Online Base64 & URL Encoder / Decoder
Base64 and URL encoding show up constantly in web development: embedding binary data in JSON or a data: URI, safely passing special characters in a URL query string, or reading an API token buried in an Authorization header. Switch between Encode and Decode and pick a format to convert instantly, entirely in your browser. It helps when a request parameter, token fragment, or pasted value contains Base64 or percent-encoded text that needs inspection.
How to encode or decode Base64 and URL strings online
Choose Encode or Decode, pick a format (Base64 or URL), paste your text into the input box, and click the action button. The result appears below with a one-click copy button — there's no size limit beyond what your browser can comfortably handle, and nothing is uploaded anywhere in either direction.
Base64 vs. URL encoding — when to use each
Base64 converts arbitrary binary data into a text-safe string using only letters, digits, +, /, and = for padding — common for embedding images or files inside JSON, a data: URI, or an HTTP Authorization header. URL encoding (percent-encoding) instead replaces characters that have special meaning in a URL — spaces, &, ?, #, and others — with a percent sign followed by a hex code, so they can be safely included in a query string or path.
Common use cases
- Decoding a JWT or Basic Auth token pulled from an HTTP header to inspect its contents
- Encoding a file or image into a Base64 data URI for inline embedding
- URL-encoding a value before building a query string by hand
- Decoding a percent-encoded parameter from a shared link to see its original value
How to use Encode / Decode for related tasks
Choose the encoding type, encode or decode the value, and remember that encoding changes representation but does not provide encryption.
Related tools: AES-256 Encrypt & Decrypt, Base64URL & Base32 Converter.
Frequently asked questions
What is Base64 encoding used for?
Base64 turns arbitrary binary data into a text-safe string using only letters, digits, +, /, and = — commonly used to embed images or files inside JSON, data: URIs, or email attachments, and to encode credentials or tokens in HTTP headers.
What is URL encoding (percent-encoding) used for?
URL encoding replaces characters that aren't safe in a URL (spaces, &, ?, #, and others) with a % followed by their hex code, so they can be safely included in a query string or path without being misinterpreted as part of the URL's structure.
Why did decoding my Base64 string fail?
The most common causes are an odd-length string, characters outside the Base64 alphabet, or a copy-paste that introduced extra whitespace or line breaks. This tool reports a decode error instead of silently returning garbage.
Is my data uploaded anywhere when I encode or decode it?
No — encoding and decoding use the browser's native TextEncoder, atob/btoa, and encodeURIComponent/decodeURIComponent functions entirely client-side. Nothing you type is ever sent to a server.
Is Base64 the same as encryption?
No. Base64 and URL encoding are reversible representations; use an encryption tool when confidentiality is required.