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Base64 Encoder & Decoder Online — Free Base64 Converter

Encode any text, file, or binary string to Base64, or decode a Base64 string back to plain text in seconds. The Base64 converter runs locally in your browser so nothing is uploaded — making it safe for credentials, API keys, and binary blobs you want to inspect during development.

Features

  • Text & file support

    Encode plain text strings or binary files. Decoded output is downloadable for binary payloads.

  • Standard & URL-safe

    Switch between standard Base64 and URL-safe Base64 (used in JWT, OAuth, and HTTP headers).

  • No size limit

    There is no server upload, so encoding speed depends only on your browser and machine.

  • Private by default

    Inputs are processed in-memory and never leave your device — safe for sensitive payloads.

How to Base64-encode a string online

Convert any text or binary input to or from Base64 in four steps.

  1. Choose the directionPick Encode (text → Base64) or Decode (Base64 → text) at the top of the tool.
  2. Paste your inputDrop your text into the input box, or upload a file for binary encoding.
  3. Inspect the resultThe output appears instantly. Switch between standard and URL-safe Base64 if needed.
  4. Copy or downloadUse the copy button for short strings, or download the result as a file for larger payloads.

Examples

Encode a plain string

Input
Hello, World!
Output
SGVsbG8sIFdvcmxkIQ==

Decode a Base64 string

Input
RGV2ZWxvcGVyIFRvb2xz
Output
Developer Tools

URL-safe Base64 (used in JWT)

Input
{"alg":"HS256","typ":"JWT"}
Output
eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9

URL-safe Base64 replaces `+` with `-`, `/` with `_`, and trims `=` padding, so the result is safe inside URLs and headers.

Frequently Asked Questions

What is Base64 encoding used for?
Base64 lets you transport binary data — images, certificates, signatures — through text-only channels like email, JSON, or HTTP headers. It is not encryption; anyone can decode it instantly.
Is Base64 encryption?
No. Base64 is encoding, not encryption. It hides nothing — any Base64 string can be decoded back to the original input in milliseconds. Use real encryption (AES, RSA) for confidentiality.
Why does Base64 add padding (`=`) at the end?
Base64 encodes three bytes into four characters. If the input is not a multiple of three bytes, `=` characters pad the output so its length is a multiple of four. URL-safe Base64 typically omits the padding.
What is the difference between standard and URL-safe Base64?
Standard Base64 uses `+` and `/`, which can break URLs. URL-safe Base64 substitutes `-` and `_` and is the variant used in JWT, OAuth state parameters, and other URL-bound payloads.
Can I encode files with this tool?
Yes. Upload a file and the tool reads it locally in your browser, then produces the Base64 representation. The file is never uploaded to a server.
How large can the input be?
There is no fixed limit because nothing is uploaded. Very large inputs (hundreds of MB) may slow the browser but will still work on modern machines.