These plugins can help you with tasks like syntax highlighting, autocompletion, error checking, and formatting.
Visual Studio Code (VSCode):
Plugin: Terraform (by Mikael Olenfalk)
Link: https://marketplace.visualstudio.com/items?itemName=mauve.terraform
Plugin: HashiCorp Terraform (by HashiCorp)
Link: https://marketplace.visualstudio.com/items?itemName=HashiCorp.terraform
JetBrains IntelliJ IDEA / PyCharm / WebStorm / PhpStorm / RubyMine:
Plugin: HashiCorp Terraform / HCL language support (by JetBrains)
Link: https://plugins.jetbrains.com/plugin/7808-hashicorp-terraform--hcl-language-support
Sublime Text:
Plugin: Terraform Syntax (by Aleksandr Dorokhov)
Link: https://packagecontrol.io/packages/Terraform%20Syntax
Plugin: SublimeLinter-contrib-terraform-check (by Jon Berg)
Link: https://packagecontrol.io/packages/SublimeLinter-contrib-terraform-check
Atom:
Plugin: language-terraform (by Mikael Olenfalk)
Link: https://atom.io/packages/language-terraform
Plugin: atom-terraform (by David Heward)
Link: https://atom.io/packages/atom-terraform