URL Uptime Checker

openapi: 3.1.0
info:
  title: URL Uptime Checker
  description: Checks whether a website or web address is currently reachable and reports how fast it responded.
  version: 1.0.0
  contact:
    name: _done
    url: https://forms.gle/5KzuSFH7p8hHtDmz7
    email: info@underscoredone.com
  x-openapi-url: https://url-uptime-checker.underscoredone.com/openapi.json
  x-logo:
    url: https://underscoredone.com/logo.png
    altText: _done
  x-guidance: Call this before treating any URL as reachable. Pass the full web address including http:// or https://. Read
    the 'up' field for a simple yes/no, 'status_code' for the response code, 'response_time_ms' for speed, and 'error' for
    the reason if it failed. Do not retry automatically on timeout unless explicitly instructed.
  x-ai-instructions: Call this before treating any URL as reachable. Pass the full web address including http:// or https://.
    Read the 'up' field for a simple yes/no, 'status_code' for the response code, 'response_time_ms' for speed, and 'error'
    for the reason if it failed. Do not retry automatically on timeout unless explicitly instructed.
  x-provider: _done — single-purpose utility APIs for developers and AI agents. Pay per call with USDC on Base Mainnet or
    Solana Mainnet.
  x-pricing:
    model: pay-per-call
    currency: USDC
    network: Base Mainnet or Solana Mainnet
    price: $0.01
  x-keywords:
  - network
  - url uptime checker
  - website status
  - reachability check
  - uptime monitor
  - url validator
  - site down detector
  - http status check
  - utility
  - api
  - ai-agent
  - pay-per-call
  - usdc
  - x402
  x-category: website uptime
  x-provider-url: https://underscoredone.com
  x-agentcash-auth:
    mode: paid
  x-402:
    price: $0.01
    network: eip155:8453
    asset: '0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913'
    pay_to: '0xE9740820225B3918b4ddd1292C7cA4Ca0e2C2F08'
    facilitator: https://api.cdp.coinbase.com/platform/v2/x402
    scheme: exact
    description: Checks whether a website or web address is currently reachable and reports how fast it responded.
    mime_type: application/json
    networks:
    - network: eip155:8453
      asset: '0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913'
      pay_to: '0xE9740820225B3918b4ddd1292C7cA4Ca0e2C2F08'
    - network: solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp
      asset: EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v
      pay_to: 8ugAWAXDB8V18kiUrGZTq1oMvU3C6Fxs8hfC6rvzQT3b
paths:
  /check:
    post:
      tags:
      - website uptime
      - uptime
      - is site down
      - url uptime
      - uptime checker
      - website monitoring
      - is website reachable
      - site availability
      - uptime monitor
      - website health
      - ping url
      - response time check
      - site up or down
      - heartbeat check
      - sla monitoring
      summary: Checks if a given web address is currently online and reachable.
      description: Checks a web address to see if it is currently online, how fast it answered, and where it ended up after
        any redirection.
      operationId: handler_check_post
      requestBody:
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/Request'
        required: true
      responses:
        '200':
          description: Successful response
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Response'
              examples:
                success:
                  summary: Successful response
                  value:
                    api_version: 1.0.0
                    url: https://example.com
                    up: true
                    status_code: 200
                    response_time_ms: 184
                    final_url: https://example.com/
                    redirected: false
                    error: null
                    checked_at: '2026-07-23T04:12:09Z'
        '422':
          description: Unprocessable — a required field is missing or the wrong type. Check the detail field for specifics.
          content:
            application/json:
              schema:
                type: object
                properties:
                  detail:
                    type: array
        '402':
          description: Payment required. Send a signed USDC payment on Base Mainnet or Solana Mainnet using the x402 protocol.
          headers:
            X-Payment-Response:
              description: x402 payment challenge — base64-encoded JSON with payment details.
              schema:
                type: string
        '400':
          description: Bad request — your input failed validation or could not be processed. Check the detail field for specifics.
          content:
            application/json:
              schema:
                type: object
                properties:
                  detail:
                    type: string
      x-ai-instructions: Call this before treating any URL as reachable. Pass the full web address including http:// or https://.
