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While configuring up your API check, you can run the request and its assertions using the Run request button. This will run the API check on production infrastructure and help you debug any issues.

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Basic Setup

Start by specifying the endpoint you want to track. api monitoring request configuration
  • URL: The HTTP(S) URL to monitor (e.g. https://checklyhq.com). URL’s are checked for correctness and must start with either http:// or https://.
  • Request methods: Available methods are GET, POST, PUT, HEAD, DELETE, PATCH.
  • IP family: Defaults to IPv4.
  • Skip SSL: Skip SSL certificate validation.
  • Follow redirects: Automatically follow 30x redirects.
  • This request should fail: Treat HTTP error codes (4xx and 5xx) as passed. Please note that successful responses still pass. Only failed assertions will cause the check to fail.

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Body

Add body content to your request by formatting your content as text. Selecting the type of content will automatically set the correct Content-Type header for your request.

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JSON

This option sets the Content-Type request header to application/json. Format your input as standard JSON, i.e: 
{
  "key1": "val2",
  "key2": {
    "nestedKey1": "val2"
  }
}
JSON bodies are commonly used with REST APIs.

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GraphQL

This option also sets the Content-Type request header to application/json, but allows you to type GraphQL queries and format them as such, i.e. 
query {
  allUsers {
    posts {
      id
    }
  }
}

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Form parameters

This option sets Content-Type request header to application/x-www-form-urlencoded. Format your input as a string of key/value pairs concatenated with ampersands, i.e: 
key1=value1&key2=value2
Form encodes bodies are commonly used “traditional” HTML form submissions.

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Raw data

If the predefined data types don’t work for you, use Raw data. Make sure to define your Content-Type header explicitly then.
To monitor an XML/SOAP-based API define text/xml; charset=utf-8 as Content-Type header, send your XML as Raw data and use a setup script to parse required access tokens.

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Headers

Add HTTP request headers. The type ahead feature is pre-populated with the most common headers, but you can add any custom headers you want. api monitoring HTTP headers Clicking the lock icon toggles between encrypting the value of the header on the Checkly backend and hiding it from your screen.

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Query parameters

This section allows you to add query parameters to the request URL in a structured way. You can add as many query parameters as you want. The interface is the same as for the HTTP headers: you can use the lock icon to toggle encryption and screen hiding.
You can also just leave the query parameters as part of the URL. Whatever works for you.

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Basic authentication

Add HTTP basic authentication parameters to your API request by entering a username and password in the Authentication tab.

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Accessing environment variables

Environment variables are exposed to your API checks using the common Handlebars/Moustache templating delimiters, i.e. {{USER_API_KEY}}. Note that Handlebars (double brackets) variables will be URI encoded. To avoid encoding, you can access your environment variables with triple brackets, i.e. {{{USER_API_KEY}}}. Variables can be used in the following API checks fields:
  • URL
  • Body
  • Header values
  • Query parameters values
  • Basic authentication username and password

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Using helpers and built-in variables

Next to your own variables, we’ve added some built-in ones. These variables are specific to API checks:
HelperDescription
{{GROUP_BASE_URL}}If your check belongs to a group, this resolves to the group’s configured base URL.
{{REQUEST_URL}}The request URL.
{{$UUID}}Generates a random UUID/v4, i.e. 9b1deb4d-3b7d-4bad-9bdd-2b0d7b3dcb6d.
{{$RANDOM_NUMBER}}Generates a random decimal number between 0 and 10000, i.e. 345.
{{moment}}Generates a date or time using moment.js and allows for formatting:
  • {{moment "YYYY-MM-DD"}} generates a date, i.e. 2020-08-26
  • {{moment "2 days ago" "YYYY-MM-DD"}} generates the date two days ago: 2020-08-24
  • {{moment "last week" "X"}} generates a UNIX timestamp from last week: 1597924480
A practical example of using the {{moment}} helper would be setting the pagination options on a typical API endpoint: 
 GET https://api.acme.com/events?from={{moment "last week" "X"}}&to={{moment "X"}}
For a full overview of date formatting option, check the moment.js docs.
In addition, you have access to these generic variables available to all checks:
VariableDescriptionAvailability
ACCOUNT_IDThe ID of the account the check belongs to.
CHECK_IDThe UUID of the check being executed.Only available after saving the check.
CHECK_NAMEThe name of the check being executed.
CHECK_RESULT_IDThe UUID where the result will be saved.Only available on scheduled runs.
CHECK_RUN_IDThe UUID of the check run execution.Only available on scheduled runs.
CHECK_TYPEThe type of the check, e.g. BROWSER.
PUBLIC_IP_V4The IPv4 of the check run execution.
PUBLIC_IP_V6The IPv6 of the check run execution.
REGIONThe current region, e.g. us-west-1.
RUNTIME_VERSIONThe version of the runtime, e.g, 2023.09.Only in Browser, Multistep, and API setup/teardown scripts.

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Import a cURL request

You can import the request method, url, headers and body from a cURL command. Arguments --user-agent, --cookie and --compressed also work.

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Import a Swagger / OpenAPI specification

If your API implements the Swagger 2.0 or OpenAPI spec, you can import the swagger.json spec. The importer parses your spec and prompts you to make some decisions about which requests are to be imported and how.
Light mode interface
  • Name: you can set the check name to the “description” or “url” from your spec.
  • Tags: import tags from you spec.
  • Headers: import HTTP headers from you spec.
  • Query parameters: import query parameters from your spec.
  • Add a “group” tag: Copy the name of you spec to a tag and add it to each imported request. This helps filtering and grouping related checks in the Checkly dashboard.

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Assertions

The response of an API request can be checked for correctness and timeliness by using assertions on the response data. This allows you to verify things such as:
  • HTTP response status equals 200.
  • HTTP response body equals the text “success”.
  • HTTP response time is lower than 2000 milliseconds.
  • HTTP response header “X-Custom-Header” equals “SomeValue”.
  • HTTP response JSON object has a key called “accountBalance” with a value greater than 9999.
api check assertions On each API check assertion, the following sources are available:
  • Status code: The HTTP response status, parsed as an integer.
  • JSON body: The response body parsed as a JSON object. To enable parsing, the Content-Type header of the response should be set to application/json.
  • Text body: The response body as plain text.
  • Headers: The response headers as an array of key/value pairs.
  • Response time: The response time of the full API request in milliseconds, parsed as an integer value.
For more details, see our documentation on Assertions.

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Responses

In almost all cases, you have full access to the HTTP response for assertions. We also store the full response for later retrieval and triaging issues. Response bodies are limited to a size of 25MB. Responses over this size will trigger a check failure. Additionally, if your API responds with a binary type body, i.e. a PDF or video file, we scrub the body and replace it with a short text saying that we scrubbed it. We determine the body content type by looking at the Content-Type response header. This list shows all content types that we scrub from the response data.
content type
application/pdf
audio/wave
audio/wav
audio/x-wav
audio/x-pn-wav
audio/mpeg
audio/x-ms-wma
audio/vnd.rn-realaudio
application/octet-stream
application/ogg
application/x-shockwave-flash
application/zip
video/mpeg
video/mp4
video/quicktime
video/x-ms-wmv
video/x-msvideo
video/x-flv
video/webm