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Free Tools Galaxy
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100% free · no signupRuns in your browser

Base64 Decoder

Decode Base64 strings back to UTF-8 text.

Best for: Reading a data URI, inspecting the header or payload of a token, or recovering text that was Base64-encoded for transport.

Complete guide

Input

How it's calculated & sources
The Base64 Decoder 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.

Continue your journey

Where people usually head next.

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Complete guide

Quick answers

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

What is Base64 Decoder?
A Base64 decoder reverses Base64 encoding, turning the 64-character ASCII text back into the original bytes or text so you can read an encoded payload, data URI or token segment.
Why does Base64 Decoder matter?
Clean output means the input was valid Base64; an error usually means stray characters, wrong padding, or that the data was URL-safe Base64 fed to a standard decoder (or vice-versa).
How is Base64 Decoder calculated?
It reads the input four characters (24 bits) at a time, maps each character back to its 6-bit value, and reassembles the original three bytes, discarding any = padding. It runs entirely in your browser.
What are common base64 decoder mistakes?
Mixing standard and URL-safe alphabets — - and _ must be decoded with the URL-safe variant.
When should you use the Base64 Decoder?
Reading a data URI, inspecting the header or payload of a token, or recovering text that was Base64-encoded for transport.

What is the Base64 Decoder?

A Base64 decoder reverses Base64 encoding, turning the 64-character ASCII text back into the original bytes or text so you can read an encoded payload, data URI or token segment.

How the Base64 Decoder works

It reads the input four characters (24 bits) at a time, maps each character back to its 6-bit value, and reassembles the original three bytes, discarding any = padding. It runs entirely in your browser.

Worked example

'SGVsbG8=' → 'Hello'

Common mistakes to avoid

  • Mixing standard and URL-safe alphabets — - and _ must be decoded with the URL-safe variant.
  • Missing or extra = padding.
  • Assuming the decoded result is trustworthy — Base64 is encoding, not a signature.

Keywords: base64, decode.

Sources: RFC 4648 — Base64

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

Frequently asked questions

Is the Base64 Decoder 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 Decoder?+

Base64 Decoder uses the standard base64 decoder 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 Decoder runs entirely in your browser. Nothing is uploaded or saved to a server.

Can I use the Base64 Decoder 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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Reddit post
Title: I built/used this free base64 decoder — instant, no signup

Body: Decode Base64 strings back to UTF-8 text. Try it: https://freetoolsgalaxy.com/tools/base64-decoder
LinkedIn post
Base64 Decoder on Free Tools Galaxy — Decode Base64 strings back to UTF-8 text. https://freetoolsgalaxy.com/tools/base64-decoder
Medium intro
# Base64 Decoder — the free tool I keep coming back to

Decode Base64 strings back to UTF-8 text.

Try it: https://freetoolsgalaxy.com/tools/base64-decoder
Quora answer
The fastest way is to use a free in-browser base64 decoder: https://freetoolsgalaxy.com/tools/base64-decoder. Decode Base64 strings back to UTF-8 text.

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-decoder?embed=1" title="Base64 Decoder" 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-decoder" target="_blank" rel="noopener">Powered by Base64 Decoder 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-decoder?embed=1" title="Base64 Decoder" 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 Decoder — free online tool](https://freetoolsgalaxy.com/tools/base64-decoder)

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

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

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

I kept needing a quick pregnancy due date calculator 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 pregnancy due date use cases (pregnancy, due, date, baby) and links out to the formula + worked examples if you want to learn the math.

Link: https://freetoolsgalaxy.com/tools/pregnancy-due-date-calculator

Happy to take feedback — what's missing?
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