seasocks keeps a WebSocket server small enough to link into your own binary

A web server sized for a feature, not for a site

Seasocks describes itself as a tiny embeddable C++ HTTP and WebSocket server, and the project summary calls it a simple, small, C++ embeddable webserver with WebSockets support. The word embeddable is doing the heavy lifting here. The intended deployment is not a daemon on a box serving a site, but a library linked into an application that needs an HTTP endpoint and a socket channel of its own.

The feature list is short and specific: a simple C++ API, serving static content from disk, an API for building WebSocket servers, a simple command line binary for quick serving of static files only, support for the newer Hybi-10 and Hybi-16 WebSockets as well as the older Hixie style, and support for Linux and Windows.

Six items for a server that other people write a thousand lines to achieve. That brevity is the design, and it is also the boundary. The repository topics include c-plus-plus and cpp14, so the code targets a C++14-era toolchain, which is a sensible constraint for a library you intend to vendor.

If your requirement is a WebSocket control plane for a debugger, an IDE, a build tool or an instrument, that is the shape this fits. If your requirement is a website, the following sections explain why it is the wrong answer.

Three WebSocket dialects accepted by one server

The protocol coverage is where Seasocks puts its real effort. It supports the newer Hybi-10 and Hybi-16 WebSockets as well as the older Hixie style, and the project topics list websocket-server and websockets.

Accepting three dialects matters in practice because clients do not agree. Hybi-16 is the modern framing, Hybi-10 is an earlier revision with different framing details, and Hixie is the original handshake style that some older clients still emit. A server that only understands one of them shows up as a connection that opens and then silently fails, which is annoying to debug from the browser side.

The consequence for an embedder is a slightly wider client compatibility surface at no configuration cost. The cost on the other side is that the implementation has to carry three code paths, so the surface area for parsing bugs is larger than in a server that implements one dialect only. The README does not describe the handshake code in detail, and it does not point to any protocol conformance notes, so this is an area where reading the source is the only way to know which edge cases are covered.

Because the feature list mentions a command line binary for static files only, protocol coverage is most relevant to the embedded use, where your own client code is often the only client.

The command line binary is for static files, nothing more

There is a simple command line binary for quick serving of static files only. The wording is precise, and it should be read literally. The binary is a convenience for looking at a directory of HTML or assets during development, not a general server configuration tool.

Static content comes from disk. That is the storage model: no database, no cache layer, no template engine, no file watching behaviour described anywhere in the README. The directory you point it at is served as it is.

Separating the binary from the library is a deliberate design point. The static server is what you run while building an interface, and the C++ API is what your program calls when it needs to serve that interface with real data. The README lists limited support for custom content generation, with servlets given as the example of what is not really there, so the assumption is that anything dynamic is handled by your own code through the API rather than by the server framework.

A practical implication: if you planned to deploy the binary alone in front of a real application, you will need a different tool for the static-plus-dynamic job.

What the README says Seasocks will not do

The most useful part of the README is the section titled Stuff it doesn't do, and it deserves to be quoted rather than paraphrased into marketing. According to that list, Seasocks is not nearly as configurable as Apache, Lighttpd, Nginx, Jetty, and similar servers; it provides only limited support for custom content generation such as Servlets; it has been designed for WebSocket based control; and it probably won't work on other systems, with patches to support other systems welcome but not a priority.

That is four explicit boundaries, and three of them are about fit rather than about missing features. Being less configurable than Nginx is not a defect for the target use, because the target use does not involve virtual hosts, access rules, or a configuration language. The honest reading is that Seasocks is not competing with those servers, it is sitting in a different slot.

The platform statement deserves the most attention. Linux and Windows are supported. Elsewhere, the README predicts it will probably not work, and asks for patches while making clear those patches are not a priority. If your deployment target is a BSD, a container base image you did not choose, or an embedded system, that sentence is your risk assessment.

Note also that the list of things it does not do does not include TLS termination, and the README does not mention TLS at all. Do not assume the server terminates HTTPS for you.

