Base64 to JSON Converter
Decode Base64 strings to JSON and encode JSON to Base64 online. Free, runs in your browser.
Input
Output
What Is Base64 to JSON?
Base64 is an encoding scheme that represents binary data as ASCII text. When JSON data is Base64-encoded — common in APIs, JWTs, and data URLs — you need to decode it to read the original JSON. This tool decodes a Base64 string and pretty-prints the result as JSON. It also supports the reverse: encoding a JSON string into Base64.
Toggle between Decode (Base64 → JSON) and Encode (JSON → Base64) using the mode buttons. All processing runs in your browser — no data is sent to any server.
How to Use This Tool
Choose Mode
Select Decode to convert a Base64 string to JSON, or Encode to convert JSON to a Base64 string.
Paste Input
Paste your Base64 string or JSON into the left editor. Use Sample to load an example, or Upload to load from a file.
Copy or Download Result
The right panel updates automatically. Use Copy or Download to save the result.
Example
Decoding the Base64 string for {"name":"John","age":30}:
Base64 Input
JSON Output
Frequently Asked Questions
What happens if the Base64 does not decode to valid JSON?
The tool will show the raw decoded text. It tries to parse the result as JSON first; if that fails, it returns the plain decoded string.
Does this support URL-safe Base64?
The browser's atob() function used internally requires standard Base64. Replace - with + and _ with / before pasting URL-safe Base64.
Is my data sent to a server?
No. All processing happens locally in your browser.
Why do I get an error when encoding?
In Encode mode the input must be valid JSON. Fix any JSON syntax errors and try again.
Related Tools
The Base64 encoding scheme is defined in RFC 4648. See MDN: Base64 for browser support details.