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Enables support for TLS 1.3 0-RTT, or early data. This allows some HTTP requests to be sent during the TLS handshake, decreasing latency by a round-trip. This is the TCP version of the analogous feature in QUIC.


Early data is an optimization to make pages load faster. It has been successful in QUIC, and this enables a similar optimization in TLS 1.3 over TCP. Note that, while we call it "0-RTT", it is zero roundtrips from TLS itself. Unlike QUIC, requests sent in early data must still wait for a TCP roundtrip.



Specification link

Specification being incubated in a Community Group

Status in Chromium


In development (tracking bug)

Consensus & Standardization

After a feature ships in Chrome, the values listed here are not guaranteed to be up to date.


Last updated on 2021-05-10