There are many regex syntax, one different from the other: .Net regex, Java regex, PHP/PCRE regex, Python regex. etc.

Some sites for checking & testing regex expressions are just great - like Regex101 or RegExr [that is mentioned on InDesignSecrets grep resources], but it has different languages/syntax.

For example: The RegExr supports only JavaScript and PHP/PCRE. But the Regex Storm supports only .Net.

On what exact syntax the InDesign grep is based on? Thanks you very much for your kind help.

Edit: to be more clear - on regular-expressions.info it is called 'regular expression engine' or 'regular expression flavor'. So what is the InDesign 'regular expression flavor'?

  • I just can assume that 'InDesign grep flavor' is PCRE (Perl based): just trying to use 'R' expression (=Recursion) and this one worked great on InDesign. And it is not supported on all engines. Feb 17, 2019 at 8:02

1 Answer 1


I have got an answer for this question on the Adobe forum. This what is says:

According to Peter Kahrel's title "GREP in InDesign 3rd Edition" (ISBN: 978-0-9825083-6-7) - InDesign’s GREP uses the Boost libraries; information on these libraries is available from www.boost.org, especially Perl Regular Expression Syntax - 1.67.0

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