Base64 Formatter Online
Format and normalize Base64 online: remove whitespace, fix/strip padding, wrap to 64/76 characters per line, and convert Base64URL ↔ Base64. Runs locally in your browser.
64 (PEM) and 76 (MIME).How to use
Paste your Base64, choose output options, then format.
- Paste text into Input (whitespace is allowed).
- Select Output mode (Standard, Base64URL, or Auto).
- Choose whether to Use padding (=) and whether to Wrap lines (line length should be a multiple of 4).
- Click Format (or Minify/Validate).
- Copy the result from Output.
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.
Continue your workflow
Browse related tools by task. Use the improved core tools for a consistent workspace with file import, downloads and clear validation errors.