Base64 to JSON
Decode a Base64 string, such as a token payload, and read the JSON it was hiding as clean, indented output.
Your data stays on your device
Input — Base64
- characters
- 0
- lines
- 0
- size
- 0 B
Output — JSON
- characters
- 0
- lines
- 0
- size
- 0 B
Options
About this tool
Base64 is everywhere JSON needs to travel through a text-only channel: JWT payloads, data URIs, signed cookies and configuration blobs. This tool decodes the Base64 back to text and then formats the JSON it contained.
Both the standard and URL-safe alphabets are accepted, and missing padding is tolerated, so a JWT payload segment pasted straight from a token decodes cleanly. If the decoded text is not valid JSON, the exact problem is reported.
How to use this tool
- Paste the Base64 string, for example the middle segment of a JWT.
- Choose an indentation style for the output.
- Press Decode to convert it to text and format the JSON.
- Copy or download the decoded document.
Key features
- Accepts standard and URL-safe Base64
- Tolerates missing padding
- Formats the decoded JSON with your chosen indentation
- UTF-8 correct decoding
- Reversible with JSON to Base64
Example
Input — Base64
eyJpZCI6NDIsIm9rIjp0cnVlfQ==Output — JSON
{
"id": 42,
"ok": true
}Good to know
- The decoded content must be JSON. To decode Base64 into plain text, use the Base64 Decode tool.
- A JWT has three dot-separated segments; paste only the payload segment here, not the whole token.
Frequently asked questions
Can I paste a whole JWT?
Paste only the payload segment — the part between the two dots. The header and signature are separate segments.
It fails to decode — why?
Either the string is not valid Base64, or the decoded text is not JSON. The error message says which.
Is anything uploaded?
No. Decoding and formatting run locally.
Your data stays on your device
Your data is processed locally in your browser and is not uploaded to our server. This page keeps working after you go offline, because there is nothing to send.