SubstratThe hard parts, hosted.

A runtime-enforced substrate for building vertical B2B SaaS — tenancy, permissions, audit, and GDPR live below your API surface, so code built at AI speed can't break them.

What is Substrat?

Getting started

🛡️

Enforcement, not conventions

Generated code cannot cross a tenant boundary, skip the audit log, or mislabel an event — the guarantees are properties of the substrate, not rules you remember to follow.

🏢

Nested B2B tenancy, first-class

Tenants contain scopes (branches, client companies, brands), each an isolated database with its own permissions. Users hold roles at any node of the tree.

⚙️

Engines you don't have to write

Hardened domain machinery — work orders, invoicing — that owns the invariants (state machines, append-only history, immutable exports) while your vertical owns vocabulary, workflows, and UI.

🤖

Designed for AI-built verticals

A narrow, aggressively typed SDK where invalid states don't typecheck, self-describing module manifests, and contract tests that push back mechanically instead of via prompting.

💾

Runs anywhere the contract runs

Every kernel contract ships a pure-SQLite adapter alongside the production one. Local dev and CI run real kernel semantics — one .sqlite file per scope, no cloud account.

📜

Audit and GDPR built in

Every mutation emits a kernel-stamped event with a mandatory PII classification, keyed for crypto-shredding erasure from day one.