Free tool
Base64 Encoder & Decoder
Encode text to Base64 or decode Base64 to text. Supports standard Base64 and URL-safe Base64URL encoding.
About Base64
Standard Base64: Uses A-Z, a-z, 0-9, +, / and = for padding.
Base64URL: URL-safe variant that uses - instead of + and _ instead of /. No padding.
Base64 encoding increases size by ~33% (3 bytes become 4 characters).
What is Base64?
Base64 is a binary-to-text encoding scheme that represents binary data in an ASCII string format. It is commonly used when you need to transmit binary data over systems designed to handle text.
Common use cases
- •Email attachments — MIME encoding uses Base64
- •Data URLs — Embedding images in HTML/CSS
- •API payloads — Encoding binary data in JSON
- •Basic authentication — HTTP Basic Auth headers
- •JWT tokens — Header and payload encoding
Base64 vs Base64URL
Standard Base64 uses + and / characters, which can cause issues in URLs. Base64URL replaces these with - and _, and omits padding, making it safe for URLs and filenames.
Size consideration
Base64 encoding increases data size by approximately 33%. Three bytes of binary data become four Base64 characters.
Building developer onboarding?
Skene generates onboarding checklists from your codebase.
