Regex

POST/v0/regex

Validates a regular expression pattern. Checks whether the pattern compiles successfully with the given flags. Returns the list of named capture groups found in the pattern.

Request Body (JSON)

Field	Type	Required	Description
pattern	string	Yes	The regular expression pattern to validate
flags	string	No	Regex flags (e.g. `gi`, `ms`). Valid flags: `d`, `g`, `i`, `m`, `s`, `u`, `v`, `y`

Example Request

curl -X POST https://api.isvalid.dev/v0/regex \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"pattern": "^(?<year>\\d{4})-(?<month>\\d{2})-(?<day>\\d{2})$", "flags": "i"}'

Response Fields

Field	Type	Description
valid	boolean	Whether the pattern is a valid regular expression
pattern	string	The pattern as provided
flags	string \| null	The flags used for validation
namedGroups	string[]	List of named capture groups found in the pattern
error	string	Error message when the pattern is invalid (only present when `valid` is `false`)

Example Response — valid

{
  "valid": true,
  "pattern": "^(?<year>\\d{4})-(?<month>\\d{2})-(?<day>\\d{2})$",
  "flags": "i",
  "namedGroups": ["year", "month", "day"]
}

Example Response — invalid

{
  "valid": false,
  "error": "Invalid regular expression: /[/: Unterminated character class"
}