Getting in: the wiki tutorial and one example file are the documented path

The README does not contain an installation recipe. For getting started it says to check out the tutorial on the wiki, and it points at src/app/c/ws_test.cpp as an example. Those two references are the whole documented entry path, and there is no command sequence in the README to copy, so this article does not invent one.

What the repository layout tells you is how the project is built and packaged. There is a CMakeLists.txt at the top level, a cmake/ directory of build modules, a conanfile.py alongside a ConanCenter badge in the README, and a test_package/ directory, which is the conventional layout for a Conan package test. scripts/ holds helper scripts, .clang-format fixes the C++ style, and TODO.md records outstanding work.

The CI badge and the codecov badge in the README point to an automated build and coverage setup, and there is a .github/ directory for workflow definitions. That matters for an embedder: a library with continuous integration and coverage reporting is a safer thing to vendor than one without, and the presence of a ConanCenter package means you may not need to build it from source at all.

The two questions the README does not answer are which CMake version and which compilers are supported, and what the public header layout looks like. Both are visible in CMakeLists.txt and src/ if you need them.

Pushes in 2026, but the last tagged release is from 2023

Maintenance here needs two separate dates, because they tell different stories. The last push to the repository was on 2026-07-17, so the tree is being worked on. The release history, however, shows v1.4.6 on 2023-09-08, v1.4.5 on 2022-08-28, and v1.4.4 on 2020-08-07.

That is a meaningful gap. Work has landed in the repository since the last release, which means what you get from a tagged release and what you get from the default branch are not the same thing. For a library that you are linking into a product, deciding which of those you consume is a real decision, not a detail.

The license is BSD-2-Clause, with the LICENSE file at the repository root. That is a permissive license, and for a library meant to be embedded in other programs it is the right kind of choice, since it does not oblige you to publish anything about your own application.

One more repository artefact is worth a look before you build on this. The top level of the tree also carries .idea/ and .settings/ directories, .project and .cproject files, and a .editorconfig, which describe the development environment of the maintainers and tell you nothing about the API.

Where Seasocks loses to Nginx and Jetty, and where it wins

The README itself sets up the comparison, so there is no need to invent one. Apache, Lighttpd, Nginx and Jetty all offer far more configuration: virtual hosts, access control, load balancing behaviour, logging pipelines, and in Jetty's case a servlet model for generating content on the fly. If your requirement list includes any of that, Seasocks will feel thin, and the project says so directly.

The difference in approach is the point. Those servers are general purpose HTTP servers that happen to support or host WebSocket traffic. Seasocks is built around a WebSocket based control channel, with a small C++ API so the program that owns the logic also owns the socket. The server is not a separate deployment unit; it is a set of calls inside your process.

That difference also changes what an upgrade costs. A configuration change in Nginx is a file edit and a reload. A change in Seasocks is a rebuild and relink of the host program, and the API is small enough that a version bump is something you can read in an afternoon.

The trade is straightforward: you give up the ecosystem and the configuration surface of a mature server, and in exchange you get a dependency you can embed, a BSD license, and a project whose stated design goal matches a narrow and common need.

Editorial conclusion

Seasocks fits programs that need to open a WebSocket control channel to a browser or another tool from inside their own process, especially when embedding matters more than configuration breadth, and it is a reasonable choice for a quick static file binary during development. It is the wrong tool for a public-facing site that needs virtual hosts, TLS termination in the server, or servlet style dynamic content, and the wrong tool for any platform other than Linux or Windows. Before you build on it, check the wiki tutorial and the example in src/app/c/ws_test.cpp for the API shape you need, confirm the CMake and Conan route in CMakeLists.txt and conanfile.py matches your toolchain, and note that the most recent tagged release was v1.4.6 on 2023-09-08 even though the last push was on 2026-07-17.

Frequently asked questions

Official sources

1. Issues
2. License: BSD-2-Clause
3. mattgodbolt/seasocks on GitHub
4. README
5. Releases