Is there a way to get Feed The Beast offline?

Solution 1:

According to this reddit page, it isn't possible with the current versions Feed The Beast launcher. Instead, it was suggested that you export the modpack to the MultiMC launcher and launch it offline through that.

Exporting modpacks to MultiMC

In order to play Feed The Beast modpacks with MultiMC, you will need to download them using the offical Feed The Beast launcher first, and then move it to MultiMC. This is what you need to do accomplish this:

1. Download the Feed The Beast launcher, and download the modpack of your desire.
2. After it has downloaded (and you are at the Minecraft main-menu), exit it.

3. Download the MultiMC launcher from their homepage, extract it, and run it.

4. Click the Accounts button in the top right of the main window, and choose Account Manager. Proceed to enter your Minecraft login details.

5. Click the Add a new instance button in the top left of the main window. Proceed to name it, and choose the Minecraft version of the original modpack.
6. Navigate to the folder you installed the FTB launcher to, and enter the folder of the modpack you want to export. Copy all the files and folders to your instance folder. This can be located at <where you extracted MultiMC>/Instances/<your instance name>

7. The last thing you need to do is right-click on your modpack instance and click Edit Mods. From here click the Install forge button on the right-hand side of the window. Proceed to install the latest version of forge for your Minecraft version.

8. Now, with the instance selected in the main screen, you will be able to click the Play offline button in the right sidebar (you may need to be online the first time you try to do this).

And there we go. You can now play Feed The Beast modpacks in offline mode!

I hope this helps.