Convert Base64 to JSON

Decode a Base64-encoded string back into JSON. Reverses Base64 encoding to restore the original JSON object, array, or value for inspection and editing.

Input (Base64)
Output (JSON)

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What It Does

Decode a Base64-encoded string back into JSON. Reverses Base64 encoding to restore the original JSON object, array, or value for inspection and editing.

How It Works

Convert Base64 to JSON changes data from Base64 into Json. That is more than a cosmetic rewrite. Field layout, quoting, nesting, and even type representation can shift because the destination format has different rules and limits.

Conversion tools are constrained by the destination format. If the source can express nesting, comments, repeated keys, or mixed data types more richly than the target, the output may need to flatten or reinterpret part of the structure.

All processing happens in your browser, so your input stays on your device during the transformation.

Common Use Cases

  • Decode JWT payload sections to inspect claims
  • Restore JSON configuration stored as Base64 in environment variables
  • Decode API responses that transmit JSON data as Base64
  • Inspect Base64-encoded webhook payloads
  • Debug encoded JSON in database fields or message queues

How to Use

  1. Paste the Base64-encoded string into the input.
  2. Click Decode to convert it back to JSON.
  3. Review the decoded JSON output.
  4. The JSON is automatically formatted for readability.
  5. Copy the JSON for further use.

Features

  • Decodes standard Base64 and URL-safe Base64 variants
  • Validates the decoded output as valid JSON
  • Pretty-prints the resulting JSON with indentation
  • Shows error details if the Base64 isn't valid JSON
  • Handles large encoded payloads

Examples

Below is a representative input and output so you can see the transformation clearly.

Input
eyJuYW1lIjoiQWRhIiwic2NvcmUiOjl9
Output
{
  "name": "Ada",
  "score": 9
}

Edge Cases

  • Very large inputs can still stress the browser, especially when the tool is working across many JSON values. Split huge jobs into smaller batches if the page becomes sluggish.
  • Source values that look similar can map differently in the target format when data types are inferred, flattened, or serialized.
  • If the output looks wrong, compare the exact input and option values first, because Convert Base64 to JSON should be repeatable with the same settings.

Troubleshooting

  • Unexpected output often means the input is being split or interpreted at the wrong unit. For Convert Base64 to JSON, that unit is usually JSON values.
  • If a previous run looked different, check for hidden whitespace, changed separators, or a setting that was toggled accidentally.
  • If nothing changes, confirm that the input actually contains the pattern or structure this tool operates on.
  • If the page feels slow, reduce the input size and test a smaller sample first.

Tips

If decoding fails, check that the Base64 string is complete — partial strings from truncated logs or copy errors won't decode correctly.

Base64-Encoded JSON

Base64 encoding converts binary data (or text) into ASCII characters for safe transport. JSON is frequently Base64-encoded when embedded in URLs, HTTP headers, JWTs, environment variables, or message queues — contexts where special characters like braces and quotes would cause parsing problems. Decoding reverses this process.

JWT Inspection

JSON Web Tokens (JWTs) contain three Base64-URL-encoded sections separated by dots. The second section is the payload — a JSON object with claims like user ID, expiration time, and permissions. Paste just the payload section (between the first and second dots) to decode and inspect the claims without needing a JWT-specific tool.

Debugging Encoded Data

APIs and message queues sometimes encode JSON as Base64 for transport safety. When debugging, you'll encounter Base64 strings in logs, database fields, or configuration files that need decoding to understand their content. This tool decodes and formats the JSON in one step, saving you from manual decoding and formatting.

Frequently Asked Questions

What if the decoded output isn't valid JSON?

The tool will show the raw decoded text and indicate that it's not valid JSON. The original content may have been plain text, not JSON.

Does it handle URL-safe Base64?

Yes. Both standard Base64 (+/) and URL-safe Base64 (-_) variants are supported.

Can I decode JWT tokens?

Paste the payload section (second part, between the dots) of a JWT. The header and payload are Base64-URL-encoded JSON.

What if padding is missing?

Base64 strings should end with = or == for padding. The tool handles missing padding gracefully.

Is the output formatted?

Yes. The decoded JSON is pretty-printed with standard indentation for readability.

Can it handle nested JSON objects?

Yes. Any valid JSON structure — objects, arrays, nested combinations — will be decoded and displayed correctly.