If you're looking for the official Android SDK Tools (including platform-tools, build-tools, and the SDK manager), here are the direct and most reliable links.
Google distributes the SDK in several modular packages. The most critical "informative" links for direct tool access are: Update the IDE and SDK tools | Android Studio android sdk tools link
This package contains critical interface tools. Android SDK Tools: Official Download & Setup Links
Command line tools only (latest):
https://developer.android.com/studio#command-line-tools-only and the SDK manager)
After installing Android Studio, you need to configure the Android SDK:
If you only need the command-line utilities to unlock a bootloader or pull logs from your phone, you want the Platform-Tools
