JWT Decoder
Read a token's header and claims locally.
Never uploadedTest a pattern against real text and see every match, group and index as you type.
No surrounding slashes needed - just the expression.
Global, ignore case, multiline, dotall and unicode.
Every match is highlighted in context and listed with its index and capture groups.
JavaScript's, since it runs on the browser's own engine. Most syntax is shared with PCRE, but lookbehind, named groups and unicode property escapes can differ - check your target language if the pattern is going elsewhere.
Without it, only the first match is found. With it, the pattern scans the whole input. This tool always scans so you can see everything, but the flag still reflects the semantics you would get in code.
Usually an unescaped special character. Dots, plus signs, question marks, parentheses and brackets all have meaning - escape them with a backslash to match them literally.
A badly nested pattern can backtrack catastrophically. This tool caps the scan so a runaway pattern degrades rather than freezing the tab, but the same pattern would still be dangerous in production.
Test a regular expression against real text and watch every match highlight as you type, with each capture group and character index listed underneath. The engine is the browser's own, so this is JavaScript regex semantics - mostly shared with PCRE, though lookbehind, named groups and unicode property escapes are worth double-checking if the pattern is destined for another language. The scan is capped so a catastrophically backtracking pattern degrades instead of freezing the tab, though such a pattern remains dangerous in production.
The last couple are from other categories - there are 81 tools here in total.
Read a token's header and claims locally.
Never uploadedFormat, validate and minify JSON instantly.
Never uploadedEncode or decode Base64, UTF-8 safe.
Never uploadedRandom v4 UUIDs, as many as you need.
Never uploadedShrink PDFs to fit email, chat, or upload limits.
Shrink JPG, PNG or WebP without visible quality loss.
Never uploaded