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Defining Custom Linter Rules

Linting against custom rules is useful in standardizing and keeping API definitions clean.

Let’s see how to enforce a custom rule to validate an email address filed to check if it is a corporate email address.

    "rules": {
        "wso2-email-rule": {
            "description": "Should be a WSO2 email.",
            "given": "$",
            "severity": "error",
            "then": {
                "field": "",
                "function": "pattern",
                "functionOptions": {
                    "match": "^[a-z][email protected]$"

Here we introduce a new rule “wso2-email-rule” to check whether the email address at the $ path contains any matches to the regex pattern "^[a-z][email protected]$". If it does not match, the violation of the custom rule will be listed with a severity level “error”.


The custom ruleset should be in accordance with the schema used in Stoplight Spectral custom rulesets and should be defined in JSON.