Platform
API management for engineering orgs — versioned internal APIs, owned by teams, consumed with explicit permissions, accessible from AI agents and CI.
Spec0 is an API management platform for the internal APIs that wire your engineering org together. The audience is the engineers who build, publish, and consume those APIs — not external partners. The product is the multi-tenant web app at spec0.io; everything visible in the dashboard is also reachable through the CLI and the public REST API.
What it does, in one paragraph
A team in your org publishes an API to the registry. Other teams in the same org subscribe to that API with explicit permissions on the operations they need to call. The owning team's admin reviews and approves. Versions are tagged and immutable; subscribers receive change logs, breaking-change notifications, and producer announcements without anyone scraping Slack or chasing email. Every action is auditable, every consumer is visible, every API has an owner — leadership gets a bird's-eye view of the API mesh, individual teams get governance without ceremony.
Four primitives
APIs
Versioned, immutable OpenAPI specs owned by a team. Publish, govern, version, mock — the operational centre of the registry.
Teams
Who owns what. Org → team → user; team admins approve subscriptions on the APIs they own.
Subscriptions
A consumer team's permission grant on a producer team's operations. The seam Spec0 grows into an authorization control plane (roadmap).
Events
Change logs, breaking changes, and publisher announcements — flowing off active subscriptions into the inbox.
How the pieces fit
┌─────────┐ owns ┌──────────┐
│ Team │ ────────────────────▶ │ API │
└─────────┘ └──────────┘
▲ │ publishes
│ member of ▼
┌─────────┐ subscribes to ┌──────────┐
│ User │ ──────────────────▶ │ Spec │ (immutable, tagged)
└─────────┘ └──────────┘
▲ │ provisions
│ receives ▼
┌─────────┐ fires ┌──────────┐
│ Event │ ◀────────────────────│ Mock │
└─────────┘ └──────────┘A Team owns APIs. An API publishes immutable Specs. Each Spec provisions a Mock. Subscriptions and lifecycle changes emit Events into Users' inboxes.
How teams use it day to day
- GitOps-friendly. Own the spec in git, gate publishes through CI with the CLI and the block-on-breaking-changes recipe, tag with the commit hash. The dashboard is the read surface; CI is the write surface.
- AI-native. Your org's APIs, specs, change logs, and consumer relationships are reachable from any MCP-aware agent (Cursor, Claude, Continue) — same API key the CLI uses, no second auth layer to wire up. The org-scoped tool surface is on the roadmap; the public-docs MCP is live today.
- Mock for free. Every API can have a team-owned mock server — multiple response variants per operation, conditional selection via CEL. OSS self-hosted or managed SaaS.
What's not on these pages
- The CLI — every UI action has a non-interactive equivalent in
spec0. - The Mock server — see Mock server for the engine; the platform's role here is provisioning, not request handling.
- The agent surface — see Agents for MCP setup (and ADRs 11/12 for the auth + topology design behind it).
- Authorization for runtime API calls — foundation in place, end-to-end feature still in development. See the Subscriptions roadmap.