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Base64 Decode Online

Paste a Base64 string, see the decoded text. Works with standard and URL-safe Base64.

Base64 Encoder

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How to Base64 Decode Online

  1. 1

    Paste the Base64 string

    Copy the encoded string from an API response, email header, JWT token, or data URI and paste it in.

  2. 2

    Decode

    Click decode. The tool reverses the Base64 encoding and shows the original text content.

  3. 3

    Read and copy the output

    View the decoded text. If the original was JSON, you might want to run it through a JSON formatter next.

When You Need to Read What's Inside

Base64 strings show up everywhere in development. JWT tokens have three Base64-encoded sections separated by dots. Email headers encode non-ASCII characters in Base64. API error responses sometimes return Base64-encoded details. Data URIs in CSS embed entire files as Base64 strings.

Decoding reveals what's actually in there. A JWT's middle section decodes to a JSON object with user claims. An email header decodes to the actual subject line in its original language. That mysterious string in your API response turns out to be a JSON error object someone encoded for transport.

This decoder handles both standard Base64 (with + and /) and URL-safe Base64 (with - and _). It also tolerates missing padding characters, which some implementations omit.

Frequently Asked Questions

Can I decode a JWT token with this?

Partially. A JWT has three parts separated by dots: header, payload, and signature. You can decode the header and payload sections individually — they're Base64URL-encoded JSON. The signature section is binary data and won't produce readable text.

What if the decoded output is garbled?

The original data might be binary (an image, a compressed file, encrypted data) rather than text. Base64 encodes any binary data, not just text. If you're expecting text and getting garbage, the source data isn't a text string.

Is URL-safe Base64 different from standard Base64?

Slightly. URL-safe Base64 replaces + with - and / with _ to avoid conflicts with URL syntax. The padding character = is sometimes omitted. This decoder handles both variants automatically.