The ISO images for Windows 10 Technical Preview has gone live for free public download via Windows Insider Program as scheduled at 9am PST on October 1st, 2014. Windows 10 was announced by Microsoft in an event in San Francisco a day before.

Here’s how you can download and install Windows 10 Technical Preview:

  1. Visit https://insider.windows.com/ to sign up for the Windows Insider Program. A Microsoft account is required.

    Windows Insider Program

  2. Optionally, read the system requirements, which is pretty much similar to Windows 8/8.1.
  3. Download the Windows 10 ISO from http://windows.microsoft.com/en-us/windows/preview-download?ocid=tp_site_downloadpage (in fact, you should be able to visit this page and start the download without signing up).
  4. Burn the ISO to DVD or USB flash drive (with tool such as Rufus and Windows 7 USB/DVD Download Tool), or mount it in virtual machine if you intend to install Windows 10 in virtual environment.
  5. Double-tap or double-click setup.exe, or boot from the installation media, and then follow the steps.

In addition to Windows Insider Program for general public, Microsoft also makes available Windows 10 Technical Preview for Enterprise for evaluation purpose by IT professionals and business users. Windows 10 Technical Preview for Enterprise is available from http://www.microsoft.com/en-us/evalcenter/evaluate-windows-technical-preview-for-enterprise. If you’re MSDN subscriber, Windows 10 TP, Windows 10 TP for Enterprise, Windows 10 Server TP, Windows 10 Server Datacenter TP and Windows 10 Hyper-V Server TP are also available for download.

Currently, only Windows 10 in English (United States), English (Great Britain), Chinese (Simplified), Portuguese (Brazil) are available.

Also note that Windows Update will be set to automatically install important updates as they become available. You won’t be able to turn off automatic updates in Windows Technical Preview.

For those who want to directly download the Windows 10 Preview ISO, here’s the direct download links, together with the SHA-1 checksum for the files. Note that the download size is in decimal (1000), and not binary (1024).

Most importantly, the product key you need to install and activate Windows 10: NKJFK-GPHP7-G8C3J-P6JXR-HQRJR (note: the product key is served just as backup purpose, it’s not required for install and Windows 10 is auto-activated upon installed)

Windows 10 Professional

English 64-bit (x64): WindowsTechnicalPreview-x64-EN-US.iso (4.10 GB) EB75A3D3C0F621F175B75DC65DB036D0E00EAC43
English 32-bit (x86): WindowsTechnicalPreview-x86-EN-US.iso (3.16 GB) 73AC23AD89489855F33CA224F196327740057E2E
English (United Kingdom) 64-bit (x64): WindowsTechnicalPreview-x64-EN-GB.iso (4.08 GB) 17C6CD7224D13DB61B93A4A9D38202E3A0019378
English (United Kingdom) 32-bit (x86): WindowsTechnicalPreview-x86-EN-GB.iso (3.17 GB) BFF496678A09255738BFBFA14903295D55478C33
Chinese (Simplified) 64-bit (x64): WindowsTechnicalPreview-x64-ZH-CN.iso (4.26 GB) 135E3193571C5AF9FBF36D24D07B2BE7EE49B2E8
Chinese (Simplified) 32-bit (x86): WindowsTechnicalPreview-x86-ZH-CN.iso (3.28 GB) 3EE3A2033BE666BA55AFED3FCF6BB52A7C15C7CC
Portuguese (Brazil) 64-bit (x64): WindowsTechnicalPreview-x64-PT-BR.iso (4.05 GB) 3DA91BB9EA7316F670C0A132D940FC1D58BAB296
Portuguese (Brazil) 32-bit (x86): WindowsTechnicalPreview-x86-PT-BR.iso (3.13 GB) 611FE8F94906EFE75F64D197913344AC040DF644

Windows 10 Enterprise

English 64-bit (x64): 9841.0.140912-1613.FBL_RELEASE_CLIENTENTERPRISE_VOL_X64FRE_EN-US.ISO
English 32-bit (xx86): 9841.0.140912-1613.FBL_RELEASE_CLIENTENTERPRISE_VOL_X86FRE_EN-US.ISO

The installed Windows 10 Preview has the build version of 6.4.9841.0.140912-1613, but should be updated pretty soon. The Technical Preview version of Windows 10 expires on April 15, 2015, giving you about half a year free usage.