Base64 to JSON Decoder Online Free
Decode Base64 to pretty-printed JSON - URL-safe variant, sort keys, indent 2/4/tab/minified. Free, client-side, instant, offline, secure.
Decode Base64 and pretty-print as JSON. Handles JWT-style URL-safe variants, missing padding, UTF-8, and still shows the decoded text if it’s not valid JSON — so you always see what you got.
How to Use Base64 to JSON Decoder Online Free
- Paste your Base64 string into the input. For JWT payloads, grab just the middle section (
xxx.yyy.zzz→ copyyyy). The tool strips whitespace before decoding by default. - Pick your indent.
2 spacesmatches most style guides;4 spacesaligns with Python/PEP-8 taste;Tabplays with .editorconfig-set editors;Minifiedstrips all whitespace for one-line API payloads. - Toggle “Sort keys” if you want a diff-friendly output. Sorting recurses through nested objects; array element order is preserved (arrays are ordered by definition).
- Watch the stats line.
valid JSON · object · 5 keysmeans it parsed cleanly. If you seedecoded OK · not valid JSON, the Base64 was fine but the resulting text isn’t JSON - maybe you meant the Base64-to-ASCII decoder. - Check the banner on JSON errors. When parsing fails, the output starts with
// Decoded OK but JSON parse failed: <reason>and shows the raw decoded text below. The//comment line isn’t valid JSON - strip it if you copy the result. - Copy or download. Copy writes to clipboard; Download saves as
decoded-<timestamp>.jsonwithapplication/jsonMIME type. Keyboard shortcut:Ctrl+Enter/Cmd+Enterdecodes and copies in one step. - Fix errors. Base64 errors name the exact bad character and its position. JSON errors include the offset from the JS engine - e.g. “Unexpected token y in JSON at position 12”.
Frequently Asked Questions
What is Base64 to JSON used for?
It recovers JSON payloads that were Base64 encoded for transmission, such as JWT claims, API responses inside text fields, or config data embedded in URLs. The tool decodes and pretty-prints in one step.
What indent options are available?
You can choose 2 spaces, 4 spaces, or tab indentation. 2 spaces is the default and most common in web development.
What does sort keys do?
Sort keys reorganizes all object keys alphabetically at every nesting level. This is useful for diffing JSON or producing canonical output for hashing.
Can it handle URL-safe Base64?
Yes. Both standard and URL-safe Base64 variants are detected automatically. Missing padding is also fixed before decoding.
Is my JSON secure?
Yes. Decoding runs entirely in your browser. Your Base64 string and the resulting JSON stay on your device.
Do you log decoded content?
No. The tool is fully client-side. Nothing is stored or transmitted.
Is this free?
Yes, no sign-up and no limits.
What if the decoded text is not valid JSON?
The tool shows the raw decoded text and a clear JSON parse error pointing to the line and column where the problem starts.
Can I copy or download the formatted JSON?
Yes. Both Copy and Download .json buttons are provided after a successful conversion.
Which browsers are supported?
All modern browsers including Chrome, Firefox, Safari, and Edge.