I've been looking a collection like this, but for startups/sites/internet companies.

Something that would have Facebook's[0] and Snapchat's[1] source code.

Or even something that would have Staffjoy's[2](a startup that shut down then open sourced their source code).

[0] -> https://gist.github.com/nikcub/3833406

[1] -> https://github.com/JonnyBanana/Snapchat-Source-Code-Leak

[2] -> https://github.com/Staffjoy/v2