Distributed systems form the backbone of modern large-scale computing, from cloud platforms to distributed databases and large clusters.
As a PhD student, you need resources that go beyond the basics, combining strong theoretical foundations with practical insights. And ideally, they should be freely accessible.
The following five books are all legally available online at no cost and are well-suited to accompany you through graduate-level research in distributed systems.
Distributed Systems (4th Edition) — Maarten van Steen & Andrew S. Tanenbaum
This modern classic offers a broad and rigorous introduction to distributed systems, covering architectures, communication, naming, coordination, replication, fault tolerance, and security. The 4th edition updates many examples to reflect today’s large-scale systems and is widely used in advanced undergraduate and graduate courses. A personalized digital copy is available for free from the authors’ website.
Access the free digital edition
Distributed Systems for Fun and Profit — Mikito Takada
Short, opinionated, and surprisingly deep, this book is great when you want to quickly grasp the core concepts behind real-world distributed systems. It walks through consistency models, time and ordering, replication strategies, and the design of systems like Dynamo and Bigtable, always with an eye toward what matters in practice. Its informal style makes it perfect as a first pass or as a companion to more formal texts.
The Datacenter as a Computer: Designing Warehouse-Scale Machines (3rd Edition) — Luiz André Barroso, Urs Hölzle, Parthasarathy Ranganathan
If you’re doing a PhD, you’ll likely care about how your algorithms and systems behave at data-center scale. This open-access book treats an entire datacenter as a single “warehouse-scale computer” and explains how to design, operate, and optimize such systems. It’s particularly valuable for understanding the hardware, energy, and reliability constraints behind large distributed services such as those run by major cloud providers.
Download the open-access book (PDF and more)
Operating Systems: Three Easy Pieces — Remzi H. Arpaci-Dusseau & Andrea C. Arpaci-Dusseau
While technically an operating-systems book, OSTEP is essential background for anyone doing serious work in distributed systems. Its deep treatment of concurrency, synchronization, and persistence provides the building blocks that distributed algorithms and storage systems rely on. The clear structure, numerous exercises, and freely available PDFs make it ideal for self-study alongside more specialized distributed-systems material.
Access the free online textbook and PDFs
Distributed Algorithms — Jukka Suomela
These lecture notes form a full-fledged graduate-level textbook on distributed algorithms, focusing on rigorous models and proofs. Topics include locality, symmetry breaking, graph problems, and complexity in distributed settings, making it an excellent bridge between theory and the systems-oriented books above. If your PhD work touches consensus, graph algorithms on networks, or lower bounds in distributed computing, this text is a highly relevant free resource.
Download the lecture-notes textbook as PDF
Also check out my other free book articles:
https://www.sickgaming.net/blog/2025/11/...must-read/