Mocking & testing
53 distinct extensions were invented to do this job. Each one is a provider deciding OpenAPI would not carry something and building their own way through. Where a job has many names and few uses each, nobody won — the problem was solved privately, over and over.
53 extensions
21223 occurrences
10 vendor-named
The extensions
| Extension | What it appears to do | Uses | Providers |
|---|---|---|---|
|
x-ms-examples
vendor |
`x-ms-examples` appears on operations and on path items. Its value is a structured object. Used by 12 providers across 621 OpenAPI documents. It sits in the `x-ms-` namespace, so its meaning is define | 11723 | 12 |
| x-example | `x-example` appears on operations and on schema objects and properties. Its value is a string. Used by 28 providers across 162 OpenAPI documents. Observed values include `true`, `1`, `POST /20160918/a | 5050 | 28 |
| x-examples | `x-examples` appears on schema objects and properties. Its value is a structured object. Used by 52 providers across 160 OpenAPI documents. Consistent with mocking & testing — this is inferred from wh | 1226 | 52 |
|
x-apifox-mock
vendor |
`x-apifox-mock` appears on schema objects and properties. Its value is a string. Used by a single provider across 1 OpenAPI document. It sits in the `x-apifox-` namespace, so its meaning is defined by | 869 | 1 |
|
x-konfig-original-example
vendor |
`x-konfig-original-example` appears on schema objects and properties. Its value is a string. Used by a single provider across 1 OpenAPI document. It sits in the `x-konfig-` namespace, so its meaning i | 627 | 1 |
| x-example-object | `x-example-object` appears on response objects. Its value is a structured object. Used by a single provider across 1 OpenAPI document. Consistent with mocking & testing — this is inferred from where t | 268 | 1 |
| x-sandbox | `x-sandbox` appears on operations. Its value is a string. Used by a single provider across 1 OpenAPI document. Observed values include `enabled`, `disabled`. Consistent with mocking & testing — this i | 188 | 1 |
| x-apiary-response-examples | `x-apiary-response-examples` appears on response objects. Its value is a structured object. Used by a single provider across 1 OpenAPI document. Consistent with mocking & testing — this is inferred fr | 176 | 1 |
| x-exampleSetFlag | `x-exampleSetFlag` appears on schema objects and properties and on response objects. Its value is a boolean flag. Used by a single provider across 2 OpenAPI documents. Consistent with mocking & testin | 130 | 1 |
| x-unitTests | `x-unitTests` appears on operations. Its value is a list. Used by 5 providers across 8 OpenAPI documents. Consistent with mocking & testing — this is inferred from where the key appears and what it ca | 127 | 5 |
| x-showInExample | `x-showInExample` appears on parameter objects. Its value is a string. Used by a single provider across 11 OpenAPI documents. Observed values include `true`. Consistent with mocking & testing — this i | 98 | 1 |
| x-testEnabled | `x-testEnabled` appears on operations. Its value is a boolean flag. Used by 3 providers across 3 OpenAPI documents. Consistent with mocking & testing — this is inferred from where the key appears and | 68 | 3 |
| x-testName | `x-testName` appears on operations. Its value is a string. Used by 3 providers across 3 OpenAPI documents. Observed values include `Retrieve API Resources1`, `List Entities1`, `Create Entity1`, `Get a | 68 | 3 |
| x-testShouldPass | `x-testShouldPass` appears on operations. Its value is a boolean flag. Used by 3 providers across 3 OpenAPI documents. Consistent with mocking & testing — this is inferred from where the key appears a | 68 | 3 |
| x-testDescription | `x-testDescription` appears on operations. Its value is a string. Used by 2 providers across 2 OpenAPI documents. Observed values include `Only the fields included in the request are updated in\`, `Th | 67 | 2 |
| x-params-example | `x-params-example` appears on schema objects and properties. Its value is a string. Used by a single provider across 1 OpenAPI document. Observed values include `?program_id=d619f755-2d17-41f3-990d-c0 | 60 | 1 |
| x-fill-example | `x-fill-example` appears on parameter objects. Its value is a string. Used by 2 providers across 2 OpenAPI documents. Observed values include `no`. Consistent with mocking & testing — this is inferred | 56 | 2 |
