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Base64 Encode/Decode

Encode or decode Base64 strings.

Best for: Embedding small images or fonts inline as data URIs, putting binary in JSON, Basic-auth headers, and MIME email.

Complete guide

Input

How it's calculated & sources
The Base64 Encode/Decode uses the standard, deterministic formula, so the same inputs always produce the same result. It runs entirely in your browser, so your inputs are never uploaded. Last reviewed June 2026.

Free & no sign-up · runs entirely in your browser. Results are estimates for general information, not professional advice — verify important decisions with a qualified expert. Last reviewed June 2026.

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Complete guide

Quick answers

Short, sourced answers to the questions people (and AI assistants) ask most.

What is Base64 Encode/Decode?
This tool encodes text or binary data to Base64 and decodes it back — the 64-character ASCII representation used to carry data safely through text-only channels like URLs, JSON, email and data URIs.
Why does Base64 Encode/Decode matter?
Base64 is encoding, not encryption — the output is reversible by anyone, and is about 33% larger than the input.
How is Base64 Encode/Decode calculated?
To encode, it takes three bytes (24 bits) at a time, splits them into four 6-bit groups and maps each to a character from A-Z, a-z, 0-9, + and /, padding with = so the length is a multiple of four. Decoding reverses the process. Everything runs locally in your browser.
What are common base64 encode/decode mistakes?
Treating Base64 as a security measure — it hides nothing.
When should you use the Base64 Encode/Decode?
Embedding small images or fonts inline as data URIs, putting binary in JSON, Basic-auth headers, and MIME email.

What is the Base64 Encode/Decode?

This tool encodes text or binary data to Base64 and decodes it back — the 64-character ASCII representation used to carry data safely through text-only channels like URLs, JSON, email and data URIs.

How the Base64 Encode/Decode works

To encode, it takes three bytes (24 bits) at a time, splits them into four 6-bit groups and maps each to a character from A-Z, a-z, 0-9, + and /, padding with = so the length is a multiple of four. Decoding reverses the process. Everything runs locally in your browser.

Worked example

Encode: 'Hi' -> 'SGk=' Decode: 'SGVsbG8=' -> 'Hello'

Key terms

Padding:
Trailing = characters that pad the output to a multiple of four.
URL-safe Base64:
Uses - and _ instead of + and / so it is safe in URLs.

Common mistakes to avoid

  • Treating Base64 as a security measure — it hides nothing.
  • Using + and / inside a URL — use the URL-safe variant (- and _) there.
  • Encoding Unicode directly instead of converting to UTF-8 bytes first.

Keywords: base64, encode.

Sources: RFC 4648 — Base16/Base32/Base64

Reviewed by the Free Tools Galaxy editorial team · Updated June 2026 · Calculated privately in your browser.

Frequently asked questions

Is the Base64 Encode/Decode free to use?+

Yes. Every tool on Free Tools Galaxy is 100% free, runs in your browser and requires no signup.

How accurate is the Base64 Encode/Decode?+

Base64 Encode/Decode uses the standard base64 encode/decode formula in double-precision arithmetic, so the same inputs always produce the same result and you can verify any figure by hand. It is an educational estimate — real-world outcomes depend on your actual rates, rules and assumptions.

Do you store my inputs?+

No. The Base64 Encode/Decode runs entirely in your browser. Nothing is uploaded or saved to a server.

Can I use the Base64 Encode/Decode on mobile?+

Yes — the interface is fully responsive and works on phones, tablets and desktops.

What are common mistakes to avoid?+

The most frequent mistake is mixing units. Double-check your inputs use a single, consistent unit before clicking Calculate.

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🛠️Dev CleanupStep 2 / 4
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Share & publish

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Share-to-grow kit (Reddit, LinkedIn, Medium)
Reddit post
Title: I built/used this free base64 encode/decode — instant, no signup

Body: Encode or decode Base64 strings. Try it: https://freetoolsgalaxy.com/tools/base64
LinkedIn post
Base64 Encode/Decode on Free Tools Galaxy — Encode or decode Base64 strings. https://freetoolsgalaxy.com/tools/base64
Medium intro
# Base64 Encode/Decode — the free tool I keep coming back to

Encode or decode Base64 strings.

Try it: https://freetoolsgalaxy.com/tools/base64
Quora answer
The fastest way is to use a free in-browser base64 encode/decode: https://freetoolsgalaxy.com/tools/base64. Encode or decode Base64 strings.

Embed this tool anywhere

Free embed code for blogs, docs and dashboards. Every embed sends a backlink home — helping you and the galaxy grow together.

HTML iframe
Drop into any site — auto-resizes to its content height, theme-aware.
<iframe src="https://freetoolsgalaxy.com/tools/base64?embed=1" title="Base64 Encode/Decode" loading="lazy"
  style="width:100%;height:600px;border:0;border-radius:16px;background:#0b1020"
  allow="clipboard-write"></iframe>
<script>window.addEventListener("message",function(e){if(e.data&&e.data.type==="ftg-embed-height"){document.querySelectorAll("iframe").forEach(function(f){if(f.contentWindow===e.source){f.style.height=e.data.height+"px";}});}});</script>
<p><a href="https://freetoolsgalaxy.com/tools/base64" target="_blank" rel="noopener">Powered by Base64 Encode/Decode on Free Tools Galaxy</a></p>
Responsive wrapper
Aspect-locked container — good for blog post bodies.
<div style="position:relative;padding-bottom:75%;height:0;overflow:hidden;border-radius:16px">
  <iframe src="https://freetoolsgalaxy.com/tools/base64?embed=1" title="Base64 Encode/Decode" loading="lazy"
    style="position:absolute;inset:0;width:100%;height:100%;border:0" allow="clipboard-write"></iframe>
</div>
WordPress / Markdown
Paste in a custom-HTML block or markdown file.
[Base64 Encode/Decode — free online tool](https://freetoolsgalaxy.com/tools/base64)

<iframe src="https://freetoolsgalaxy.com/tools/base64?embed=1" width="100%" height="600" frameborder="0"></iframe>
Text link-back
Minimal credit link — best for sidebars and footers.
<a href="https://freetoolsgalaxy.com/tools/base64" target="_blank" rel="noopener">Try the free Base64 Encode/Decode</a>

Share-to-Grow Kit

Pre-written, ready-to-paste posts for every major channel. Help others discover this tool — and earn backlinks.

Title
I built a free word counter that works instantly in the browser — no signup, no ads in your face
Body
Hey r/[subreddit],

I kept needing a quick word counter and most options online were slow or behind paywalls, so I built one that:

• Runs 100% in your browser (your data never leaves your device)
• No signup, no email wall, no popups
• Loads in under a second on mobile

It covers the standard word counter use cases (count, words, characters) and links out to the formula + worked examples if you want to learn the math.

Link: https://freetoolsgalaxy.com/tools/word-counter

Happy to take feedback — what's missing?
Post to a relevant subreddit (e.g. r/InternetIsBeautiful, r/webdev, r/productivity). Avoid spammy subs.
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