Dispute Service Low-Level Design The dispute service manages the chargeback lifecycle: intake of issuer-initiated chargebacks, collection of merchant evidence, automated […]

Refund Service Low-Level Design The refund service is responsible for calculating how much to return to a buyer, executing the

Returns Management System Low-Level Design A returns management system (RMS) handles the reverse logistics of e-commerce: accepting return requests, generating

Checkout Service Low-Level Design The checkout service orchestrates the final steps of a purchase: reserving inventory, creating an order record,

OCR Service System Design Overview An OCR (optical character recognition) service converts images of documents, receipts, screenshots, and scanned pages

Content Classifier System Design Overview A content classifier assigns one or more category labels to user-generated content: text posts, images,

Image Recognition Service System Design Overview An image recognition service accepts raw image input, runs it through one or more

Typeahead Service System Design Overview A typeahead service extends basic search suggest by adding session context awareness, distributed prefix indexing

Search Suggest System Design Overview Search suggest (autocomplete) is one of the most latency-sensitive features in any product. Users expect

Activity Stream System Design Overview An activity stream notifies users about actions taken by others in their network: likes, follows,

Timeline Service System Design Overview A timeline service collects events from multiple heterogeneous sources, imposes a consistent ordering guarantee, and

Requirements and Constraints A risk scoring service aggregates signals from multiple data sources, runs them through an ensemble of models,

Requirements and Constraints A telemetry collector receives metrics from services and infrastructure components, aggregates them locally to reduce cardinality and

Requirements and Constraints A device registry is the source of truth for IoT device identity, credentials, configuration, and metadata. It

Requirements and Constraints An IoT data pipeline ingests telemetry from potentially millions of connected devices, processes and enriches the stream,