If you ever wondered how many public IP addresses Microsoft owns for its web and cloud services, here is an official Microsoft Excel spreadsheet you can download to find out.
Download link: https://www.microsoft.com/en-us/download/details.aspx?id=53602
The document contains public IP address blocks used by Microsoft for both IPv4 and IPv6. You can download the file to check out or simply scan through the list below.
IPv4 used by Microsoft
13.64.0.0/11
13.104.0.0/14
13.96.0.0/13
23.96.0.0/13
40.64.0.0/10
42.159.0.0/16
51.140.0.0/14
51.4.0.0/15
51.51.0.0/16
51.8.0.0/16
52.112.0.0/14
52.145.0.0/16
52.146.0.0/15
52.148.0.0/14
52.152.0.0/13
52.160.0.0/11
52.224.0.0/11
64.4.0.0/18
65.52.0.0/14
66.119.144.0/20
70.37.0.0/17
70.37.128.0/18
91.190.216.0/21
94.245.64.0/18
103.255.140.0/22
103.36.96.0/22
103.9.8.0/22
104.146.0.0/15
104.208.0.0/13
104.40.0.0/13
111.221.16.0/20
111.221.64.0/18
131.253.1.0/24
131.253.12.0/22
131.253.128.0/17
131.253.16.0/23
131.253.18.0/24
131.253.21.0/24
131.253.22.0/23
131.253.24.0/21
131.253.3.0/24
131.253.32.0/20
131.253.5.0/24
131.253.6.0/24
131.253.61.0/24
131.253.62.0/23
131.253.64.0/18
131.253.8.0/24
132.245.0.0/16
134.170.0.0/16
134.177.0.0/16
137.116.0.0/15
137.135.0.0/16
138.196.0.0/16
138.91.0.0/16
139.217.0.0/16
139.219.0.0/16
146.147.0.0/16
150.171.0.0/16
157.54.0.0/15
157.56.0.0/14
157.60.0.0/16
167.220.0.0/16
168.61.0.0/16
168.62.0.0/15
191.232.0.0/13
192.32.0.0/16
192.48.225.0/24
192.84.159.0/24
192.84.160.0/23
192.197.157.0/24
193.149.64.0/19
193.221.113.0/24
194.110.197.0/24
198.49.8.0/24
198.105.232.0/22
198.200.130.0/24
198.206.164.0/24
199.103.122.0/24
199.103.90.0/23
199.242.32.0/20
199.242.48.0/21
199.60.28.0/24
199.74.210.0/24
202.89.224.0/20
204.13.120.0/21
204.14.180.0/22
204.152.140.0/23
204.152.18.0/23
204.231.192.0/24
204.231.194.0/23
204.231.196.0/22
204.231.200.0/21
204.231.208.0/20
204.231.236.0/24
204.79.135.0/24
204.79.179.0/24
204.79.180.0/23
204.79.188.0/24
204.79.195.0/24
204.79.196.0/23
204.79.252.0/24
205.174.224.0/20
206.191.224.0/19
207.46.0.0/16
207.68.128.0/18
208.68.136.0/21
208.76.44.0/22
208.84.0.0/21
209.240.192.0/19
213.199.128.0/18
216.32.180.0/22
IPv6 used by Microsoft
2001:489a:2000::/35
2001:67c:1020::/48
2001:df0:7::/48
2001:df0:d7::/48
2001:df0:d8::/48
2001:df0:d9::/48
2603:1000::/24
2620:0:30::/45
2620:10c:5000::/44
2620:1ec::/36
2801:80:1d0::/48