Online regex tester and debugger with real-time match highlighting, detailed explanations, substitutions, unit tests, benchmarking, and code generation. Support
Joined December 2011
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Your regex now has a rubber duck that talks back 🦆
regex101’s AI assistant is now live! Your aid when you need to refine patterns, generate test cases, or work with Text Pipelines.
I’ve been following the development of LLMs with a combination of excitement and caution. Some people swear by them, while others want nothing to do with them. I can understand both, and I still find myself somewhere in the middle.
Some applications are genuinely useful, while others feel forced and, many times, pointless. Finding parts of the technology useful hasn’t made my concerns about it go away, either.
I’ve been exploring what place this could have in regex101 for quite some time, following the developments and weighing my options carefully. I take great pride in the application and the features I ship, and I care about the people who use it.
I didn’t want to add AI support just because every other app was doing it. If I was going to do it, it had to be useful, with a solid integration that made sense for regex101.
I’ve spent time testing it with a small group of users, listening to their feedback, and refining the implementation. Their experiences have helped shape what I’ve built and given me more confidence that there is something valuable here.
In the coming days, Pro subscribers of regex101 will have access to an AI assistant that can help create and refine regular expressions, as well as entire text pipelines. I believe this to be a genuinely valuable addition to the application. It is completely optional and is only engaged when you explicitly choose to use it.
I’m happy to make this available, even as my feelings about AI as a whole remain complicated. I’ll keep listening to the people using regex101 and taking care with what I build. Your feedback means a lot to me, and I would love to hear your thoughts. Please feel free to share them with in whichever way suits you best, be it here in the comments or over email.
I’ve attached a sneak peek of what you can expect in the comments.
TIL V8 can keep huge strings alive through legacy RegExp last-match state.
In short, a regex match can keep the entire input string alive -- even after you’re done using it. It stays allocated, adding unnecessary memory pressure, until another successful match replaces that state.
Since everybody loves regex so much, I’ve remade the regex quiz on the site from scratch. New and improved challenges, try it on regex101.com/quiz
Have you considered regex101 Pro but decided not to subscribe? What held you back? I’d love to hear what I could improve.
I saw this great library submission recently, and just wanted to take the opportunity to give kudos to its author, Tiago Cussiol, and share it with you all.
Super detailed description, and a 560 unit test suite to back it up: regex101.com/library/0BFrkM
Try it on regex101.com or checkout the docs: docs.regex101.com/applicatio…
You can now convert regexes between flavors directly on regex101!
Write your regex in the flavor you know best, then convert it with confidence to the flavor you need. 🔄
How do you prefer to read the changelog? Should I try to categorize it, or just keep the numbered list?
There are two "ana"s in "banana". 🍌
/ana/g only finds one.
/(?=(ana))/g captures both.
The trick: a lookahead checks ahead without consuming characters, so overlapping captures are possible.
#regex #JavaScript
