A number of companies have tech blogs that are more than just self-aggrandizement or PR.

Google

Google is the champion. I have no idea how many tech blogs they have. Here are the ones I know about. I have no doubt that there are others.

• Official Google Blog
• Google Public Policy Blog
• Google Student Blog
• Official Android Blog
• Google Chrome Blog
• Google Lat Long. The official blog for Google Maps.
• Google Developers Blog
• Google Ads Developer Blog
• Android Developers Blog
• Google Testing Blog
• YouTube Engineering and Developers Blog
• Official Google for Work Blog
• Google Open Source Blog
• Research Blog. Google Research Blog.
• Google Cloud Platform Blog

Google also does research and publishes research articles

• Research at Google

Microsoft

I’m sure this is only scratching the surface. That said, Microsoft is still only a sometime tech blogger, most of their communication is in tech docs, magazines and books, or in PR pieces.

• The Official Microsoft Blog
• TN Home - TechNet Blogs
• MSDN Blogs
• Windows Blog

Netflix

Netflix is moderately unique when it comes to tech blogging, its blogs exist to describe its internal technology; it develops all its tech to run its infrastructure, and releases large portions as open source.

• The Netflix Tech Blog

As part of their semi-open stance, they have a unified open source presence/portal on Github.

• Netflix Open Source Software

The community put this summary description of their software stack together

• Netflix’s Tech Stack

GitHub

• GitHub Engineering
• The GitHub Blog: Engineering

Facebook

• Engineering Blog
• Research at Facebook

Apple

I don’t think Apple has any tech blogs.

IBM

There are a lot, I should track them down. Most of IBM’s technical content is not presented in blogs, but in sources like developerWorks.

Assorted

• Atlassian: Atlassian Developers
• Cockroach Labs: Blog | Cockroach Labs
• Dropbox: Dropbox Tech Blog
• eBay: eBay Tech Blog
• Heroku: Heroku Engineering Blog
• Instagram: Instagram Engineering
• LinkedIn: LinkedIn Engineering
• PayPal: PayPal Developer
• Pinterest: Pinterest engineering blog
• Riot Games: Riot Games Engineering
• Spotify: Spotify | Labs. Spotify’s Engineering and Technology Blog.
• Square: The Corner. Square Engineering Blog.
• StackOverflow: Stack Overflow Blog
• StackShare: StackShare. StackShare Blog
• Yahoo: Yahoo Engineering

Reference

kilimchoi/engineering-blogs. A curated list of engineering blogs

SlicedHam. Aggregated dev blog posts from all over the web.

Thoughtworks