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7/14/2026
Implementing a JA4H-Equivalent Fingerprint with Amazon CloudFront Functions to Mitigate Bot Traffic

Implementing a JA4H-Equivalent Fingerprint with Amazon CloudFront Functions to Mitigate Bot Traffic

Short summary

The author implements a JA4H-equivalent HTTP fingerprint using Amazon CloudFront Functions, since CloudFront only exposes TLS-based JA4 natively. The article covers how JA4+ fingerprints work, how to leverage the CloudFront-Viewer-Header-Order header, and how to compute the four-part JA4H string entirely at the edge. Code examples and design gotchas are included for practical implementation.

  • •CloudFront exposes TLS-based JA4 but not HTTP-based JA4H fingerprints
  • •Author implements JA4H-equivalent fingerprinting using CloudFront Functions and viewer header order
  • •Includes code for blocklist-based bot mitigation using CloudFront KeyValueStore

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