openapi: 3.1.0
info:
  title: NATS Monitoring HTTP Accounts Subscriptions API
  description: The NATS server exposes a monitoring HTTP endpoint that provides real-time server statistics including connection info, route details, subscription data, JetStream metrics, and health checks for observability and operations.
  version: 2.10.0
  contact:
    name: NATS.io
    url: https://nats.io/
  license:
    name: Apache 2.0
    url: https://www.apache.org/licenses/LICENSE-2.0
servers:
- url: http://localhost:8222
  description: Default NATS monitoring endpoint
tags:
- name: Subscriptions
paths:
  /subsz:
    get:
      summary: Subscription information
      operationId: getSubsz
      tags:
      - Subscriptions
      description: Reports detailed information about current subscriptions and the routing data structure.
      parameters:
      - name: subs
        in: query
        schema:
          type: boolean
      - name: offset
        in: query
        schema:
          type: integer
      - name: limit
        in: query
        schema:
          type: integer
      - name: test
        in: query
        schema:
          type: string
      responses:
        '200':
          description: Subscription details
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Subsz'
components:
  schemas:
    Subsz:
      type: object
      properties:
        num_subscriptions:
          type: integer
        num_cache:
          type: integer
        num_inserts:
          type: integer
        num_removes:
          type: integer
        num_matches:
          type: integer
        cache_hit_rate:
          type: number
        max_fanout:
          type: integer
        avg_fanout:
          type: number