There are currently total 35 contributors on steemit github .
Lets have a look at some top of them.
Michael Vandeberg
He is the main programmer on the this project.
He has 1,225 contributions in the last year.
He is a C++ programmer. He has 734 commits and added 45,622 lines of code.revflash
He is the second most important coder on this project.
He has 273 commits and added 119,123 lines of code.theoreticalbts
He has 257 commits and added 13,755 lines of code.
He has also contributed in various other repositories like steemwatch, bitshares etc.Justin Welch
He has 75 commits and added 1,293 lines of code.
He has also created a awsome steempostexample repository.
There are many other contributors.
You can check out here:
https://github.com/steemit/steem/graphs/contributors