Open Cron Expression Explainer
Reads the schedule back to you, and when it next fires.
Regex Explainer
Paste a regular expression and read what every part of it does, in order, with the performance traps flagged. Parsed here rather than described by a model, so it is instant and it is right.
- Not stored by NexKit
- 20,000 characters
- No sign-up
Regular expression
or paste your own — anything goes
Settings
Layout
A walkthrough with room to breathe, or one line per piece.
⌘↵ to run
What each part does
STANDING BY
This panel has nothing to do yet.
Put some text into 01 and it lands here. The sample works too, if you would rather not think of anything.
How your text is processed. Pressing Explain regex sends your text to NexKit's servers, where it is parsed and answered outright. No AI model is involved and nothing is passed to any third party. NexKit does not store what you submit, and there are no accounts to link it to.
01Using Regex Explainer
- 01
Paste the pattern
On its own, or in /pattern/flags form — both are understood.
- 02
Choose a layout
A full walkthrough, or one compact line per construct.
- 03
Read it in order
Every anchor, class, quantifier and group, explained where it appears.
What people use it for
- Understand the validation regex nobody on the team wrote
- Check a pattern before it goes near user input
- Find out why a pattern matches more than you meant
- Learn what a construct does without leaving the page
Questions
Why is this not done by an AI?
Because it does not need to be. Every construct in a regular expression has exactly one meaning, so the pattern is parsed and read back — instantly, for free, and without the chance of a model confidently describing a quantifier wrongly. The pattern is not sent to any provider.
What is catastrophic backtracking?
A repeated group that itself contains a repeat — like (a+)+ — can take exponential time on input that almost matches, hanging whatever runs it. It is the mechanism behind most ReDoS incidents. The tool flags patterns with that shape, and if yours runs on text a stranger can supply, test it with a long non-matching string.
Which flavour of regex is this?
JavaScript, which is close enough to PCRE for most patterns. Constructs specific to other engines — possessive quantifiers, atomic groups, recursion — are described where recognised, but this validates against the JavaScript engine, so a pattern it rejects may still be valid elsewhere.