Basic Auth Header Generator

Basic Auth Header Generator is a free tool that creates the HTTP Authorization header for Basic authentication from a username and password, and decodes existing headers back into credentials. It works in your browser, so nothing you type is sent anywhere.

How to create a Basic auth header

1. Enter the username and password.
2. Copy the full header (Authorization: Basic …) or just its value.
3. Add it to your request, API client or configuration.

How Basic authentication works

The client joins the username and password with a colon, encodes the result withBase64, and sends it in the Authorization header. For example,Aladdin:open sesame becomes Basic QWxhZGRpbjpvcGVuIHNlc2FtZQ==. If credentials are missing, the server answers 401 Unauthorized with a WWW-Authenticate header.

Security

• Base64 is an encoding, not encryption; the decoder on this page reverses it instantly. Always use HTTPS.
• The credentials are sent with every request, so prefer tokens (such as OAuth or API keys) for public APIs.
• With curl, -u user:pass builds this header for you.

Troubleshooting a 401 response

• Wrong characters after decoding. Paste the header into the decoder above to check the exact username and password being sent, including stray spaces.
• Special characters in the password. Letters outside plain English, such as é, are encoded as UTF-8 here; a few older servers expect a different encoding and reject them.
• A colon in the username. The first colon separates username from password, so usernames can’t contain one.
• The header never arrives. Some proxies strip Authorization; check what the server received with the HTTP Headers Analyzer.

Frequently asked questions

Last updated 27 September 2026