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Base64 Formatter Online

Clean up messy Base64 fast: strip whitespace, normalize alphabet (Base64URL ↔ standard), optionally add/strip = padding, and wrap into fixed-width lines for PEM/email/logs. Everything runs locally in your browser.

Category: Developer · URL: /tools/base64-formatter-online.html
Tip: common wraps are 64 (PEM) and 76 (MIME).
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Privacy: runs locally in your browser. No uploads, no tracking scripts.

How to use

Paste your Base64, choose output options, then format.

  1. Paste text into Input (whitespace is allowed).
  2. Select Output mode (Standard, Base64URL, or Auto).
  3. Choose whether to Use padding (=) and whether to Wrap lines (line length should be a multiple of 4).
  4. Click Format (or Minify/Validate).
  5. Copy the result from Output.
Keywords this page targets (natural cluster): base64 formatter online, format base64 with line breaks, wrap base64 64 characters, wrap base64 76 characters, pretty print base64, base64 normalize whitespace, remove spaces from base64, base64url to base64 converter, base64 to base64url converter, fix base64 padding, strip base64 padding, validate base64 format, base64 line wrap tool, pem base64 formatter, mail base64 76 chars, base64 tidy tool, base64 minify, base64 format checker
Secondary intents covered: Remove whitespace/newlines from a copied Base64 string, Wrap Base64 output to a specific line length (64/76/custom), Convert Base64URL characters (- and _) to standard Base64 (+ and /) and back, Add missing padding or strip padding depending on target usage, Validate whether a string is valid Base64/Base64URL (with strict rules), Prepare Base64 for PEM blocks, email transport, or log readability, Quickly copy the formatted result to clipboard, Troubleshoot “invalid character/incorrect padding” Base64 errors

FAQ

What does a Base64 formatter do?

It removes whitespace, normalizes Base64/Base64URL characters, optionally fixes/strips padding, and can wrap the string into fixed-width lines.

Why should line length be a multiple of 4?

Base64 encodes data in 4-character blocks, so wrapping at multiples of 4 keeps blocks intact and avoids breaking decoders that expect aligned chunks.

What’s the difference between Base64 and Base64URL?

Base64 uses + and /, while Base64URL uses - and _ to be URL-safe; padding (=) is often omitted in Base64URL.

Should I keep or remove the '=' padding?

Keep padding for strict Base64 decoders and many specs; remove it for URL tokens or systems that expect unpadded Base64URL.

What does “Strict” validation mean here?

Strict mode enforces correct characters, padding placement, and (after normalization) a length that’s a multiple of 4.

Is my data uploaded to a server?

No. The formatter runs in your browser and does not make network requests.

Can this tool fix corrupted Base64?

It can fix common formatting issues (whitespace, wrong alphabet, missing/extra padding), but it can’t recover data if characters are actually wrong or missing.