        Read the 'up' field for a simple yes/no, 'status_code' for the response code, 'response_time_ms' for speed, and 'error'
        for the reason if it failed. Do not retry automatically on timeout unless explicitly instructed.
      x-guidance: Call this before treating any URL as reachable. Pass the full web address including http:// or https://.
        Read the 'up' field for a simple yes/no, 'status_code' for the response code, 'response_time_ms' for speed, and 'error'
        for the reason if it failed. Do not retry automatically on timeout unless explicitly instructed.
      x-payment-info:
        price:
          fixed:
            mode: fixed
            currency: USD
            amount: '0.01'
        protocols:
        - x402: {}
components:
  schemas:
    HTTPValidationError:
      properties:
        detail:
          items:
            $ref: '#/components/schemas/ValidationError'
          type: array
          title: Detail
      type: object
      title: HTTPValidationError
    Request:
      properties:
        url:
          type: string
          title: Url
          description: The full web address to check, starting with http or https.
        follow_redirects:
          type: boolean
          title: Follow Redirects
          description: Whether to follow the site to its final address if it sends you somewhere else, before reporting the
            result.
          default: true
        method:
          type: string
          enum:
          - GET
          - HEAD
          title: Method
          description: Which kind of check to run. GET reads the whole page. HEAD only checks that the site answers, which
            is quicker.
          default: GET
      type: object
      required:
      - url
      title: Request
      example:
        follow_redirects: true
        method: GET
        url: https://example.com
    Response:
      properties:
        api_version:
          type: string
          title: Api Version
          description: The version of this service that answered the request.
          default: 1.0.0
        url:
          type: string
          title: Url
          description: The web address that was checked, exactly as it was given.
        up:
          type: boolean
          title: Up
          description: True if the site answered at all, false if it could not be reached.
        status_code:
          anyOf:
          - type: integer
          - type: 'null'
          title: Status Code
          description: The reply code the site sent back, if it answered.
        response_time_ms:
          anyOf:
          - type: integer
          - type: 'null'
          title: Response Time Ms
          description: How many thousandths of a second the site took to answer, if it answered.
        final_url:
          anyOf:
          - type: string
          - type: 'null'
          title: Final Url
          description: The address the site ended up at after any redirection, if it answered.
        redirected:
          type: boolean
          title: Redirected
          description: True if the site sent you somewhere else before answering.
        error:
          anyOf:
          - type: string
          - type: 'null'
          title: Error
          description: A short plain reason the check failed, or nothing if it succeeded.
        checked_at:
          type: string
          title: Checked At
          description: The exact date and time the check was performed.
      type: object
      required:
      - url
      - up
      - redirected
      - checked_at
      title: Response
      example:
        api_version: 1.0.0
        checked_at: '2026-07-23T04:12:09Z'
        final_url: https://example.com/
        redirected: false
        response_time_ms: 184
        status_code: 200
        up: true
        url: https://example.com
    ValidationError:
      properties:
        loc:
          items:
            anyOf:
            - type: string
            - type: integer
          type: array
          title: Location
        msg:
          type: string
          title: Message
        type:
          type: string
          title: Error Type
        input:
          title: Input
        ctx:
          type: object
          title: Context
      type: object
      required:
      - loc
      - msg
      - type
      title: ValidationError
  securitySchemes:
    siwx:
      type: apiKey
      in: header
      name: SIGN-IN-WITH-X
      description: CAIP-122 wallet signature for repeat access after payment
servers:
- url: https://url-uptime-checker.underscoredone.com
  description: Production
tags:
- name: website uptime
- name: uptime
- name: is site down
- name: url uptime
- name: uptime checker
- name: website monitoring
- name: is website reachable
- name: site availability
- name: uptime monitor
- name: website health
- name: ping url
- name: response time check
- name: site up or down
- name: heartbeat check
- name: sla monitoring
x402Version: 2
x-payment-accepts:
- scheme: exact
  network: eip155:8453
  payTo: '0xE9740820225B3918b4ddd1292C7cA4Ca0e2C2F08'
  asset: '0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913'
- scheme: exact
  network: solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp
  payTo: 8ugAWAXDB8V18kiUrGZTq1oMvU3C6Fxs8hfC6rvzQT3b
  asset: EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v