Free Online Base64 Encoder

Encode images as Base64 data URIs to embed them directly inline in HTML img tags or CSS background-image properties. Eliminates extra HTTP requests for small icons and sprites — great for above-the-fold critical images.

HTTP Basic Auth requires credentials to be sent as 'username:password' encoded in Base64 in the Authorization header. Any server or API using Basic Auth requires this encoding for every authenticated request.

JSON Web Tokens use URL-safe Base64 (base64url) without padding to encode the header and payload sections. When building or testing JWTs, you need to Base64url-encode your JSON claims to construct the token parts.

REST APIs that accept JSON cannot natively transmit binary data (images, files, PDFs). Encoding binary content as Base64 allows it to be embedded as a string inside a JSON body — common in document processing, file upload, and messaging APIs.

All email attachments — documents, images, PDFs — are Base64-encoded in the MIME email format (RFC 2045). SMTP servers and email clients expect attachments as Base64 blocks with 76-character line wrapping. Essential for any email-sending application.

Kubernetes Secrets store sensitive data (passwords, tokens, TLS certificates, config files) as Base64-encoded values in YAML manifests. When creating secrets, you must Base64-encode the values before adding them to the manifest or use kubectl directly.

X.509 certificates are distributed in PEM format — a Base64-encoded representation of the DER binary wrapped with -----BEGIN CERTIFICATE----- headers. When deploying SSL certificates, creating CSRs, or working with public keys, you're always working with Base64.

CSS can embed SVG icons and custom web fonts as Base64-encoded data URIs, reducing network requests. SVG files can be encoded and used directly in CSS background-image, content, or mask-image properties, while fonts are embedded via @font-face src.