The Steam version of Five Nights at Freddy's does not have any obtainable achievements.
However, these achievements are official and are included in the console ports of the game.
That being said, feel completely free to try and get all of these achievements just for funsies!
This guide also contains some SPOILERS for the game, you have been warned!

“Survived the 1st night.”
Beat Night 1.

“Survived the 2nd night.”
Beat Night 2.

“Survived the 3rd night.”
Beat Night 3.

“Survived the 4th night.”
Beat Night 4.

“Survived the 5th night.”
Beat Night 5.

“Survived the 6th night.”
Beat Night 6.

“Completed the custom night on hardest difficulty.”
Beat Custom Night on 20/20/20/20 difficulty.

“Kept Foxy from escaping during night 4.”
Beat Night 4 checking Foxy as much as you can to prevent him from leaving Pirate Cove.

“Kept Freddy from getting to cams 4A or 4B during night 5.”
Beat Night 5 checking Freddy as much as you can to prevent him from reaching East Hall.

“Experienced a jumpscare, and then... who knows?”
Get jumpscared.