JWT Generator | Online Free Tool | Elysia Tools

Tool usage guide

Learn when to use this tool, what it supports, and how real users apply it.

Key facts

Category: Security
Input types: text, select, number, textarea, checkbox
Output type: text
Sample coverage: 4
API ready: Yes

Overview

Generate signed JSON Web Tokens (JWT) instantly using customizable HMAC algorithms and payload claims. This tool allows developers to configure standard header fields, timestamps, and custom JSON payloads to create secure authentication tokens for local development, API testing, and debugging.

When to use

Mocking authenticated requests to test backend endpoints in Postman, cURL, or local test suites.
Debugging signature verification issues across HMAC algorithms like HS256, HS384, and HS512.
Prototyping custom claim schemas with role-based access control data before implementing authorization services.

How it works

1Enter a signing secret key (minimum 8 characters) and select the desired HMAC algorithm (HS256, HS384, or HS512).
2Specify standard claims such as Issuer (iss), Subject (sub), Audience (aud), and token lifetime in seconds (exp).
3Provide optional custom payload attributes formatted as valid JSON and toggle timestamp claims like iat, nbf, or jti.
4Click generate to produce a bare compact JWT string or a formatted report detailing token headers, payload, and signature.

Use cases

Generating short-lived bearer tokens to test OAuth2/OIDC consumer services and API gateways.
Creating mock administrative tokens with elevated permission arrays for role-based frontend route testing.
Simulating future-valid tokens using the Not Before (nbf) claim to test clock-skew tolerance and activation guards.

Examples

1. API Gateway Mock Token

Backend Engineer

Background

Testing protected microservice routes locally without running a full identity provider service.

Problem

Needs a valid HS256 signed bearer token containing user identity and tenant metadata for endpoint authorization tests.

How to use

Enter the shared secret, define the subject and issuer, set the expiration to 3600 seconds, and add tenant information in the custom claims JSON field.

Secret: super-secret-key-12345
Algorithm: HS256
Issuer: api.example.com
Subject: usr_987654
Expires In: 3600
Custom Claims: {"tenantId": "org_abc123", "role": "developer"}
Include iat: true

Outcome

Generates a compact HS256 JWT string containing tenantId and role claims ready to insert into the Authorization header.

2. Extended Security Admin Token

QA Automation Specialist

Background

Validating that high-privilege administrative endpoints reject expired tokens and enforce SHA-512 signatures.

Problem

Requires an HS512 token with an explicit JWT ID (jti) and Not Before (nbf) constraint for automated integration testing.

How to use

FAQ

Which signing algorithms are supported?

The generator supports HMAC-based symmetric signing algorithms: HS256 (SHA-256), HS384 (SHA-384), and HS512 (SHA-512).

What is the minimum requirement for the secret key?

The secret key is mandatory and must contain at least 8 characters to ensure standard cryptographic strength.

How are expiration (exp) and issued-at (iat) timestamps handled?

If an expiration value in seconds is provided, the tool calculates the Unix epoch timestamp by adding those seconds to the current time. The iat claim records the exact timestamp of token creation when enabled.

Can I include nested objects or arrays in custom claims?

Yes, any valid JSON structure entered in the Custom Claims field is parsed and merged into the JWT payload.

What is the difference between bare output and the detailed report?

Enabling 'Output JWT Only' returns just the compact three-part token string (header.payload.signature), while disabling it outputs decoded headers, claims, and security details.

Secret: enterprise-signing-secret-key-2026
Algorithm: HS512
Subject: admin_root
Expires In: 1800
Custom Claims: {"scope": ["read:all", "write:all", "delete:records"], "admin": true}
Include jti: true
Include nbf: true

JWT Generator

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Learn when to use this tool, what it supports, and how real users apply it.

Key facts

Overview

When to use

How it works

Use cases

Examples

1. API Gateway Mock Token

2. Extended Security Admin Token

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