Base64 Encoder & Decoder — What Is Base64 and When to Use It
Updated October 2026 · 4 min read
Quick start: Open the free Base64 Encoder — paste any text or data to encode or decode Base64 instantly in your browser.
Base64 is an encoding scheme that converts binary data — bytes — into a string of 64 printable ASCII characters. It does not encrypt; it simply represents arbitrary binary data in a text-safe format. Developers encounter it constantly in APIs, web tokens, email attachments and CSS data URIs.
Why Base64 Exists
Many protocols designed for text — email (SMTP), HTTP headers, JSON — cannot reliably transmit raw binary data. Null bytes, control characters and non-ASCII bytes cause corruption. Base64 solves this by representing any byte as one of 64 safe characters: A–Z, a–z, 0–9, + and /. The trade-off: Base64 is ~33% larger than the original binary.
Common Uses for Base64
| Use case | Example |
|---|---|
| Inline images in HTML/CSS | src="data:image/png;base64,iVBOR..." |
| JWT (JSON Web Tokens) | Header and payload sections are Base64URL-encoded |
| Basic HTTP authentication | Authorization: Basic dXNlcjpwYXNz |
| Email attachments (MIME) | File attachments encoded as Base64 in the email body |
| Storing binary in JSON/databases | Images, certificates, keys as text fields |
Base64 vs Base64URL
Standard Base64 uses + and /, which are special characters in URLs. Base64URL replaces them with - and _ — safe for use in URL query strings and HTTP headers without percent-encoding. JWTs use Base64URL. When decoding a JWT segment manually, use Base64URL decoding, not standard Base64.
Base64 Is Not Encryption
Base64 provides zero security — anyone can decode it instantly. Seeing Base64 in an API response or source code does not mean the data is protected. Never store passwords, secrets or sensitive data as Base64 and assume it is secure. For security, use proper encryption (AES) or hashing (bcrypt for passwords).
Encode or Decode Base64 Free
Supports standard Base64 and Base64URL. Runs entirely in your browser — nothing is sent to any server.
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