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What Redis is
Redis describes itself as an in-memory data store used as a cache, vector database, document database, streaming engine, and message broker, with built-in replication, configurable on-disk persistence, and atomic operations defined on complex data types.
More precisely for the roles Synedrix OS assigns it: Redis is a data structure server. Everything the OS gets from it is a consequence of a small set of primitives: strings, hashes, sets, sorted sets, streams, key expiry, and atomic operations.
Two delivery contracts are documented explicitly and differ: pub/sub is at-most-once and fire-and-forget, while Streams with consumer groups are at-least-once and replayable.
What it is normally used for
How Redis is used generally, before Synedrix OS enters the picture.
- Caching: strings plus TTLs in front of a slower system of record
- Session storage and short-lived working data where sub-millisecond reads matter
- Rate limiting and counters using atomic increments with expiry
- Message broking and event fan-out via pub/sub or Streams
- Job queues, including as the execution broker for n8n's own queue mode
What it owns, and what it does not
Every platform in the stack has a non-overlapping responsibility. The boundary is as much a part of the design as the capability.
Owns
- Hot state: short-lived working data
- Pub/sub broadcast
- Idempotency keys: a key that makes a retry safe
- Rate-limit counters
- Heartbeats
- Deduplication windows
Does not own
- Canonical business state, policies, approvals, audit trails
- → Supabase PG17 (Layer 7)
- Time-series records and temporal aggregations
- → QuestDB (Layer 7)
- Lineage, influence and relationship graphs
- → Neo4j (Layer 7)
- Semantic retrieval and similarity search
- → Qdrant (Layer 7)
- The event record itself
- → Layer 8, per the Event Taxonomy Standard
Why Redis
Redis already does exactly what's needed, out of the box
Preventing an action from happening twice, rate limiting, and heartbeats aren't extra features that have to be built; they come directly from a few basic Redis commands: setting a value only if it doesn't already exist, expiring keys automatically, and incrementing counters.
Check-and-act happens safely, in one step
Redis can check a condition and act on it in a single, uninterruptible step, either directly or through a small script it runs atomically. That's exactly what's needed for governance checks where two things happening at once could cause a mistake.
Governance checks are too fast to be worth skipping
Every governed action passes through a policy check, a duplicate check, and a rate limit first. Those checks need to be fast enough that nobody is ever tempted to bypass them for speed, which is what an in-memory store is for.
It is the smallest platform in the stack
Redis runs as a single process with nothing else to install or connect to. For an air-gapped deployment, having fewer moving parts is genuinely useful.
Licence position
Redis questions, answered
Short, citable answers drawn from this page.
What role does Redis play in Synedrix OS?
Redis (Coordination bus) is mapped to Layer 7: Memory & Data in Synedrix OS. Safe retries and rate limits come from Redis's own primitives, not from features built on top.
What does Redis own in Synedrix OS?
Redis owns: Hot state: short-lived working data; Pub/sub broadcast; Idempotency keys: a key that makes a retry safe; Rate-limit counters; Heartbeats; Deduplication windows.
What does Redis not own in Synedrix OS?
Redis does not own: Canonical business state, policies, approvals, audit trails (owned by Supabase PG17 (Layer 7)); Time-series records and temporal aggregations (owned by QuestDB (Layer 7)); Lineage, influence and relationship graphs (owned by Neo4j (Layer 7)); Semantic retrieval and similarity search (owned by Qdrant (Layer 7)); The event record itself (owned by Layer 8, per the Event Taxonomy Standard).
What licence is Redis under?
Redis is released under Version-dependent: see note. Redis 7.2 and earlier are BSD 3-Clause. Redis 7.4 to 7.8 are dual RSALv2 or SSPLv1. Redis 8.0+ adds AGPLv3 as a third option. Redis states that RSALv2 and SSPLv1 are not open source licences; only the AGPLv3 option is OSI-approved. Because the licence changed across versions, choosing a Redis version is also choosing a licence.
The full reference page, with the operating model, deployment detail, and links to every canonical specification this platform touches, lives in the documentation repository, which is private while the platform is being built.