Work Breakdown Structure The project hierarchy flows from top to bottom: Project → Epics → Stories → Tasks. Each node […]

Query Cache Low-Level Design A query cache stores database query results in fast storage (typically Redis) so repeated identical queries

Database Proxy Low-Level Design A database proxy sits in the network path between application servers and the database. It multiplexes

Report Builder Low-Level Design A report builder lets non-engineers define, save, schedule, and share data reports without writing raw SQL.

Data Import Service Low-Level Design A data import service ingests user-supplied files into the system's database. The main challenges are:

Data Export Service Low-Level Design A data export service lets users extract large datasets in their preferred format. The core

Continuous Profiler Low-Level Design A continuous profiler measures where a production service spends CPU time without requiring code changes or

Error Tracking Service Low-Level Design An error tracking service answers two questions: “What broke?” and “Has it broken before?” It

Log Pipeline Low-Level Design A production log pipeline moves log data from every host and container to durable storage where

Rollout Schema A feature flag with gradual rollout has the following core fields: { flag_id: “checkout-v2”, rollout_plan: [ {percentage: 1,

Object Types A version control system stores three object types in a content-addressed object store: Blob: raw file content. The

Pull Request Model A pull request (PR) represents a request to merge a source branch into a target branch. Core

Data Model: Shapes A whiteboard is a collection of shapes. Each shape is a flat record: { id: “uuid”, type:

Tax Service Components A production tax calculation service has five distinct responsibilities: nexus determination (does the business owe tax in

Escrow Model An escrow service acts as a neutral third party: the buyer transfers funds to a platform-controlled escrow account,