Regex Test API - Free Pattern Matcher
Applies a regular expression pattern with optional flags to a test string and returns all matches with their positions and captured groups. Supports the g, i, m, s, and u flags.
Code examples
curl -X POST https://api.botoi.com/v1/regex/test \
-H "Content-Type: application/json" \
-d '{"pattern":"\\b[A-Z0-9._%+-]+@[A-Z0-9.-]+\\.[A-Z]{2,}\\b","flags":"gi","testString":"Contact support@botoi.com or sales@botoi.com"}'When to use this API
Debug regex patterns before deploying
Test complex patterns against sample data to verify matches and capture groups before embedding them in application code.
Validate input patterns in a no-code tool
Let users define custom validation rules as regex patterns and test them against sample inputs within your app.
Extract structured data from unstructured text
Use capture groups to pull out phone numbers, dates, or IDs from log lines or scraped content.
Frequently asked questions
Which regex flags are supported?
The API supports g (global), i (case-insensitive), m (multiline), s (dotAll), and u (unicode) flags.
How are capture groups returned?
Each match includes a groups array containing the values of any parenthesized capture groups in the pattern.
Is there a timeout for complex patterns?
Yes. Patterns that take longer than 5 seconds to execute are terminated to prevent ReDoS. Simplify your pattern if you hit this limit.
Do I need to escape backslashes in the pattern?
Send the pattern as a JSON string, so backslashes need to be double-escaped (e.g., \\b for a word boundary).
Get your API key
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