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Base64 Decoder error
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// about this tool

Base64 Decoder Online

Updated 2026-08-19

Decode Base64 to plain text online, instantly and privately in your browser. Paste a Base64 string and SnapTools returns the original text as you type, with standard and URL-safe variants so the characters map back correctly. Nothing is uploaded; decoding runs locally, so it's safe for private payloads and tokens.

Base64 shows up everywhere data needs to travel as plain text — data URIs, API fields, auth headers, and config values. Because it's an encoding rather than encryption, decoding it simply reverses the transform and gives you the readable content back; it never proves anything was secure.

// how to use

  1. 1 Paste your Base64 string into the input panel on the left.
  2. 2 Choose the matching variant — standard or URL-safe — in the options.
  3. 3 Read the decoded text in the output panel on the right.
  4. 4 Use Copy or Download to save the decoded result.

// examples

Decode a standard string
Input
SGVsbG8=
Output
Hello
Decode URL-safe Base64
Input
c3ViamVjdHM_aWRzPTEmcGFnZT0y
Output
subjects?ids=1&page=2

// common uses

Reading values from data URIs Inspecting Base64 fields in API payloads Recovering encoded config or token values Decoding Basic Auth header contents

// faq

Is my Base64 sent to a server?
No. Decoding happens entirely in your browser, so nothing is uploaded and your input stays on your machine.
Does decoding Base64 reveal a secret?
Base64 is encoding, not encryption, so it provides no security — anyone can decode it. If a value was only Base64-encoded, decoding it exposes the original text, which is why secrets should never be stored that way.
What is the difference between standard and URL-safe decoding?
URL-safe Base64 uses "-" and "_" in place of "+" and "/". Pick the variant that matches how the string was encoded so the characters map back correctly.
Why do I get garbled output?
The input may be the wrong variant, have missing padding, or not be Base64 at all. Check that you've selected standard versus URL-safe correctly and that the whole string was copied.
How do I encode text in the first place?
Use the Base64 Encoder, which turns plain text into a Base64 string in standard, URL-safe, or MIME format.

// works with your data

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Use this via API

Get a free API key → 
curl -X POST https://thesnaptools.com/api/v1/tools/base64-decode \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"text":"SGVsbG8="}'