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JWT (JSON Web Token)Regex — Pattern, Examples & Code

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

What it matches / doesn't match

Matches ✅Does not match ❌
●eyJhbGciOiJIUzI1NiJ9.eyJzdWIiOiJ1c2VyIn0.abc123●not.a.jwt!
●eyJ0eXAiOiJKV1QiLCJhbGciOiJSUzI1NiJ9.e30.sig●onlytwoparts.here
●has spaces in.the.token

How it works

Matches the three-segment structure of a JWT: header, payload, and signature, each encoded in Base64URL (A–Z, a–z, 0–9, _, -). The signature segment may be empty for unsecured tokens (alg: none). This pattern validates structural format only — use a JWT library to verify the signature and claims.

Code Usage

JavaScript

const regex = /^[A-Za-z0-9_-]+\.[A-Za-z0-9_-]+\.[A-Za-z0-9_-]*$/;
regex.test("eyJhbGciOiJIUzI1NiJ9.eyJzdWIiOiJ1c2VyIn0.abc"); // true

Python

import re
pattern = re.compile(r'^[A-Za-z0-9_-]+\.[A-Za-z0-9_-]+\.[A-Za-z0-9_-]*$')
bool(pattern.match("eyJhbGciOiJIUzI1NiJ9.eyJzdWIiOiJ1c2VyIn0.abc"))  # True

Go

import "regexp"
r := regexp.MustCompile(`^[A-Za-z0-9_-]+.[A-Za-z0-9_-]+.[A-Za-z0-9_-]*$`)
r.MatchString("eyJhbGciOiJIUzI1NiJ9.eyJzdWIiOiJ1c2VyIn0.abc") // true

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FAQ

What does the JWT (JSON Web Token) regex pattern match?

Matches the three-segment structure of a JWT: header, payload, and signature, each encoded in Base64URL (A–Z, a–z, 0–9, _, -). The signature segment may be empty for unsecured tokens (alg: none). This pattern validates structural format only — use a JWT library to verify the signature and claims.

How do I use the JWT (JSON Web Token) regex in JavaScript?

const regex = /^[A-Za-z0-9_-]+\.[A-Za-z0-9_-]+\.[A-Za-z0-9_-]*$/; regex.test("eyJhbGciOiJIUzI1NiJ9.eyJzdWIiOiJ1c2VyIn0.abc"); // true

Can I use the JWT (JSON Web Token) regex in Python?

Yes. import re pattern = re.compile(r'^[A-Za-z0-9_-]+\.[A-Za-z0-9_-]+\.[A-Za-z0-9_-]*$') bool(pattern.match("eyJhbGciOiJIUzI1NiJ9.eyJzdWIiOiJ1c2VyIn0.abc")) # True