Yes, but with gaps.
The 2nd edition (2023) covers modern topics like LLM-based search design and event-driven architectures. Older free PDFs are from 2019–2020 and miss these.
What the book does well:
What it lacks (compared to GitHub resources):
Some brilliant repos take the designs from HTSDI and implement minimal working code. For example:
These give you executable architecture—far more powerful than static diagrams.
The best PDFs on GitHub are not textbooks; they are transcripts of failed interviews.
Engineers who passed FAANG interviews often upload their preparation notes, explicitly referencing HTSDI chapters. You will find gems like: