Zapier does not have one static range of IP addresses. Instead, Zapier uses Amazon (AWS)'s US-EAST-1 region, spinning up instances as needed. This means there could be millions of IPs to allowlist, which often becomes impractical.
You can find Amazon's list of current ranges (subject to change) here. We might be connecting from any of the us-east-1 ranges listed on this page: https://ip-ranges.amazonaws.com/ip-ranges.json.
1. Translate IPs into ranges
An IP like
10.0.0.0/12 is listed in "CIDR" notation, which is shorthand for a block of IPs. If your firewall or filter does not support CIDR notation, you can convert this into an actual range of IPs by using an online CIDR calculator.
To calculate the range, enter your IP block in the CIDR field.
The resulting calculation will give you a Start IP and an End IP.
In most cases, allowing all of us-east-1 is not going to be the right solution. You'll need to open your instance to the wider internet.