What is the regex for jwt token (strict)?

The regex pattern for jwt token (strict) is `^eyJ[A-Za-z0-9-_]+\.eyJ[A-Za-z0-9-_]+\.[A-Za-z0-9-_]+$`. This pattern validates strict jwt starting with eyj (base64 encoded json header and payload).

How do I use this regex in JavaScript?

In JavaScript, create the regex with `const regex = /^eyJ[A-Za-z0-9-_]+\.eyJ[A-Za-z0-9-_]+\.[A-Za-z0-9-_]+$/;` and test with `regex.test(yourValue)`. It returns `true` if the value matches.

How do I use this regex in Python?

In Python, use `import re; re.match(r'^eyJ[A-Za-z0-9-_]+\.eyJ[A-Za-z0-9-_]+\.[A-Za-z0-9-_]+$', value)`. The raw string prefix (`r`) prevents Python from interpreting backslashes as escape characters.

Is this regex case-sensitive?

By default, yes. To make it case-insensitive, add the `i` flag in JavaScript (`/^eyJ[A-Za-z0-9-_]+\.eyJ[A-Za-z0-9-_]+\.[A-Za-z0-9-_]+$/i`) or use `re.IGNORECASE` in Python.

Regex for JWT Token (Strict)

Regex Pattern

^eyJ[A-Za-z0-9-_]+\.eyJ[A-Za-z0-9-_]+\.[A-Za-z0-9-_]+$

Strict JWT starting with eyJ (base64 encoded JSON header and payload)

Quick Answer

The regex pattern for jwt token (strict) is `^eyJ[A-Za-z0-9-_]+\.eyJ[A-Za-z0-9-_]+\.[A-Za-z0-9-_]+$`. Strict JWT starting with eyJ (base64 encoded JSON header and payload). This works in JavaScript, Python, Ruby, PHP, Java, and most regex engines that support PCRE syntax.

Test Examples

Input	Result
eyJhbGciOiJIUzI1NiJ9.eyJzdWIiOiIxMjM0NTY3ODkwIn0.SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV	✓ Matches
notajwt	✗ No match
aaa.bbb.ccc	✗ No match
eyJ.eyJ	✗ No match

Code Examples

javascript

const regex = /^eyJ[A-Za-z0-9-_]+\.eyJ[A-Za-z0-9-_]+\.[A-Za-z0-9-_]+$/;
const isValid = regex.test(value);

python

import re
pattern = r'^eyJ[A-Za-z0-9-_]+\.eyJ[A-Za-z0-9-_]+\.[A-Za-z0-9-_]+$'
if re.match(pattern, value):
    print("valid")

ruby

pattern = /^eyJ[A-Za-z0-9-_]+\.eyJ[A-Za-z0-9-_]+\.[A-Za-z0-9-_]+$/
if value =~ pattern
  puts "valid"
end

php

if (preg_match('/^eyJ[A-Za-z0-9-_]+\.eyJ[A-Za-z0-9-_]+\.[A-Za-z0-9-_]+$/', $value)) {
    echo "valid";
}

java

String pattern = "^eyJ[A-Za-z0-9-_]+\\.eyJ[A-Za-z0-9-_]+\\.[A-Za-z0-9-_]+$";
boolean isValid = value.matches(pattern);

Frequently Asked Questions

Related Regex Patterns

UUID v4

UUID version 4 (randomly generated)

UUID (Any Version)

Any RFC 4122 UUID (versions 1-5)

JWT Token

JSON Web Token (header.payload.signature)

Hex String

Any-length hexadecimal string

Base64 String

Standard base64 encoded string

Alphanumeric Username

Username with letters, digits, underscores (3-16 chars)