How FAANG-Scale Frontend Teams Actually Work

A frontend organisation of two thousand engineers is a different kind of thing from a team of twenty, in the same way a city is a different kind of thing from a house. The build must be hermetic because nobody can hold the dependency graph in their head; the framework must enforce patterns because nobody can review every component; the data layer must mask what a component may read because nobody can audit every query. Every piece of machinery exists because a human process stopped scaling, and knowing which process tells you whether you need the machinery.

Ten parts: the org shape, monorepos and hermetic builds (Bazel, Buck, Nx at scale), internal frameworks and what they add over React, state and data layers (Relay, GraphQL, RPC, data masking), design-system distribution with codemods and deprecation at scale, experimentation with guardrails and holdouts, performance budgets and release trains, code review and the quality culture around ownership and lint as policy, on-call for a frontend, and the libraries these companies wrote (React, Relay, Recoil, Jest, Flow, Hermes, Fresco, Lexical) and the problem each one answered.