> ## Documentation Index > Fetch the complete documentation index at: https://vastai-80aa3a82-auto-openapi-update-8483c1e9.mintlify.site/llms.txt > Use this file to discover all available pages before exploring further. # Create User Webhook > Register a new webhook URL for the authenticated user, subscribing it to the specified event types. ## OpenAPI ````yaml /api-reference/openapi.yaml post /api/v0/webhooks/ openapi: 3.1.0 info: title: Vast.ai API description: >- Vast.ai REST API for managing GPU cloud instances, machine operations, and AI/ML workflows. ## AI Agent Quick-Start Install the CLI skill for your agent (Claude Code, Cursor, Windsurf, etc.): npx skills add vast-ai/vast-cli CLI reference: https://raw.githubusercontent.com/vast-ai/vast-cli/master/vastai/SKILL.md SDK reference: https://raw.githubusercontent.com/vast-ai/vast-cli/master/vastai_sdk/SKILL.md ## Auth All endpoints require `Authorization: Bearer $VAST_API_KEY`. Get your key at: https://cloud.vast.ai/manage-keys/ ## Key Quirks - `gpu_ram` in CLI = GB; in REST API = MB (CLI auto-converts) - SSH keys must be registered BEFORE creating an instance (VM: no recovery; Docker: can add post-create) - `onstart` field is limited to 4048 characters -- gzip+base64 for longer scripts - `POST /api/v0/asks/{id}/` (create instance) returns `new_contract` as the instance ID, not `id` - Poll trap: if `actual_status` becomes `exited`, `unknown`, or `offline` it will never reach `running` -- destroy and retry version: 1.0.0 contact: name: Vast.ai Support url: https://discord.gg/vast servers: - url: https://console.vast.ai description: Production server security: - BearerAuth: [] paths: /api/v0/webhooks/: post: tags: - Accounts summary: Create User Webhook description: >- Register a new webhook URL for the authenticated user, subscribing it to the specified event types. requestBody: content: application/json: schema: type: object properties: webhook_url: type: string description: >- HTTPS URL to receive webhook event deliveries; must start with 'https://', have a valid hostname, and be at most 2048 characters. example: https://example.com/vastai-hook event_types: type: array description: >- List of notification slug strings (e.g. 'low_disk_space' or 'host:low_disk_space') this webhook should receive; must be non-empty and contain only known slugs. example: - low_disk_space - near_end_date name: type: string description: >- Optional human-readable display label for this webhook (max 120 characters, no control characters). example: My integration responses: '200': description: >- Success; returns {success: true, webhook: object, enabled_notification_preferences: list}; webhook includes webhook_secret (shown once) content: application/json: schema: type: object properties: success: type: boolean description: Always true on success. webhook: type: object description: >- The created webhook object including id, user_id, name, webhook_url, event_types, created_at, updated_at, and the one-time webhook_secret. properties: id: type: integer description: Webhook ID. user_id: type: integer description: Owning user ID. name: type: string description: Optional display name. webhook_url: type: string description: The registered HTTPS endpoint URL. event_types: type: array items: type: string description: Subscribed event type slugs. created_at: type: number description: Unix timestamp of creation. updated_at: type: number description: Unix timestamp of last update. webhook_secret: type: string description: >- Signing secret for verifying webhook payloads; returned only at creation time. enabled_notification_preferences: type: array items: type: string description: >- List of preference keys (e.g. 'host:low_disk_space') that were automatically enabled for webhook delivery. example: success: true webhook: id: 42 user_id: 1001 name: My Webhook webhook_url: https://example.com/vastai-events event_types: - low_disk_space created_at: 1700000000 updated_at: 1700000000 webhook_secret: abc123secretkey enabled_notification_preferences: - host:low_disk_space '400': description: >- Bad request; possible messages: 'webhook_url is required and must be a string', 'webhook_url must use HTTPS', 'webhook_url exceeds maximum length of 2048 characters', 'webhook_url must include a hostname', 'webhook_url has an invalid port', 'event_types must be a list', 'event_types must contain at least one event type', 'Unknown event type: ', 'Duplicate event type: ', "Maximum of 4 webhooks per user", 'This webhook URL is already registered' content: application/json: schema: $ref: '#/components/schemas/Error' security: - BearerAuth: [] components: schemas: Error: type: object properties: error: type: string msg: type: string securitySchemes: BearerAuth: type: http scheme: bearer description: API key must be provided in the Authorization header ````