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Regex Replace Tester

Preview a bounded regular-expression replacement locally and export its exact text output.

Replacement preview26 chars
A bounded JavaScript-style pattern, without lookarounds or backreferences.
g i m s u
Up to 20,000 characters. The preview shows at most 1,000 matches.
Use $&, $1–$99, $<name>, or $$; $` and $' are intentionally refused.
Live replacement output Ready
28 output chars
last, first and world, hello
Processed on your device

How it works & useful details

Preview a controlled replacement

Replacement output supports literal text, $$, $&, numbered captures $1–$99, and named captures $<name>. The live preview and exported text use the same bounded transform.

Source-copy tokens $` and $' are refused because repeated matches can multiply output. The regex safety rules from the Match Tester apply here too.

Private, bounded text processing

Code and markup stay as inert text in this browser. These tools do not execute JavaScript, render HTML, load URLs, install packages, contact registries, or save what you paste.

Regex patterns are limited to 500 characters and test text to 20,000 characters. Formatters and package inspection accept up to 100,000 characters; exports are capped at 200,000 characters.