You have a codebase with hundreds of tests, yet bugs still reach production. Meanwhile, the CI pipeline takes 45 minutes because the E2E suite keeps timing out on flaky browser tests. Something is ...

Imagine you are building a chat application. Users expect messages to appear the moment they are sent, not five seconds later. The simplest approach is to keep asking the server “any new messages?”...

In a traditional client-server architecture, a central server owns the data and clients request it. If the server goes down or gets overloaded, everyone is affected. A Peer-to-Peer (P2P) network fl...

In most societies, citizens elect their leaders through a voting system. Similarly, in a distributed system, servers utilize a set of algorithms to select a leader node. This process, known as “lea...

Your database handles 10,000 reads and 2,000 writes per second. One day traffic doubles. The single database server is at 95% CPU, queries are timing out, and you need a solution by Friday. You hav...

In addition to widely known SQL and NoSQL databases, such as document or key-value stores, there are specialized storage paradigms that are well-suited for specific use cases. Blob Storage Blob s...

Choosing a database is one of the most consequential decisions in system design. The two broad families, SQL (relational) and NoSQL (non-relational), make fundamentally different trade-offs around ...

Picture this: you have a counter shared between two threads, and both of them are incrementing it. You run the program expecting 2,000,000 as the final count, but instead you get something like 1,3...

Whether you are preparing for a system design interview or building production infrastructure, the same core concepts keep showing up: how data moves, where it lives, and what happens when things f...

Hashing is a process that transforms an arbitrary piece of data into a fixed-size value, typically an integer. In the context of system design, this arbitrary data could be an IP address, username,...