Most systems bury their state machine in code, where it cannot be inspected, verified or safely evolved. We make it a first-class artifact across its whole lifecycle — and every tool on this site is tagged with the stage it belongs to.
Anything that occupies a situation and moves between them on events is a state machine — whether or not anyone drew it as one. It is the hardest software to get right, and it is everywhere.
orders, billing, subscriptions, approvals NServiceBus, Particular Software
replication, consensus, consistency Amazon S3/DynamoDB, Azure Cosmos DB, MongoDB, Datadog, PingCAP, Elastic, Yandex ClickHouse
pre-silicon & chip verification Intel
SCADA, PLCs, factory automation
motion planning, task sequencing
perception → decision → actuation
flight control, avionics modese.g. OpenComRTOS — formally-designed RTOS
a pump that free-flows, a scanner stuck between modes
settlement, ledgers, trade lifecycle
call state, session & consensus protocols Informal Systems — Quint/TLA+, IBC
grid control, battery & plant management
fulfillment, routing, inventory
…and everything with a “mode”
Model states, actions, and transitions explicitly — with contracts and invariants that capture what the system must and must never do.
Check machines against their contracts before they ship: reachable-state analysis, invariant checking, and replay of real traces against the model.
Run fleets of machines with visibility into every instance's state, safe version migrations, and compatibility gates for every change.
Change a live system without breaking it — versioned machine definitions, validated migrations, and gates that catch incompatibilities before deployment.
The tools are grouped by the same four stages, and the services put them into a team.