# Design a Hotel Booking Service — System Design Interview (Question + Answer) Aced (formerly Exponent) publishes a public search API over its indexed pages; the guide is at https://www.aced.io/agents/agent-access. Source: https://www.aced.io/blog/design-a-hotel-booking-service-system-design-interview-question-answer Source observed: 2026-11-05T00:11:36.356Z Last checked: 2026-11-05T00:11:36.356+00:00 Indexed: 2026-11-06T20:42:19.526+00:00 --- # Design a Hotel Booking Service — System Design Interview (Question + Answer) **Category:** [System Design](https://www.aced.io/blog/tag/system-design) **Author:** Aced Team **Last updated:** a month ago We use this interview question and answer to explore how to design a hotel booking system. The design must support multiple hotels, hotel-information management, room search, reservations, and cancellations while addressing concurrency, scalability, security, and performance. ## Functional Requirements A hotel booking system should support: - Multiple hotels. - Viewing, updating, adding, and deleting hotel information. - Searching for rooms. - Making reservations. - Cancelling reservations. One suitable approach is a microservice-based architecture with a dedicated database for each service. This approach can work for many types of businesses. ## Non-Functional Requirements The design should account for the following: - **Preventing double booking:** A cache can store available-room counts. An event queue can propagate updates to keep availability information current. - **Image storage and delivery:** We can store images in S3 and use a geographically located CDN to retrieve them, reducing storage and bandwidth demands on the application. - **Concurrency:** We should optimize how additions to the reservation table are controlled so concurrent requests do not reserve the same room. ## Back-end Approach Reservation data can require substantial storage, so the design may use multiple databases and transactional capabilities. An inventory service can coordinate with reservation and data-storage databases. A front-end experience layer can provide a common interface for different user-interface platforms. To avoid double booking, we can intelligently create identifiers and optimize the methods used to add records to the reservation table. Possible concurrency-control approaches include: - Two-phase commit. - Saga patterns. Sharding is another common optimization, although it increases the complexity of a microservice-based architecture. ## Estimation and Format For large companies, separate databases and storage for each service may be preferable despite the additional complexity. A schematic draft should outline every detail needed to satisfy the requirements list. Those requirements help estimate the cost, devices, and plan needed to build the system. ## Other Considerations The system should also be designed to: - Handle multiple currencies. - Handle multiple languages. - Integrate with multiple payment gateways. - Protect user information. - Prevent fraud. ## Continue Preparing with Aced We offer mock interviews and a [complete system design interview course](https://www.aced.io/courses/system-design-interviews?ref=exponent-blog.ghost.io). 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