Interactive Tool
Client-Side RE2 Validation
RE2 Regex Pattern Tester
Test and validate your regular expressions against sample search queries and URLs before pasting them into Google Search Console’s Performance report filters.
GSC Syntax
RE2 Incompatibility Detected: This pattern uses lookarounds (
?=, ?!) or backreferences (\1), which Google Search Console’s RE2 engine will reject with an evaluation error.
Evaluation Results
RE2 Engine Constraints in Google Search Console
Google Search Console’s performance filtering runs on Google’s open-source RE2 engine. RE2 enforces linear execution time to protect service availability.
Allowed RE2 Syntax:
- Case-insensitive flag:
(?i) - Alternation:
cat|dog - Word boundaries:
\b - Quantifiers:
+,*,?,{2,4}
Forbidden / Unsupported in RE2:
- Positive lookahead:
(?=...) - Negative lookahead:
(?!...) - Lookbehind assertions:
(?<=...) - Backreferences:
\1,\2