Martin Fowler is the personal site of software author Martin Fowler, with articles on software architecture, refactoring, agile and design patterns, popular with engineers.
Joel on Software is Joel Spolsky's blog about software development, management and startups, known for essays such as The Joel Test and the founding of Stack Overflow.
Coding Horror is Jeff Atwood's blog about programming and software culture, written by a co-founder of Stack Overflow, with thoughtful essays for developers.
Overreacted is Dan Abramov's personal blog on React, JavaScript and software engineering, with in-depth, approachable essays by a former member of the React team.
Julia Evans is the blog and zine site of programmer Julia Evans, who writes clear, illustrated explanations of Linux, networking, debugging and programming topics.