Airbnb: http://nerds.airbnb.com
Balanced: http://blog.balancedpayments.com
Dropbox: https://tech.dropbox.com
CodeRanger: https://coderanger.net
Cloudera: http://blog.cloudera.com/blog/
Etsy: https://codeascraft.com
Fabio Rehm: http://fabiorehm.com
Facebook: https://www.facebook.com/Engineering
Flickr: http://code.flickr.net
Foursquare: http://engineering.foursquare.com
Github: https://github.com/blog/category/engineering
GoCardless https://gocardless.com/blog
Groupon: https://engineering.groupon.com
Harvest: https://www.getharvest.com/blog
Heroku: http://engineering.heroku.com
Honeybadget: http://blog.honeybadger.io/
Instagram: http://instagram-engineering.tumblr.com
Linkedin: http://engineering.linkedin.com
Mikamai: http://dev.mikamai.com
NextDoor: https://engblog.nextdoor.com/
Oyster: http://tech.oyster.com
Pinterest: http://engineering.pinterest.com
Quora: http://engineering.quora.com
Reddit: http://www.redditblog.com
ResolveDigital http://blog.resolvedigital.com
Simple: https://www.simple.com/engineering
Skroutz http://engineering.skroutz.gr/
SoundCloud: https://developers.soundcloud.com/blog/
SoungKick: http://devblog.songkick.com
SmugMug http://don.blogs.smugmug.com
Spotify: https://labs.spotify.com
Squareup: http://corner.squareup.com
Tumblr: http://engineering.tumblr.com
Twitter: https://engineering.twitter.com
Wanelo: http://building.wanelo.com
Yammer: http://eng.yammer.com/blog
Yelp: http://engineeringblog.yelp.com
Marek's: https://idea.popcount.org/
An aggregate of some blogs: https://www.hakkalabs.co