openapi: 3.0.1
info:
  title: LLM Guard Output System API
  description: Self-hostable REST API for LLM Guard, Protect AI's open-source (Apache 2.0) security toolkit for LLM interactions. The llm-guard-api service wraps the llm-guard Python library in a FastAPI application and exposes scanners that detect, redact, and sanitize prompts and outputs for prompt injection, PII, toxicity, secrets, banned topics, and more. Scanners are configured per deployment via scanners.yml. This specification documents the real self-hosted API surface; Protect AI's commercial products (Guardian, Recon, Layer) do not publish a public REST API and are not modeled here.
  termsOfService: https://protectai.com/terms
  contact:
    name: Protect AI / LLM Guard
    url: https://llm-guard.com/
  license:
    name: Apache 2.0
    url: https://www.apache.org/licenses/LICENSE-2.0
  version: '1.0'
servers:
- url: http://localhost:8000
  description: Default local llm-guard-api deployment (FastAPI/Uvicorn).
security:
- bearerAuth: []
- {}
tags:
- name: System
paths:
  /:
    get:
      operationId: getRoot
      tags:
      - System
      summary: Service metadata.
      description: Returns basic service and version information for the running LLM Guard API.
      responses:
        '200':
          description: OK
          content:
            application/json:
              schema:
                type: object
                additionalProperties: true
  /healthz:
    get:
      operationId: getHealthz
      tags:
      - System
      summary: Liveness probe.
      description: Returns the liveness status of the API process.
      responses:
        '200':
          description: Service is alive.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/HealthStatus'
  /readyz:
    get:
      operationId: getReadyz
      tags:
      - System
      summary: Readiness probe.
      description: Returns readiness once scanners are loaded and the API can serve scan requests.
      responses:
        '200':
          description: Service is ready.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/HealthStatus'
  /metrics:
    get:
      operationId: getMetrics
      tags:
      - System
      summary: Prometheus metrics.
      description: Exposes Prometheus-format metrics for the API when metrics are enabled.
      responses:
        '200':
          description: Metrics in Prometheus text exposition format.
          content:
            text/plain:
              schema:
                type: string
components:
  schemas:
    HealthStatus:
      type: object
      properties:
        status:
          type: string
          example: ok
  securitySchemes:
    bearerAuth:
      type: http
      scheme: bearer
      description: Optional bearer token authentication, enabled per deployment via the llm-guard-api configuration. Deployments may also run without auth.