The easiest way to download and host a dedicated server is through Steam.
You can find a how to on the official wiki page.
You can also download the server files directly here:
Windows64 – v0.21.29 build 11012271
Windows32 – v.0.21.29 build 11012271
Linux64 – v0.21.29 build 11012271
MacOS – v0.21.29 build 11012271
Older versions:
Windows64 – v0.21.28 build 10560541
Windows32 – v.0.21.28 build 10560541
Linux64 – v0.21.28 build 10560541
MacOS – v0.21.28 build 10560541
Windows64 – v0.21.27 build 10229868
Windows32 – v.0.21.27 build 10229868
Linux64 – v0.21.27 build 10229868
MacOS – v0.21.27 build 10229868
Windows64 – v0.21.26 build 9973476
Windows32 – v.0.21.26 build 9973476
Linux64 – v0.21.26 build 9973476
MacOS – v0.21.26 build 9973476
Windows64 – v0.21.25 build 9650339
Windows32 – v.0.21.25 build 9650339
Linux64 – v0.21.25 build 9650339
MacOS – v0.21.25 build 9650339
Windows64 – v0.21.24 build 9363221
Windows32 – v.0.21.24 build 9363221
Linux64 – v0.21.24 build 9363221
MacOS – v0.21.24 build 9363221
Windows64 – v0.21.23 build 9096788
Windows32 – v.0.21.23 build 9096788