Sublime Gofmt

This Sublime Text 3 package adds support for running gofmt on your Go source files. It runs on save by default, but that can be disabled. You can run it manually via a palette command (Gofmt: Format this file).

If gofmt encounters errors, the plugin will mark the lines and highlight those errors in your source file.

Goimports

If you want to use goimports instead, open to Sublime Text -> Preferences -> Package Settings -> Gofmt -> Settings - User and enter a config like this:

{
  "cmds": [
    ["goimports", "-e"]
  ]
}

Note that cmds is an array, so you can put multiple commands in there, if you want to run the file through more than one formatter for some reason.