Build and sign a JWT online 12 uses
Build and HMAC-SHA256-sign a JWT from a header, payload, and secret, instantly in your browser.
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- Runs entirely in your browser — your secret is never sent to a server
- HMAC-SHA256 signing via the browser's native Web Crypto API
- Free, no account required
How it works
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1
Paste the text, code, or token you want to encode or decode.
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2
Conversion happens instantly as you type.
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3
Review the result, including any decoded structure.
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4
Copy the result to your clipboard.
Why use this tool
Every dev utility, one place
Format, convert, encode, decode, and generate — no more juggling ten tabs.
100% private, always
Every tool runs in your browser — your code and data are never sent anywhere.
Works on any device
Runs on Windows, Mac, Linux, iOS, and Android — nothing to install.
Instant results
No queues, no build step — results update as you type.
Built to handle real data
Full Unicode support and RFC-compliant parsing, edge cases included.
Free, always
Free to use, with no rate limits, sign-up, or trial period.
Frequently asked questions
The tool strictly utilizes the HMAC SHA-256 (HS256) algorithm for robust security.
This specific utility is designed for simpler symmetric shared-secret encoding, not asymmetric key pairs.
Yes, the header is pre-configured to denote HS256 and the JWT typing.
No, the secret is wiped the moment you close the tab, keeping your application credentials secure.
It assumes you have structured your JSON payload correctly and will encode whatever you provide.
From the blog
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Base64 is everywhere in modern web development, from data URIs to authentication headers. Here is a deep dive into how it works and common pitfalls to avoid.
Demystifying JSON: How to Troubleshoot Common Parsing Errors
JSON is the backbone of web APIs, but syntax mistakes can halt your code. Here is how to identify and fix missing commas, unescaped strings, and trailing characters.
Stop Pasting Secrets Into Random Websites: A Developer's Security Checklist
Every day developers paste API keys, JWTs, and credentials into online tools without a second thought. Here's why that habit is riskier than it seems, and a practical checklist to break it.
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