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Run Base64 examples in the interactive playground
New to Base64? Start with Fundamentals for guided examples and encoding patterns.

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Type Definition

Namespace providing standard (RFC 4648) and URL-safe base64 encoding/decoding. Built on Web APIs (btoa/atob) for maximum performance and compatibility. Zero-overhead design with tree-shakeable function exports. 
export type Base64String = string;
export type Base64UrlString = string;

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Web API Integration

JavaScript builtins available on all Uint8Array instances:
  • setFromBase64() - Populate from base64 string
  • toBase64() - Encode to base64 string
MDN Reference
toBase64() and setFromBase64() are available as of 2025 (Node.js 22+, Chrome 131+). Use Tevm’s Base64.encode() for broader compatibility.

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Quick Reference

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    Effect Schema

    import { Base64Schema, Base64UrlSchema } from '@tevm/voltaire/Base64/effect'

const bytes = new TextEncoder().encode('Hello')
const b64 = Base64Schema.from(bytes)
b64.toString() // 'SGVsbG8='

const b64url = Base64UrlSchema.from(bytes)
b64url.toString() // 'SGVsbG8'

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    API Methods

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    Encoding

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    Decoding

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    Validation

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    BrandedBase64

    Tree-shakeable functional API for minimal bundle size. View BrandedBase64 →

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    Types

    export type Base64String = string;
    Base64-encoded string using standard alphabet: A-Z, a-z, 0-9, +, /. Includes padding with = characters.

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    Usage Patterns

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    Encoding Binary Data

    const bytes = new Uint8Array([0x48, 0x65, 0x6c, 0x6c, 0x6f]);
const b64 = Base64.encode(bytes);
console.log(b64); // "SGVsbG8="

// Decode back to bytes
const decoded = Base64.decode(b64);
console.log(decoded); // Uint8Array([72, 101, 108, 108, 111])

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    Encoding Strings

    // UTF-8 string encoding
const message = "Hello, 世界!";
const encoded = Base64.encodeString(message);
const decoded = Base64.decodeToString(encoded);
console.log(decoded === message); // true

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    URL-Safe Encoding

    // For URLs, filenames, tokens
const data = new Uint8Array([255, 254, 253]);

// Standard encoding (with +, /, =)
const standard = Base64.encode(data);
// URL-safe encoding (with -, _, no padding)
const urlSafe = Base64.encodeUrlSafe(data);

// URL-safe can be used in query parameters
const url = `https://api.example.com?token=${urlSafe}`;

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    Safe Decoding with Validation

    function safeDecodeBase64(input: string): Uint8Array | null {
  if (!Base64.isValid(input)) {
    return null;
  }
  try {
    return Base64.decode(input);
  } catch {
    return null;
  }
}

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    Pre-allocating Buffers

    // Calculate buffer size before encoding
const dataSize = 1024;
const bufferSize = Base64.calcEncodedSize(dataSize);
console.log(bufferSize); // 1368 bytes needed

// Calculate decoded size
const encodedLength = 1368;
const decodedSize = Base64.calcDecodedSize(encodedLength);
console.log(decodedSize); // 1024 bytes maximum

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    Tree-Shaking

    Import only what you need for optimal bundle size: 
    // Import specific functions (tree-shakeable)
import { encode, decode, isValid } from 'tevm/BrandedBase64';

const data = new Uint8Array([72, 101, 108, 108, 111]);
const encoded = encode(data);
const decoded = decode(encoded);
const valid = isValid(encoded);

// Only these 3 functions included in bundle

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    Core Documentation

    • Hex - Hex string encoding and decoding
    • Keccak256 - Keccak256 hashing for data integrity
    • Uint - Unsigned integer utilities

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    Specification

    • RFC 4648 - Base64 encoding specification
      • Section 4: Standard base64 encoding
      • Section 5: URL-safe base64 encoding
    • MDN Web APIs - Browser base64 APIs