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Protect your webhook endpoint with two controls: IP allowlisting and signature verification. Use both together.

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Source IP addresses

CPN sends webhook notifications from a fixed set of IP addresses. Add these to your firewall or cloud security group allowlist. The same addresses apply to testnet and mainnet:
  • 35.169.154.32
  • 3.90.127.28
  • 3.230.111.7
  • 54.88.227.75

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Signature verification

Each webhook request includes a signature you can use to confirm it came from Circle. See Verify webhook signatures for the algorithm and code examples.