How we capture real production database traffic at Airbnb and replay it offline to load-test, plan capacity, and de-risk upgrades.By: Zuofei Wang, Erluo LiIntroductionAt Airbnb, MySQL-compatible databases are a critical backbone of our online database infrastructure: a fleet of hundreds of clusters supporting thousands of use cases at millions of queries per second (QPS). Operating databases at scale brings hard problems, including sizing clusters for future growth, keeping behavior consistent across version upgrades and migrations, and reproducing production incidents well enough to debug…
How Airbnb uses proximity signals to personalize without relying on individual user history.By: Wei Jiang, Bin Xu, Bharathi Thangamani, Weiwei Guo, Sundar Srinivasavaradhan, Tracy Yu, Huiji Gao, Swapnil Ghike, Michael KinotiGreat personalization starts with knowing your user. But what happens when the user is a stranger?A significant share of Airbnb users arrive without a login, without a recent search history, or without any prior booking — especially those landing from paid advertising or organic search. For these users, the ML models that power search ranking, destination recommendations,…
How two new Chronon capabilities, Push Mode and NRT Model Transform, allows us to provide more relevant search results instantly as a guest explores, rather than waiting for the next batch run.By: Pengyu Hou, Yuli Han, Daochen Zha, Haozhen Ding, Xin Liu, Sophie Wang, Pallavi Adusumilli, Sherry Li, Henry Saputra, Chun How Tan, Huiji Gao, Yan Zhang, Stephanie Moyerman, Yi Li, and Sanjeev KatariyaA guest’s interaction with Airbnb doesn’t pause to wait for a nightly batch job. Someone might browse a dozen listings on a Tuesday afternoon, run a new search that evening, and expect the next search…
How Airbnb’s agent harness transforms unstructured data exploration by encoding scientific methodology into scalable, reproducible, and audit-ready infrastructure.Wren DoughertyAsk a coding agent to analyze 100,000 customer support conversations and within minutes you’ll have a polished taxonomy, precise prevalence numbers, and an executive-ready summary. What you can’t see is the investigation that produced them: the methods it chose, the evidence it weighed, how much to trust it, or whether a second request would agree. All that reaches you is the polish. The model is undeniably…
Project Lighthouse — Part 3: Introducing project-lighthouse-anonymizeThe data in Project Lighthouse is powered by privacy-preserving anonymization code. We’ve put this code into open source, and published two new technical papers detailing the scalable algorithms and data quality frameworks behind it.By: Adam BloomstonIntroductionIn 2020, we launched Project Lighthouse, which we developed in partnership with leading civil rights and privacy organizations. As our 2020 announcement details, Project Lighthouse enables us to measure potential disparities in user experiences. This work uses…
When we retrain, when we rebuild, and when we leave a model alone.By: Harrison KatzA forecast that carries weightThe Forecasting Data Science team at Airbnb produces many of the forecasts the rest of the company plans around: demand, bookings, cancellations, and a range of finer cuts by market and segment, refreshed continuously across thousands of markets. The targets differ, and the models differ, but they have one thing in common: Other teams build on top of them.This means a forecast that is casually wrong is not a clean miss, as it might be in an academic setting. That’s because a small…
Rebuilding login and signup surfaced product insights, not just technical challenges. Here’s how we designed Flexible Authentication at the intersection of product intuition and technical architecture.By: Jose Santos, Mike BarryFor Airbnb, logins at irregular intervals are normal. A guest books a trip in January and may not open the app again until summer. A host checks back only when a reservation comes in, and may be busy with other activities when it does. For a two-sided marketplace where a failed login means a lost booking, and lost revenue for both the guest and the host, long gaps…
How Airbnb teams build trustworthy Generative AI products by treating evaluation as a first-class engineering discipline; not an afterthought.Nestled into the lush hillside, this stunning modern retreat features striking natural wood architecture, terraced balconies, and a serene landscape.By: Rohit Girme, Dan Miller, Mia Zhao, Lifan Yang, Clint KellyIntroductionGenerative AI breaks a lot of the assumptions that used to hold true for software testing. Unlike traditional software, LLM outputs are non-deterministic, and “correct” is subjective. Because so much judgment is involved, you often…
How we built a Transformer-based sequence model that encodes years of guest behavior to surface the right listings at the right time.By: Daochen Zha, Chun How Tan, Xin Liu, Bin Xu, Han Zhao, Xiaowei Liu, Jun Shi, Tracy Yu, Hui Gao, Huiji Gao, Liwei He, Michael Kinoti, Stephanie Moyerman, and Sanjeev KatariyaIntroductionPlanning a trip on Airbnb rarely happens in a single session. A guest searching for a place to stay in San Francisco might browse dozens of listings over several days, leaving behind a trail of views. Typically, over a period of years, that same guest will have accumulated many…
Training an LLM is the easy part. The hard part is designing experiments and evaluations that you can trust enough to know whether the new model is actually an improvement.By: Baharak SaberidokhtIntroductionShipping a production LLM system means iterating fast on improvements to something that is, by construction, non-deterministic. Models drift, judges disagree with themselves, references regenerate as different strings, and bugs may persist until the next release, because retraining takes weeks. Most of this friction comes from infrastructure challenges, not model quality, and the fixes…
How Airbnb’s data engineers and analytics engineers built a consistent and flexible data modeling framework to support the expansion into Homes, Experiences, and Services.By: Patrick Lam, Namrata Lamba, Jamie StoberWith the May 2025 Summer Release, Airbnb redesigned its app, relaunched Experiences, and debuted Services, pushing us beyond our traditional Homes focus. For the data teams, this meant rapidly evolving a decade-old infrastructure to integrate two brand-new product pillars. Our data engineers and analytics engineers rose to the challenge by building a consistent and flexible…
How Airbnb built a Kubernetes sidecar to deliver dynamic configuration reliably at scale.By: Bo Teng, Cosmo Qiu, Siyuan Zhou, Ankur Soni, Xin Huang, Willis HarveyIntroductionIn our previous post, we explored Airbnb’s dynamic configuration system, Sitar, with a focus on service architecture and configuration change safety. Now for the harder question: once a config change is committed, which happens several times each minute, how does it actually reach the thousands of Airbnb’s service instances reliably, quickly, and without redeploying the services?This post describes sitar agent: a…
How Airbnb used sequential geographic recovery signals and prior propagation to generate reliable corridor-level forecasts when local data was scarce.By: Harrison KatzThe problem with unprecedented shocksAlmost every forecasting system is built on the same implicit assumption: the future will resemble the past. You train on historical data, you validate on holdout periods, and you trust that past patterns will at least roughly indicate future performance. When this assumption breaks, the model does not gracefully degrade; it fails confidently. It produces precise, well-calibrated intervals…
How Airbnb shifts from PaaS to an internal knowledge graph infrastructure at scale.By: Lucen Zhao, Shukun Yang, Ashish JainKnowledge graphs offer a natural and powerful way to represent relationships between entities. Many real-world systems are fundamentally about connections.Airbnb’s identity graph captures relationships between users in a graph database. The identity graph serves aggregated insights that enable user identity resolution and relationship understanding. These capabilities support a wide range of Trust and Safety use cases, from detecting suspicious activities to identifying…
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