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Test JavaScript regular expressions, inspect matches, groups and replacements, and iterate with live sample text in the browser.
Runs locally in your browser by default — nothing is uploaded first.
Live matches, capture groups, and replacement previews will appear here.
Regex Tester runs locally in your browser by default, so you can work with the content without uploading it first.
Test JavaScript regular expressions with live sample text, match details and replacement previews in one page.
Does Regex Tester run locally or in the cloud?
Regex Tester runs locally in your browser by default, so you can work with the content without uploading it first.
What usually comes after Regex Tester?
A common next step is to continue into related workflows such as Code and Data Formatting Tools.
Is a JWT encrypted?
A standard signed JWT is not. The payload is base64url text that anyone with the token can read. Encryption requires the separate JWE format.
A JWT is three base64url segments, and decoding one tells you nothing about whether it is genuine. How to read the claims, and why tokens break in URLs.
Base64 Explained: Encoding, Padding, Data URLs, and Common MistakesA technical article on how Base64 turns bytes into text, why padding exists, how URL-safe variants differ, and why Base64 is not encryption.
Encryption Basics in the Browser: Hashing, Symmetric Keys and What Stays LocalHashing is not encryption. Symmetric encryption needs a secret both sides share. What browser-side crypto can and cannot protect.
collectionCode and Data Formatting ToolsTest JavaScript regular expressions with live sample text, match details and replacement previews in one page.
