Input JSON
{
"operation": "regex_test",
"pattern": "^[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,}$",
"input": "sample@example.invalid"
}Attest tools · Developer utilities: cron, regex, UUID, slug and JSON
Test a regex for email
Test a simple email-shaped pattern against a reserved example-domain address; a pattern match does not verify mailbox delivery.
Captured output JSON
{
"operation": "regex_test",
"pattern": "^[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,}$",
"flags": "",
"engine": "RE2 via re2js 2.8.6 (MIT)",
"input_length": 22,
"matched": true,
"full_match": true,
"match_count": 1,
"more_matches": false,
"limit": 20,
"program_size": 13,
"group_count": 0,
"named_groups": [],
"matches": [
{
"index": 0,
"length": 22,
"text": "sample@example.invalid",
"text_truncated": false,
"groups": [],
"named_groups": {}
}
],
"limits": {
"max_pattern_length": 2000,
"max_input_length": 100000,
"max_matches": 100,
"max_capture_groups": 20,
"max_match_text": 500,
"max_program_work": 100000000
},
"notes": [
"RE2 has no backtracking, so the patterns that hang JavaScript's engine — (a+)+$ and its relatives — cannot blow up here. RE2 is not free, though: its search cost grows with the size of the compiled program (program_size below) multiplied by the length of the input, and a bounded repeat such as {1000} makes that program large. A pattern whose program_size x input_length would pass max_p (truncated)",
"\\w, \\d, \\s and \\b are ASCII-only in RE2. Use \\p{L}, \\p{N} or \\p{Alpha} for the Unicode classes.",
"index and length are in UTF-16 code units, the same units as JavaScript's String.prototype.slice, so a caller can cut the match out of their own input."
],
"notice": "General information only, computed from the caller's own input. Nothing sent here is stored.",
"checked_at": "2026-10-20T20:47:47.589Z"
}API call
curl -s -X POST https://getattest.com.au/api/v1/dev \
-H "authorization: Bearer $ATTEST_API_KEY" \
-H "content-type: application/json" \
--data-raw '{"operation":"regex_test","pattern":"^[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,}$","input":"sample@example.invalid"}'Run this call with your own bearer key. Issue an API key.
About this example
The input was validated and run locally through the registered service. The output above is a display preview of the captured service result. File bytes are described instead of printed, and strings longer than 400 characters are truncated; the HTTP API also adds call_id, credits_charged and credits_remaining. Timestamps and generated identifiers will vary.
Source: apps/api/svc/dev_utils.mjs