Base64 to JSON
Decode Base64 into validated, pretty-printed JSON with indentation control.
Last updated: October 12, 2026
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Inspect Base64-encoded JWT payloads, webhook bodies, or config blobs as readable, validated JSON instead of guessing at raw strings.
All processing happens locally in your browser. Large files are handled in memory and never uploaded to any server.
Base64 to JSON
Turn Base64 back into readable JSON with our Base64 to JSON decoder. Paste any Base64 payload, including URL-safe alphabets with missing padding, and get back validated, pretty-printed JSON with switchable 2- or 4-space indentation. Failures are diagnosed precisely across three stages: invalid Base64, non-text bytes, or decoded text that is not JSON, with the offending opening characters shown. A success toast reports whether the root is an object or array plus its key or item count. Everything runs instantly and locally in your browser.
Why This Tool Exists
What makes this useful — and why I built it this way.
Readable Output: Minified payloads expanded and indented.
Exact Diagnosis: Know whether Base64, bytes, or JSON failed.
Tolerant Input: URL-safe and unpadded strings accepted.
Instant Summary: Root type and size reported on success.
Local Processing: Payloads never leave your browser.
When You'd Use This
Real situations where this tool saves the day.
JWT Inspection: Read encoded token payloads as formatted JSON.
Webhook Debugging: Decode Base64 request bodies into objects.
Config Recovery: Restore JSON blobs from encoded storage.
API Testing: Verify encoded fields decode to valid structures.
Learning: See how JSON maps to its Base64 form.
Using Base64 to JSON
It's straightforward — here's how it works.
Paste the Base64 string to inspect.
Choose 2- or 4-space indentation.
Click Process to decode and validate.
Copy the formatted JSON.
Questions People Ask
Honest answers about how this works.
What is the difference between this and Base64 to File?
Base64 to File rebuilds any file type for download with format detection. Base64 to JSON is JSON-specific: it validates the structure, pretty-prints it with indentation control, and explains exactly which stage failed when input is bad.
Does my payload leave the browser?
No. Decoding, validation, and formatting all run locally in your browser. Nothing is uploaded, logged, or stored.
Why does it say my text is not JSON?
The Base64 decoded fine, but the result is not JSON syntax — often plain text, HTML, or a truncated payload. The error shows the first 40 characters so you can see what it actually is.
Can it handle arrays and primitive values?
Yes. Objects, arrays, strings, numbers, booleans, and null all decode. The success message adapts, reporting key counts for objects and item counts for arrays.
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