Windows 7 ((TOP)) Download Microsoft Link
The below links are directly from the official Microsoft servers. All of them are Service Pack 1 (SP1) ISO files and are roughly 5.5GB in size. So first, download the correct ISO file as per your existing Windows 7 license. Then, choose 64-bit or 32-bit based on your System type.
windows 7 download microsoft link
We have given multiple links and have mentioned multiple ways above to download Windows 7 ISO free of cost. But mind you, although the file download is free, you still need to have a valid Windows 7 key in order to proceed with the installation.