Simple online tools for developers, networking, text and conversions.

Developer Tools

Base64 Decoder

Decode Base64 instantly to recover readable text from API data, tokens, headers, and test payloads.

Tool

Use this free Base64 Decoder to convert Base64-encoded text back into readable plain text instantly. It is useful when inspecting API payloads, debugging encoded headers, checking copied tokens, reading encoded JSON strings, and verifying transmitted text during development or testing. Paste a Base64 value to decode it quickly and confirm what the encoded data actually contains.

About this tool

Use this free Base64 Decoder to convert Base64-encoded text back into readable plain text instantly. It is useful when inspecting API payloads, debugging encoded headers, checking copied tokens, reading encoded JSON strings, and verifying transmitted text during development or testing. Paste a Base64 value to decode it quickly and confirm what the encoded data actually contains.

Use base64 decoder when you need a fast browser-based result without extra setup. It works well for quick checks, one-off tasks, and routine formatting or calculation work.

What Base64 Decoder is good for

Privacy and browser-side use

If this tool runs fully in the browser, your input stays on the client side instead of being uploaded to a server. That makes it useful for quick decoding of copied API values, headers, config strings, payload fragments, and test data when you want a fast local result.

When to use Base64 Decoder

Base64 Decoder vs related tools

Base64 Decoder vs Base64 Encoder

Base64 Decoder turns encoded text back into readable text. Base64 Encoder does the reverse and creates Base64 from plain text. If your input already looks encoded, decode it first before trying anything else.

Base64 Decoder vs JWT Decoder

Base64 Decoder is for standard Base64 strings. JWT Decoder is better for JWT tokens because JWT parts use Base64 URL and have a specific token structure. If your value contains dot-separated token parts, the JWT tool is usually the right place to inspect it.

Helpful next steps

If you want to convert readable text back into Base64, use Base64 Encoder. If your value is URL-encoded rather than Base64, try URL Decoder. If the decoded result is JSON text, you may want to inspect it with JSON Validator or JSON Formatter.

Common mistakes when decoding Base64

Learn more

Why use this tool

How to use

  1. Paste the Base64 string into the input box
  2. Click Run Tool to decode the value
  3. Review the decoded text in the output area
  4. If decoding fails, check for invalid characters, truncation, or the wrong Base64 variant
  5. Copy the decoded result or compare it with the original expected text

Examples

Example

Input

SGVsbG8=

Output

Hello

A standard Base64 value decodes back into plain text.

Example

Input

aGVsbG8gd29ybGQ=

Output

hello world

Useful when checking encoded strings copied from scripts or tools.

Example

Input

eyJuYW1lIjoiSm9obiIsInJvbGUiOiJhZG1pbiJ9

Output

{"name":"John","role":"admin"}

Helpful when a system stores or transfers JSON as Base64 text.

Example

Input

dXNlcjpwYXNzd29yZDEyMw==

Output

user:password123

Useful for understanding what was encoded before it was placed into a header or test value.

Example

Input

aHR0cHM6Ly9leGFtcGxlLmNvbT9hPTEmYj0y

Output

https://example.com?a=1&b=2

Helpful when debugging encoded links or stored URL strings.

Example

Input

bGluZSBvbmUKbGluZSB0d28=

Output

line one
line two

Line breaks are preserved when the value is decoded.

Example

Input

0J/RgNC40LLQtdGC

Output

Привет

Useful for verifying non-English or Unicode strings inside encoded payloads.

Example

Input

SGVsbG8***

Output

Invalid Base64 input

Decoding fails when the pasted value contains invalid characters or broken formatting.

Common errors

Pasting a value that is not valid Base64

Fix: Check for invalid characters, broken padding, or copied text that is not actually Base64.

Trying to decode Base64 URL with the standard decoder

Fix: Use the Base64 URL decoder if the value uses URL-safe characters like - and _.

The string was truncated when copied

Fix: Copy the full encoded value, including any trailing padding characters if present.

Hidden spaces or line breaks were added to the input

Fix: Trim the input and remove accidental whitespace before decoding.

Assuming decoded output will always be readable text

Fix: Some Base64 values represent binary or structured data, so the result may not be human-readable text.

FAQ

What does a Base64 decoder do?

A Base64 decoder converts Base64-encoded text back into its original plain text or readable string form.

What is the difference between Base64 Decoder and Base64 Encoder?

Base64 Decoder turns encoded text back into readable text, while Base64 Encoder converts readable text into Base64.

Why does decoding fail?

The most common reasons are invalid characters, missing padding, truncated input, hidden whitespace, or using the wrong Base64 variant.

Can I decode JSON with this tool?

Yes. If a JSON string was encoded as Base64, this tool can decode it back into readable JSON text.

Can I decode Unicode or non-English text?

Yes. This is useful when checking encoded international text, symbols, or non-Latin strings.

What is the difference between standard Base64 and Base64 URL?

Standard Base64 uses characters like + and /, while Base64 URL uses URL-safe replacements such as - and _. They are similar but not always interchangeable.

Why does my decoded result look strange?

The encoded value may represent binary data, compressed data, or structured content instead of normal plain text.

Can I use this tool to inspect API payloads and headers?

Yes. That is one of the most practical uses for a Base64 decoder during development and debugging.

Should I decode a JWT with this page?

Not usually. JWT payloads use Base64 URL rather than standard Base64, so a JWT-specific tool is usually better.

When should I use Base64 Encoder after decoding?

Use the encoder when you want to confirm a round-trip conversion or recreate a valid Base64 value from readable text.

Use cases

Related tools