I'm not able to find the grails perspective in my latest release download of spring tool suite 3.8.2
I've created GRAILS_HOME varialble as C:\grails-2.4.4 path variable as %GRAILS_HOME%\bin
and similarly JAVA_HOME and its path variable.
Still not able to find the Grails perspective in STS.
The Grails support is no longer available for the Spring Tool Suite, at least not the Grails support that we worked on in the past. There was an announcement from Pivotal about the general topic a while ago: https://blog.pivotal.io/pivotal/news/groovy-2-4-and-grails-3-0-to-be-last-major-releases-under-pivotal-sponsorship. This also included to not working on the tooling for Eclipse anymore.
If you want to, you can download the final version of the Groovy-Grails-Tool-Suite from here: https://spring.io/tools/ggts/all. It is version 3.6.4, based on Eclipse 4.4.2.
The marketplace entry that is mentioned in another comment refers to this version of the Groovy-Grails support - and should not be installed on Eclipse versions higher than 4.4.2.
We also do not officially support and work on the Groovy support for Eclipse anymore, but there is still a version available that works with the latest versions of Eclipse.
If you are (or someone else is) interested in taking over those tooling projects, feel free to reach out to us. We would be more than happy to provide some support in taking over those projects.