What is Eelgrass?
Eelgrass is a multi-tenant-by-default database engine and query language, built clean-room in Rust.
Most databases were designed single-tenant. Multi-tenancy got bolted on later with tenant_id columns or fleets of orchestrated databases. In Eelgrass the tenant is a primitive of storage, language, and types. Queries are tenant-scoped by default. Cross-tenant work uses CDC and app-layer sagas.
That design is the shift-left bet: isolation, audit history, lazy migration, forks, and change feeds leave the business layer and become engine work. Builder summary: Shift left. Business framing: Business & sales.
Founding bets
- Tenant = consistency boundary. Transactions, snapshots, forks, and residency are tenant-scoped engine operations. No cross-tenant transactions. Cross-tenant coordination is CDC + sagas.
- Storage stores values. It does not enforce types or foreign keys at write time. Meaning lives in the language layer.
- Types are a language-layer construct. Schemas are code: diffable, versioned, CI-checked. Drift surfaces as
unknown, never silent coercion. - No hand-written migration files. Edit the schema; fingerprints drive lazy apply-on-touch. Destructive changes require
@breaking. - Editor-first language. Pipe-based queries where every stage has a known shape. Autocomplete and inline errors are design inputs.
- Versioned immutable pages. Copy-on-write forks, named snapshots, and lazy migration fall out of one storage decision.
Surfaces that ship today
| Surface | Role |
|---|---|
CLI (eelgrass) | Local DB: run, serve, studio, compact, typecheck helpers |
| Studio | Local web UI over eelgrass serve |
Playground (?local=1 / play.eelgrass.dev) | In-tab wasm engine (OPFS or memory) |
@eelgrass/client | Money types, tagged template, named-query codegen |
Honest maturity
Eelgrass is pre-alpha. Status is the capability inventory. Everything else on this site describes what the code does now, with limits called out inline.