|
x-speakeasy-test
vendor |
`x-speakeasy-test` appears on operations. Its value is a boolean flag. Used by 3 providers across 4 OpenAPI documents. It sits in the `x-speakeasy-` namespace, so its meaning is defined by speakeasy t | 40 | 3 |
| x-testConfig | `x-testConfig` appears on operations and on path items. Its value is a structured object. Used by a single provider across 1 OpenAPI document. Consistent with mocking & testing — this is inferred from | 37 | 1 |
|
x-fern-examples
vendor |
`x-fern-examples` appears on operations. Its value is a list. Used by a single provider across 1 OpenAPI document. It sits in the `x-fern-` namespace, so its meaning is defined by fern tooling rather | 27 | 1 |
| x-example-csharp | `x-example-csharp` appears on parameter objects. Its value is a string. Used by a single provider across 1 OpenAPI document. Observed values include `Status==\"ACTIVE\`, `Status==\"DRAFT\`, `Status==\ | 26 | 1 |
| x-example-php | `x-example-php` appears on parameter objects. Its value is a string. Used by a single provider across 1 OpenAPI document. Observed values include `"00000000-0000-0000-0000-000000000000"`, `& | 26 | 1 |
| x-example-java | `x-example-java` appears on parameter objects. Its value is a string. Used by a single provider across 1 OpenAPI document. Observed values include `Arrays.asList(UUID.fromString("00000000-0000-0000-00 | 25 | 1 |
| x-sandbox-name | `x-sandbox-name` appears on parameter objects. Its value is a structured object. Used by a single provider across 24 OpenAPI documents. Consistent with mocking & testing — this is inferred from where | 24 | 1 |
| x-authorization-example | `x-authorization-example` appears on security schemes. Its value is a string. Used by a single provider across 22 OpenAPI documents. Observed values include `Bearer 1000.41d9xxxxxxxxxxxxxxxxxxxxxxxxc2 | 22 | 1 |
|
x-speakeasy-usage-example
vendor |
`x-speakeasy-usage-example` appears on operations. Its value is a structured object. Used by 9 providers across 9 OpenAPI documents. It sits in the `x-speakeasy-` namespace, so its meaning is defined | 19 | 9 |
| x-example-python | `x-example-python` appears on parameter objects. Its value is a string. Used by a single provider across 3 OpenAPI documents. Observed values include `True`, `False`. Consistent with mocking & testing | 18 | 1 |
| x-example-ruby | `x-example-ruby` appears on parameter objects. Its value is a string. Used by a single provider across 1 OpenAPI document. Observed values include `Status==#{XeroRuby::Accounting::Account::ACTIVE}`, ` | 18 | 1 |
| x-ads_command_line_example | `x-ads_command_line_example` appears on operations. Its value is a string. Used by a single provider across 2 OpenAPI documents. Observed values include `curl -v "https://developer.api.autodesk.com/os | 13 | 1 |
|
x-ds-examples
vendor |
`x-ds-examples` appears on operations. Its value is a list. Used by a single provider across 1 OpenAPI document. It sits in the `x-ds-` namespace, so its meaning is defined by ds tooling rather than b | 9 | 1 |
| x-faker | `x-faker` appears on schema objects and properties. Its value is a string. Used by a single provider across 1 OpenAPI document. Observed values include `internet.password`, `commerce.productName`, `da | 9 | 1 |
| x-sandbox-only | `x-sandbox-only` appears on operations. Its value is a boolean flag. Used by a single provider across 1 OpenAPI document. Consistent with mocking & testing — this is inferred from where the key appear | 7 | 1 |
| x-example-literal | `x-example-literal` appears on operations. Its value is a string. Used by a single provider across 1 OpenAPI document. Observed values include `| 4 |
1 |
|
| x-sandbox-id | `x-sandbox-id` appears on parameter objects. Its value is a structured object. Used by a single provider across 4 OpenAPI documents. Consistent with mocking & testing — this is inferred from where the | 4 | 1 |
| x-config-always-visible-in-example | `x-config-always-visible-in-example` appears on parameter objects. Its value is a boolean flag. Used by a single provider across 1 OpenAPI document. Consistent with mocking & testing — this is inferre | 3 | 1 |
|
x-speakeasy-example
vendor |
