Cannot access or use Zapier with other apps

Written by Owner

Updated at August 20th, 2025

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Table of Contents

Cause How to fix it Challenges of IP allowlisting with Zapier Convert CIDR notations to IPs ranges Alternative to IP allowlisting

You’re trying to connect or access Zapier, but you receive an error message that is similar to one of these:

403 error: The request could not be satisfied.
Connection timeout
Access forbidden

Cause

This can happen when inbound traffic from Zapier is being blocked from reaching your application.

Zapier does not operate with a single, static range of IP addresses. Instead, Zapier uses Amazon (AWS)'s us-east-1 region, where it dynamically provisions instances as needed. This dynamic IP allocation can lead to inbound connection issues if your system is configured to only accept traffic from a fixed set of IP addresses.

How to fix it

Challenges of IP allowlisting with Zapier

Due to the dynamic nature of Zapier’s infrastructure with the AWS us-east-1 region, allowlisting the entire range of potential IP addresses is often impractical and may expose your systems to a wider range of connections than necessary.

Convert CIDR notations to IPs ranges

If your firewall or filter does not support CIDR notations, you can convert it into a range of IPs using a CIDR calculator:

Go to IPAddressGuide’s CIDR calculator.
In the CIDR to IP Range section, enter the IP block.
Click Calculate.
The results will give you the First IP and Last IP. The number of IPs in the range will be in the Total Host field.

Note

In most scenarios, allowing all IP addresses within the us-east-1 region is not a recommended security practice. This opens your instance to a significant portion of the public internet.

Alternative to IP allowlisting

All HTTP requests sent by Zapier includes the following unique header:

User-Agent: Zapier

If you unable to allowlist a broad range of IP addresses, a more secure and manageable alternative is to configure your systems to allow requests that contain the header User-Agent: Zapier.