Base64 in HTTP Headers: Authorization, ETag, and Beyond
Many HTTP headers use Base64 encoding. This guide covers Authorization, WWW-Authenticate, ETag, and custom headers that rely on Base64 encoding.
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Tags: encoding, http, base64
Base64 in HTTP Headers: Authorization, ETag, and Beyond HTTP headers carry metadata about requests and responses. Most header values are plain text — content types, dates, lengths. But a surprising number of headers carry Base64-encoded data, either for transport compatibility, to avoid special character conflicts, or simply because the HTTP spec requires it. Knowing where Base64 appears in HTTP headers — and why — helps you debug network issues, build APIs correctly, and understand what your HTTP client is actually sending. The Authorization Header The most widely encountered Base64 in HTTP headers is in authentication. Two major schemes use it. Basic Authentication Covered in depth in the Basic Auth article, but worth recapping the format: The value after is . The colon in is a special…
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