Skip to content
quiczquiczquicz

Feature comparison

Updated 2026-07-28 (rows reconciled to the current README / source, 2026-08). Sources: project READMEs, source code inspection, RFC compliance tracking. Mirrors the standalone feature_comparison.md.

Feature RFC quic-go quiche s2n-quic quicz Gap
QUIC v1 transport 9000 ✅ ✅ ✅ ✅ —
QUIC v2 9369 ✅ ❌ ❌ ✅ quiche/s2n-quic V1 only
TLS 1.3 9001 ✅(Go crypto/tls) ✅(BoringSSL) ✅(s2n-tls/rustls) ✅(pure Zig) —
0-RTT (early data) 9001 ✅ ✅ ✅ ✅ —
Loss detection & recovery 9002 ✅ ✅ ✅ ✅ —
Connection migration 9000 ✅ ✅ ✅ ✅ —
Path validation 9000 ✅ ✅ ✅ ✅ —
Retry + address validation 9000 ✅ ✅ ✅ ✅ —
Stateless reset 9000 ✅ ✅ ✅ ✅ —
Key update 9001 ✅ ✅ ✅ ✅ —
Version negotiation 9368 ✅ ✅ ✅ ✅ —
DATAGRAM extension 9221 ✅ ✅ ✅(unstable) ✅ —
Multipath draft ✅ ❌ ❌ ✅ —
ECN 9000 ✅ (rx only) ✅ ✅ ✅ quiche does not send ECN
PMTU discovery 8899 ✅ ✅ ✅ ✅ —
GSO/GRO — ✅ ❌ ✅ ✅ quiche defers to app-layer I/O
Connection pool — ✅ ❌ ❌ ✅ —
Async I/O runtime (multi-conn) — ✅(goroutine) ✅(tokio) ✅(tokio) ✅(std.Io) std.http model: accept + per-conn handler
qlog draft ✅ ✅(feature-gated) ❌(event subscriber) ✅ —
Fuzz targets — ✅(OSS-Fuzz) ✅ ✅ ✅ —
NewReno 9002 ✅ ✅ ❌ ✅ s2n-quic: CUBIC+BBR only
CUBIC 9438 ✅ ✅ ✅ ✅ —
BBR — ✅ ✅ ✅ ❌ removed 2026-08 in favor of CUBIC (see README)
HyStart++ draft ❌ ❌ ✅ ✅ slow-start RTT-monitor early exit
PTO jitter 9002 ❌ ❌ ✅ ✅ avoids timeout synchronization
Fast retransmission 9002 ✅ ✅ ✅ ✅ —
App-limited (RFC 8312 §5.8) 8312 ✅ ✅ ✅ ✅ 3×MTU threshold
Packet pacing 9002 ✅ ✅ ✅ ✅ —
AES-128-GCM 9001 ✅ ✅ ✅ ✅ —
AES-256-GCM 9001 ✅ ✅ ✅ ✅ —
ChaCha20-Poly1305 9001 ✅ ✅ ✅ ✅ —
X25519 ECDH 8446 ✅ ✅ ✅ ✅ —
X25519Kyber768 (PQ) draft ✅ ✅ ✅ ✅ —
HTTP/3 9114 ✅ ✅ ❌ ✅ full connection mgmt, SETTINGS, GOAWAY, stream state machine
QPACK static table 9204 ✅ ✅ ❌ ✅ —
QPACK dynamic table 9204 ✅ ✅ ❌ ✅ dynamic table + encoder/decoder instructions + header block
HTTP Datagrams 9297 ✅ ❌ ❌ ✅ Quarter Stream ID + payload frame format
WebTransport draft ✅ ❌ ❌ ✅ full session mgmt, uni/bidi frames, CLOSE capsule, datagram
Stream reset partial delivery draft ✅ ❌ ❌ ✅ opt-in enable_reset_partial_delivery
External interop — — — — ✅ all three —
Pure-language TLS (no C) — ✅ ❌ ❌ ✅ —
FIPS 140-3 — ✅(Go 1.26+) ❌ ❌ ❌ quic-go only
XDP zero-copy I/O — ❌ ❌ ✅(unstable) ❌ s2n-quic only

Coverage summary

Section titled “Coverage summary”
Metric quic-go quiche s2n-quic quicz
Transport (19 items) 19/19 14/19 14/19 19/19
Congestion (8 items) 6/8 6/8 7/8 7/8
Cipher suites (5 items) 5/5 5/5 5/5 5/5
Application layer (6 items) 6/6 3/6 0/6 6/6
Platform (3 items) 2/3 0/3 1/3 1/3
Total (41 items) 38/41 28/41 27/41 40/41

quicz ships every transport, cipher, and application-layer feature; the open items are BBR (deliberately removed) plus the platform-only FIPS / XDP rows.

Gap analysis

Section titled “Gap analysis”

Mandatory gaps (all three have) — ALL CLOSED:

  1. AES-256-GCM — DONE (675e7ca)
  2. X25519Kyber768 — DONE (675e7ca)

Recommended (2/3 have) — ALL CLOSED:

  1. QPACK dynamic table — DONE (c8e605c)
  2. Complete HTTP/3 connection management — DONE (a15d22d)

Optional (1/3 or fewer):

  1. HTTP Datagrams (RFC 9297) — DONE (da6a670)
  2. Complete WebTransport session — DONE (a961f3e)
  3. Stream reset partial delivery — DONE (8d0ef2c)
  4. FIPS 140-3 — quic-go only
  5. XDP zero-copy I/O — s2n-quic only

Performance

Section titled “Performance”

quicz’s own measured numbers (first-party: real-handshake throughput, latency, loss recovery, CPU) live on the Performance page.

Production tuning

Section titled “Production tuning”

See Production tuning for recommended configuration values, PTO-jitter guidance, congestion-control selection, and initial-RTT tuning per deployment.