Uber¶

Uber (uber.com/blog/engineering) is the largest mobility platform in the world (70+ countries, 10,500 cities, 130M+ customers as of 2024) and, via Uber Eats, the largest food-delivery platform ex-China (45+ countries). The engineering org has generated an unusually rich body of public system-design writing — TChannel, Hyperbahn, Ringpop, Schemaless, M3, Jaeger, H3, RIBs, Cadence, Michelangelo, Hudi were all invented, deployed at scale, and open-sourced at Uber.

Tier classification¶

Tier 1 (pending direct RSS scraper — see raw/_feeds.yaml note "Uber pending HTML scraper" in [[AGENTS.md]]). For now the wiki reaches Uber content through secondary aggregators (High Scalability, this companies/highscalability page, Fly.io commentary) and through linked-from references in Cadence, Hudi, etc.

Architectural eras (per the 2024 Josh Clemm retrospective)¶

Era	Architecture	Primary data store
2009 LAMP	Single PHP/MySQL app, source code in Spanish	MySQL
2011 two-monolith	dispatch (Node.js) ↔ Object Node ↔ API (Python)	MongoDB → Redis / PostgreSQL
2013 SOA	API split into ~100 Python/Tornado microservices	PostgreSQL
2014 Halloween rewrite	Schemaless on MySQL; Cassandra for dispatch	MySQL (Schemaless) + Cassandra
2014 dispatch split	RTAPI Node.js gateway + new dispatch with geospatial index	+ systems/ringpop gossip
2016+ mobile	RIBs across rider / driver / Eats / Freight	—
2018 Project Ark	Consolidation: Java + Go official; Python/JS deprecated for backend; monorepo per language	—
2020 Edge Gateway	Four-layer stack: Edge / Presentation / Product / Domain	—
2021+ Fulfillment rewrite	NewSQL rewrite on Spanner	Spanner
2023+ cloud	Crane makes 4,000+ stateless microservices cloud-portable	Google + Oracle cloud

Key systems¶

In-house, open-sourced:

systems/tchannel — bi-directional RPC protocol over Hyperbahn; predates Uber's gRPC adoption.
systems/ringpop — Node.js gossip-protocol-based membership/sharding library; backbone of the 2014 dispatch rewrite.
systems/schemaless-uber — trip data store on sharded MySQL; Bigtable-shaped sparse 3D hash map.
systems/m3-uber — metrics platform (Grafana-fronted).
systems/jaeger — distributed-tracing system (evolved from Uber's earlier Merckx, Zipkin-inspired).
systems/h3-geo — hexagonal geospatial index (open-sourced to replace Google's S2 for dispatch sharding).
systems/rib-architecture — Router-Interactor-Builder mobile architecture.
systems/cadence — long-running workflow engine; the predecessor to Temporal.
systems/apache-hudi — open-source table format; built at Uber for low-latency CDC data pipelines.
systems/michelangelo — Uber's internal ML platform.

In-house, not open-sourced (microservice-platform tooling):

systems/clay-uber — Python/Flask service framework for standardized RESTful backends.
systems/flipr — feature-flag and rollout-control system.
systems/uber-dispatch — the rider-driver matching service.
systems/uber-rtapi-gateway — 2014 Node.js mobile-gateway split out of dispatch.
systems/uber-edge-gateway — 2020 four-layer gateway rewrite replacing RTAPI.
systems/uber-fulfillment-platform — 2021+ NewSQL rebuild on Spanner.
systems/project-crane — 2023+ cloud-portable infrastructure stack.

Adopted / migrated to:

Google Cloud Spanner — NewSQL store powering the 2021+ Fulfillment Platform.
systems/presto — interactive analytics on Kafka.
systems/apache-spark — scaled up for data infrastructure.

Deprecated / archived:

PostgreSQL (single-DB era, replaced by Schemaless-on-MySQL + Cassandra in 2014).
Python / JavaScript on the backend (deprecated by Project Ark, 2018+; still used for mobile/web/ML).
Tornado — Python async framework used heavily during 2013–14 SOA; deprecated with Python-on-backend.
Merckx — pre-Jaeger distributed tracing.

Architectural themes (for cross-reference)¶

service-oriented-architecture — Uber's 2013–18 microservice explosion is one of the canonical real-world examples; its reversal via Project Ark language consolidation is equally instructive.
concepts/monolith-vs-microservices-pendulum — the 2013 split + 2018 Project Ark consolidation is a textbook case.
concepts/distributed-monolith — the 2018 Project Ark framing of "thousands of microservices, 12,000 repos, 5-6 systems doing 75% the same thing" is the canonical symptom description.
traveling-salesman-problem — the TSP-variant shape of Uber's dispatch matching.
concepts/geographic-sharding — the sharding primitive under dispatch.
two-monolith-architecture — the 2011 dispatch + API split.
geospatial-gossip-sharding — 2014 dispatch rewrite: S2/H3 cells as shard key over Ringpop gossip.
layered-gateway-architecture — 2020 Edge Gateway four-tier stack.
language-consolidation-for-fleet-standardization — 2018 Project Ark's Java+Go consolidation + monorepo-per-language cleanup.

Recent articles¶

2024-03-14 — A Brief History of Scaling Uber (via High Scalability; Josh Clemm / Uber Eats, 2024-03-14) — canonical source for all eight architectural eras above. Covers the full 2009 LAMP → 2023+ Crane trajectory: two-monolith split, Halloween 2014 Schemaless rewrite, 2014 dispatch split + RTAPI + S2/Ringpop geospatial sharding, 2016+ RIB mobile, 2018 Project Ark consolidation, 2020 Edge Gateway, 2021+ Fulfillment on Spanner, 2023+ Crane cloud migration.

companies/index
companies/highscalability — aggregator through which most Uber content reaches the wiki today.