Why do I see '=' padding in Base64?

Padding '=' characters make the total length a multiple of 4, as required by the Base64 spec. Some URL-safe variants omit padding.

What is URL-safe Base64?

URL-safe Base64 replaces '+' with '-' and '/' with '_' and may remove padding. Many web APIs use this variant.

Does this tool send data to a server?

No. All encoding/decoding happens in your browser. SeaBeasties shows one small ad per page to keep tools free.

Base64 Tool

Encode or decode Base64 text in your browser. Heads up: Don’t paste secrets.

How to use

Quick steps (encode/decode in under a minute)

Select Encode or Decode.
Paste your text (Encode) or Base64 string (Decode) into Input.
Optionally enable URL-safe if your API uses - and _ instead of + and /.
Click Run. Copy the result with Copy Output.

Examples (copy/paste ready)

Plain text → Base64:

Input:  Hello, SeaBeasties! 🐋
Output (standard):  SGVsbG8sIFNlYUJlYXN0aWVzISDwn5Cw
Output (URL-safe):  SGVsbG8sIFNlYUJlYXN0aWVzISDwn5Cw

Base64 → Plain text:

Input:  eyJuYW1lIjoiS2xhdXMiLCJyb2xlIjoiTWFzY290In0=
Output: {"name":"Klaus","role":"Mascot"}

Header snippet (URL-safe decode):

Input:  eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9  (JWT header, Base64URL)
Output: {"typ":"JWT","alg":"HS256"}

Troubleshooting (common Base64 errors)

“Invalid length” or “Unexpected character”: Your string may be URL-safe. Try enabling URL-safe or replacing -→+, _→/, and re-adding = padding to a multiple of 4.
Garbled Unicode/emoji: Use this tool (it handles UTF-8 safely). Some older decoders break on multi-byte characters.
Line breaks/spaces: Remove whitespace before decoding (this tool does it automatically).
Security reminder: Base64 is not encryption—don’t paste secrets.

FAQ (short answers)

Is Base64 encryption? No—just encoding. Anyone can decode it.

Why padding =? To reach a length divisible by 4.

What is Base64URL? A variant using - and _ for URLs; padding may be omitted.

Where does processing happen? In your browser only.

Last updated: September 26, 2025. Maintained by Rogue Narwhal Ventures LLC.

About this Base64 Encode/Decode tool

This free Base64 tool lets you encode or decode text—handy for developers working with JSON, APIs, or binary-to-text conversions in URLs, headers, or local storage. Everything runs in your browser; nothing is uploaded, saved, or sent. Like all SeaBeasties tools, it’s lightweight, privacy-friendly, and supported by a single small ad per page.

Explore more utilities on the SeaBeasties Tools home.

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