Updated 3/6/18Stardew Valley still doesn't have official Steam Workshop support, but its modding community has come leaps and bounds since the game launched in 2016.
There's a variety of mods out there that do everything from changing what your animals look like to making fishing easier to adding items and adjusting game balance.
Most of these mods were found either on the official Stardew Valley Mod forum or at the game's Nexus Mods page, both of which are getting more amazing mods everyday An important thing to note before jumping in is that Stardew Valley developer Eric "Concerned Ape" Barone is still actively updating the game.
Since there isn't any official mod support (yet) there's a chance that mods will break or need to be reinstalled after updates, and it's advisable to back-up any files you are going to modify before doing so in case you need to revert the changes.
I'd also recommend you back-up your save data, which can be found by default at Most of these mods are simple modifications to the game's XNB files.
That means all you need to do to install them is download the modified XNB, find the corresponding XNB file in the Stardew Valley 'Content' folder—default location is "C:\Steam\steamapps\common\Stardew Valley\Content", and the XNB you are looking for may be in a subfolder within the 'Content' folder—and then replace the original XNB with the one you downloaded.
It's a slightly bigger hassle to install these mods than the XNB ones—as you first need to install SMAPI and then download DLL mods to place into SMAPI's mod folder—but it also allows those mods to make much deeper changes to the game.You can download SMAPI on the Stardew Valley modding forum, and I'll be sure to mark which mods require it to be used.Stardew Valley Mod Manager (SDVMM)There's also a great community-made Mod Manager tool created by modder yuuki called SDVMM.This will help you install and update SMAPI, as well as keep track of all of your mods.It allows you to easily activate and deactivate specific mods without having to remove the files completely, giving you more flexibility if you want to try something on this list out but potentially not keep the mod forever. The Steam Console Client or Steam CMD is a command-line version of the Steam client.Its primary use is to install and update various dedicated servers available on Steam using a command-line interface.It works with games that use the Steam Pipe content system. Create a user account named steam to run Steam CMD safely, isolating it from the rest of the operating system.All games have been migrated from the deprecated HLDSUpdate Tool to Steam CMD. Download Steam CMD for Windows: https://steamcdn-a.akamaihd.net/client/installer/3. Do not run steamcmd while operating as the root user - to do so is a security risk. As the root user, create the steam user: Next enter your password. (Note: use forward slashes for Linux/OS X and backslashes for Windows.) It is recommended you use this command only on initial installation and if there are server issues.If Steam Guard is activated on the user account, check your e-mail for a Steam Guard access code and enter it. A list of known servers that use Steam CMD to install is available on the Dedicated Servers List page. condenser is a bootstrapper for installing, configuring, & launching Steam dedicated server apps.This is only required the first time you log in (as well as when you delete the files where Steam CMD stores the login information). Note that any extra commands listed need to be executed before the app_update line. Install and automatically update any game server Git Hub Repo: https://github.com/C0nw0nk/Steam CMD-Auto Update-Any-Gameserver This tool allows the user to use Steam CMD on Windows without command lines and/or batch files.