How Airbnb Evolved from a Ruby Monolith to Hybrid Micro‑Macro Services

Airbnb Architecture Evolution

Jessica Tai, a software engineering manager at Airbnb, presented a detailed overview of how the company's architecture has changed over the years.

The talk covered topics such as the shift to microservices, collaboration challenges, migration hurdles, technical snippets (e.g., Slack using Kafka, pair‑programming anti‑patterns, an introduction to GPU programming with OpenGL), and more.

Three Major Stages

Since its founding, Airbnb has gone through three primary architectural phases:

Monolith (2008‑2017) : A Ruby on Rails monolithic application where most engineers were full‑stack and could deliver end‑to‑end features quickly.

Microservices (2017‑2020) : The company split into four service types—data acquisition, business logic, workflow orchestration, and UI aggregation—each owned by a single team to avoid ownership conflicts.

Microservices + Macroservices (2020‑present) : A hybrid model that combines many microservices into larger macro‑services, providing a unified API surface while preventing the data aggregator from becoming a new monolith.

Monolith (2008‑2017)

In the early years, Airbnb’s Ruby on Rails monolith allowed rapid product development because full‑stack engineers could work on any part of the codebase. As the company grew, the number of engineers, teams, and lines of code increased dramatically, leading to ownership ambiguity, tight coupling, slow deployments (sometimes taking over a day), and reduced developer efficiency.

Microservices (2017‑2020)

Learning from monolith pain points, Airbnb introduced four distinct service categories and assigned each service to a single owning team. This change also altered team structures: instead of full‑stack teams, engineers specialized in specific stacks (e.g., data services or business‑logic services). A dedicated migration team built tools and shared best practices for moving from the monolith to microservices. However, managing the growing number of services and their dependencies became a new challenge.

Microservices + Macroservices (2020‑present)

To address collaboration difficulties, Airbnb adopted a hybrid approach where macro‑services aggregate multiple microservices behind a unified API. The internal backend fetches data from a data‑aggregation layer, which then communicates with various service blocks, each encapsulating a set of microservices.

Engineers are careful to keep the data aggregator from becoming another monolith by strictly defining service boundaries and data ownership.