A deterministic, versioned state machine database with WAL-backed durability

Modern systems cannot replay or audit semantic state evolution.

When a payment fails, an order gets stuck, or a workflow breaks — teams dig through scattered logs, reconstruct timelines manually, and hope they find the root cause. State changes are buried in application code, spread across services, and lost to time.

The consequences:

• Auditors can't verify what happened and when
• Compliance teams can't prove process adherence
• Engineers can't reproduce bugs from production
• Recovery from failures requires guesswork

rstmdb is a deterministic, versioned state machine database with a Write-Ahead Log.

You define state machines declaratively. rstmdb persists every transition, enforces guard conditions, and maintains a complete, replayable history of how each entity evolved.

{
  "states": ["pending", "approved", "rejected"],
  "initial": "pending",
  "transitions": [
    {
      "from": "pending",
      "event": "APPROVE",
      "to": "approved",
      "guard": "ctx.score > 80"
    },
    { "from": "pending", "event": "REJECT", "to": "rejected" }
  ]
}

Every state change is durable, versioned, and replayable.

Every state transition is recorded with full context. Answer "what happened to entity X?" instantly, with cryptographic proof.

Enforce business rules at the database level. Guard conditions ensure transitions only happen when allowed. The audit trail is built-in.

Replay any entity's history from the WAL. Reproduce bugs, verify behavior, test migrations — all from production data.

Crash recovery is automatic. The WAL ensures no acknowledged write is ever lost. Deterministic replay rebuilds state exactly.

Define allowed states and transitions using a simple JSON DSL. Add guard expressions to enforce business rules. Version your definitions for safe evolution.

Every mutation is written to a durable, append-only log before acknowledgment. Segment-based storage with CRC32C checksums ensures integrity.

On startup, rstmdb replays the WAL to reconstruct state. Any point in history can be materialized. Event sourcing is native.

Machine definitions are versioned. Instances are bound to specific versions. Evolve your state machines without breaking existing workflows.

# Docker
docker run -p 7401:7401 rstmdb/rstmdb:latest

# From source
cargo install rstmdb
rstmdb --config config.yaml

rstmdb uses an open-core model with the Business Source License 1.1.

Free for:

• Development and testing
• Non-production environments
• Evaluation and research
• Production on a single node

Commercial license required for:

• Multi-node production deployments
• Managed service offerings (SaaS/DBaaS)

Each release converts to Apache 2.0 after 4 years, becoming fully open source.

We believe in building sustainable open source. BSL lets us invest in the project while keeping the code available and eventually free for everyone.

• Documentation
• Architecture
• Roadmap
• Contributing

Deterministic state. Durable history. Auditable by design.