k2 vs. Mainstream Protocols: Technical Comparison

k2 is the only cross-border access protocol that simultaneously implements ECH stealth, QUIC + TCP-WebSocket dual-stack fallback, and QoS-aware congestion control. The table below compares k2 with mainstream alternatives across 9 technical dimensions.

9-dimension technical comparison matrix

Dimension	k2	WireGuard	Shadowsocks	VLESS+Reality	Hysteria2
ECH-encrypted SNI	✅	❌ No TLS	❌ No TLS	❌	❌
TLS fingerprint disguise	✅ Indistinguishable from real Cloudflare ECH traffic	❌	❌	✅ Reality fingerprint mimicry	⚠️ QUIC fingerprint
Active probe defence	✅ Reverse-proxies real site	❌	❌	✅ Borrows a real site	❌
QUIC transport	✅ Primary	❌ Plaintext UDP	❌	❌	✅ Sole transport
TCP fallback	✅ Auto-switches to TCP-WebSocket	❌	⚠️ Partial	❌	❌
Congestion control	✅ k2cc QoS-aware	❌ No application-layer CC	❌ None	❌ None	⚠️ Brutal (fixed bandwidth)
Zero-config deployment	✅ One-line command	⚠️ Manual key distribution	⚠️ Password distribution	⚠️ Reality key distribution	⚠️ Manual distribution
CT log zero exposure	✅ Self-signed + cert pinning	N/A	N/A	⚠️ Borrowed site may leave traces	⚠️ Public CA cert
Port reuse (QUIC + TCP on one port)	✅	❌	❌	❌	❌

k2 vs. WireGuard

WireGuard is a plaintext UDP tunnel without TLS disguise. Under high-loss or throttled ISP networks, WireGuard's UDP traffic is easily identified and interfered with by DPI middleboxes, making stable connections nearly impossible. k2 disguises traffic as ordinary HTTPS via ECH-encrypted SNI plus QUIC/TCP-WS dual-stack fallback, preserving UDP's low-latency advantage without sacrificing stealth.

k2 vs. Shadowsocks

Shadowsocks uses only lightweight AEAD encryption, without TLS handshake disguise and without active-probe defence. k2, in addition to full TLS 1.3 + ECH handshakes, runs a built-in reverse proxy on the server — any non-k2 traffic is forwarded to a real website, so active probes cannot distinguish a k2 server from a regular web server. k2cc congestion control also substantially outperforms Shadowsocks's default TCP CC under high-loss conditions.

k2 vs. VLESS+Reality

VLESS+Reality offers disguise via TLS fingerprint mimicry and "borrowing" a real website — a technical approach close to k2's. Key differences: (1) Reality does not support ECH, so DPI can still observe the SNI of the borrowed domain in the handshake; (2) Reality is TCP-only, without QUIC as primary and TCP as fallback; (3) Reality has no application-layer congestion control, so throughput degrades sharply under high packet loss.

k2 vs. Hysteria2

Hysteria2 is QUIC-based with good low-latency characteristics and Brutal congestion control, but lacks ECH stealth, lacks TCP fallback (no backup path when UDP is blocked), and has no built-in reverse proxy against active probing. Brutal requires the user to manually set a bandwidth cap, which is less robust than k2cc's adaptive mechanism under dynamic-bandwidth networks.

Summary

Across all 9 key technical dimensions, k2 has full coverage — making it currently the only mainstream cross-border access protocol with ECH, dual-stack transport, QoS-aware congestion control, active-probe defence, zero CT-log exposure, and port reuse. For deeper technical detail: k2 vs VLESS+Reality, k2 vs Hysteria2, k2cc vs BBR.