•Shared dictionaries enable delta compression by allowing browsers to send previously cached versions as a compression reference, reducing redundant byte transfers.
•RFC 9842 improves upon the failed SDCH standard (2008-2017) by enforcing same-origin dictionary usage to prevent compression side-channel attacks like CRIME and BREACH.
•Delta compression transforms incremental changes: a 500KB bundle with a one-line fix becomes kilobytes on the wire by compressing only against what changed.
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Cloudflare is rolling out shared dictionary support in three phases starting with Phase 1 passthrough support, with an open beta planned for April 30, 2026.
This summary was automatically generated by AI based on the original article and may not be fully accurate.
Cloudflare
Netflix
Databricks