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Licence and Credits

Iman edited this page Sep 6, 2026 · 2 revisions

Licence and credits

Caspian wiki

This guide comes from the existing README. Its measurements retain their original dates; this documentation move does not report a new test run. English | فارسی | Русский | 中文

Licence

AGPL-3.0-or-later, with three additional terms under section 7. All three are of a kind section 7 permits and none restricts what you may do with the software: preserve the copyright notice, this attribution and a visible reference to the Caspian project in any user interface; mark your version as changed if you modify it; and do not use the authors' or the project's names for publicity, which includes soliciting donations, sponsorship or grants in those names. The full text is in LICENSE and the terms are in NOTICE.

That third term restricts the use of NAMES and nothing else. You remain free to run, study, modify and redistribute the software under the AGPL, for any purpose including a commercial one. What you may not do is raise money in the authors' name.

The AGPL rather than the GPL, because this program is normally operated as a service other people connect to, and section 13 closes the gap the plain GPL leaves. Not a permissive licence, because the binary statically links GPL-3.0-or-later code: github.com/sagernet/sing and github.com/sagernet/sing-shadowsocks, both reached through xray-core. So the combined work must be on GPL-family terms, and MIT or Apache-2.0 are not available for it.

Built on

Caspian is a small amount of code around other people's work. The engine is xray-core, and the share-link parser is XTLS's. Neither project endorses this one; they are credited because the work is theirs.

Project Licence What it does here
xray-core MPL-2.0 The proxy engine, linked in-process rather than run as a separate program
libXray MIT The share-link parser, vendored under third_party/libxray-share/
REALITY MPL-2.0 The TLS camouflage transport
uTLS BSD-3-Clause TLS fingerprint mimicry
quic-go MIT The QUIC stack Hysteria2 runs on
gVisor Apache-2.0 The userspace network stack the TUN inbound uses
sing and sing-shadowsocks GPL-3.0-or-later Shadowsocks 2022, and the reason this project is copyleft
netlink Apache-2.0 Interfaces, addresses and routes
miekg/dns BSD-3-Clause DNS message handling
gorilla/websocket BSD-2-Clause The WebSocket transport
CIRCL BSD-3-Clause Post-quantum key exchange
Wintun Wintun Prebuilt Binaries License The signed wintun.dll tunnel driver on Windows
.NET runtime and Windows Forms MIT The self-contained Windows helper and tray app runtime
System.ServiceProcess.ServiceController MIT Windows service control from CaspianControl.exe

The Windows installation has one separate third-party DLL: wintun.dll. Caspian distributes the official signed Wintun 0.14.1 binary without changes. Its license is in third_party/wintun/PREBUILT-BINARIES-LICENSE.txt and is copied to C:\Program Files\Caspian\WINTUN-LICENSE.txt during installation.

caspian-tethering.exe and CaspianControl.exe are self-contained .NET programs. Their .NET components are inside the executable files, not beside them as extra DLLs. The .NET license and notices are in third_party/dotnet/. The Windows SDK reference package is a build input and is not installed with Caspian.

It also needs hostapd, dnsmasq, nftables, iw and iproute2 on the machine. Those run as separate programs rather than being linked, so their licences do not affect this one, but the appliance is nothing without them.

NOTICE carries the full record: every module in the binary, the licence read from its own licence file, and the compatibility reasoning.

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