`x-speakeasy-example` appears on security schemes. Its value is a string. Used by 3 providers across 3 OpenAPI documents. It sits in the `x-speakeasy-` namespace, so its meaning is defined by speakeas | 3 | 3 |
| x-limited-example | `x-limited-example` appears on schema objects and properties. Its value is a string. Used by a single provider across 1 OpenAPI document. Observed values include `flex`. Consistent with mocking & test | 2 | 1 |
|
x-postman-example
vendor |
`x-postman-example` appears on parameter objects. Its value is a string. Used by a single provider across 1 OpenAPI document. It sits in the `x-postman-` namespace, so its meaning is defined by postma | 2 | 1 |
|
x-tyk-test
vendor |
`x-tyk-test` appears on header objects. Its value is a string. Used by a single provider across 1 OpenAPI document. It sits in the `x-tyk-` namespace, so its meaning is defined by tyk tooling rather t | 2 | 1 |
| x-api-version-header-example | `x-api-version-header-example` appears in the info block. Its value is a string. Used by a single provider across 1 OpenAPI document. Observed values include `2026-04-30`. Consistent with mocking & te | 1 | 1 |
| x-commonExamples | `x-commonExamples` appears in components. Its value is a structured object. Used by a single provider across 1 OpenAPI document. Consistent with mocking & testing — this is inferred from where the key | 1 | 1 |
| x-convelio-example | `x-convelio-example` appears on security schemes. Its value is a string. Used by a single provider across 1 OpenAPI document. Observed values include `token {{secret_token}}`. Consistent with mocking | 1 | 1 |
| x-fatcat-ident-example | `x-fatcat-ident-example` appears at the root of the document. Its value is a string. Used by a single provider across 1 OpenAPI document. Observed values include `&FATCATIDENTEXAMPLE`. Consistent with | 1 | 1 |
| x-fatcat-uuid-example | `x-fatcat-uuid-example` appears at the root of the document. Its value is a string. Used by a single provider across 1 OpenAPI document. Observed values include `&FATCATUUIDEXAMPLE`. Consistent with m | 1 | 1 |
| x-issn-example | `x-issn-example` appears at the root of the document. Its value is a string. Used by a single provider across 1 OpenAPI document. Observed values include `&FATCATISSNEXAMPLE`. Consistent with mocking | 1 | 1 |
| x-md5-example | `x-md5-example` appears at the root of the document. Its value is a string. Used by a single provider across 1 OpenAPI document. Observed values include `&FATCATMD5EXAMPLE`. Consistent with mocking & | 1 | 1 |
| x-onesignal-flat-notification-example | `x-onesignal-flat-notification-example` appears on operations. Its value is a boolean flag. Used by a single provider across 1 OpenAPI document. Consistent with mocking & testing — this is inferred fr | 1 | 1 |
| x-orcid-example | `x-orcid-example` appears at the root of the document. Its value is a string. Used by a single provider across 1 OpenAPI document. Observed values include `&FATCATORCIDEXAMPLE`. Consistent with mockin | 1 | 1 |
| x-sandbox-name-not-required | `x-sandbox-name-not-required` appears on parameter objects. Its value is a structured object. Used by a single provider across 1 OpenAPI document. Consistent with mocking & testing — this is inferred | 1 | 1 |
| x-sha1-example | `x-sha1-example` appears at the root of the document. Its value is a string. Used by a single provider across 1 OpenAPI document. Observed values include `&FATCATSHA1EXAMPLE`. Consistent with mocking | 1 | 1 |
| x-sha256-example | `x-sha256-example` appears at the root of the document. Its value is a string. Used by a single provider across 1 OpenAPI document. Observed values include `&FATCATSHA256EXAMPLE`. Consistent with mock | 1 | 1 |
| x-test-notification | `x-test-notification` appears on parameter objects. Its value is a structured object. Used by a single provider across 1 OpenAPI document. Consistent with mocking & testing — this is inferred from whe | 1 | 1 |
| x-tokenUrl-sandbox | `x-tokenUrl-sandbox` appears on security schemes. Its value is a string. Used by a single provider across 1 OpenAPI document. Observed values include `https://demo.salv.com/oauth/token`. Consistent wi | 1 | 1 |
Work with this as data
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