own backlinks (as 302s pass no SEO juice). As such links contained inside of them are largely nullified (d'oh! Thanks Mashable)
What this illustrates is that, your site changed too much, the way links are formed changed, the design went through a really bad patch and also you've lost some high quality backlinks. An SEO legacy doesn't last forever, links get removed over time
In the end, these convergence of issues are almost assuredly leading your site through a tough spot. That's what I'd imagine, from a very very top-line look into this issue