It seems that you're using an outdated browser. Some things may not work as they should (or don't work at all).
We suggest you upgrade newer and better browser like: Chrome, Firefox, Internet Explorer or Opera

Edit: GoG won't let me post any links, so I base64 encoded them. Google it if you don't know how to decode them.
I'll probably be warned for this, but as I explained to GoG support, I want to be able to contribute to the forum with quality content without having to shitpost to get my rep up :/

Bartman3010 posted a thread(1) about this before and I had the same enquire, so I contacted Young Horses (Devon) about custom levels in the GoG version of the game(2).

The most recent version of Octodad on GoG has the editor and it can load custom levels, including the ones hosted on the Steam workshop. I can't be bothered to write an entire piece on it, so here's a short how-to:
1. Have a friend with the Steam version of the game download some of the levels you want.
2. The levels will appear as self-contained zip files in the folder "$GAME_DIRECTORY/Content/Workshop".
3. Have him/her send the levels to you and then put the the levels in the same folder on your end.

There are currently no 3rd party hosters dedicated to hosting Octodad levels and GoG doesn't offer a service similar to Steam Workshop, so expect this to be your primary resource of getting custom levels.
Young Horses might release a "Best of" level pack in the future on GoG or on their own website if there is a demand for it and if they can get the permissions of the mod/level creators.

Devon also shared a collection of mods and levels created by Kevin Geisler and one collection made by the rest of the team, both of which are available here: link ...(3) link ...(4) (uploaded by me, straight from the Support Ticket attachment)

A big shout-out to Devon for being an awesome guy and a thank you to everyone involved in the creation of Octodad #2.
See you in Octodad #3 (or <insert new ip>)!

(1) aHR0cDovL3d3dy5nb2cuY29tL2ZvcnVtL29jdG9kYWRfZGFkbGllc3RfY2F0Y2gvY3VzdG9tX2xldmVsc19taXNzaW5nX2luX2dvZ2NvbV92ZX JzaW9u
Post edited March 06, 2014 by Broscar
Broscar: Edit: GoG won't let me post any links, so I base64 encoded them.
You may be over thinking this.
Thank you, Gydion.

All links, in order of appearance:!3QcnAbwD!UlAsIhVPdh-Cr3Aeflpiv-M06YdTSPU6yOq4fOSCtUE!FZVCwA4b!GCSv2FW1yFv4KeCXe6S3hnr0A_hJUt_VbUvlkyyTkQI

I don't know whether the support ticket is visible for other freshdesk accounts or not (and not everyone wants an account just to check my source), so I've attached a screenshot of the support ticket with this post.
moddb has a page for octodad

so that might be a good place for gog users to upload there own custom levels if they have made any they would like to share.