What is the difference between standard and URL-safe Base64?

Standard Base64 uses + and / and adds = padding. URL-safe Base64 uses - and _ instead and strips the = padding. This decoder auto-detects which variant you have — if the input contains - or _ it treats it as URL-safe and restores the standard characters before decoding.

Decode Base64 to JSON — Auto-Detect URL-Safe Format

Q: How do I decode Base64 to JSON?

Paste your Base64 string into the decoder above and click Decode. The tool auto-detects standard and URL-safe Base64. In JavaScript: JSON.parse(atob(base64String)). In Python: json.loads(base64.b64decode(s)). In Node.js: JSON.parse(Buffer.from(s, 'base64').toString()). Select the Code Snippets mode for complete code.

Q: How do I decode a JWT payload?

A JWT has three parts separated by dots: header.payload.signature. Copy the middle part (the payload) and paste it into this decoder. The payload is Base64url-encoded JSON containing the token claims. The tool automatically handles URL-safe Base64 (no + or / characters, no = padding).

Base64 to JSON Decoder 100% client-side

Base64 input

Encoding

JSON output

JSON ready

Decoding JWT payloads

JWT tokens are three Base64url-encoded parts separated by dots.

A JWT looks like header.payload.signature. Copy the middle section (between the first and second dot) and paste it here to see the claims. The header (first section) is also Base64url JSON — paste it to see the algorithm. The signature (third section) is not JSON and cannot be decoded here.

When do you need to decode Base64 to JSON?

Debugging JWT tokens

JWTs are used for authentication in almost every modern web application. When debugging auth issues, decoding the payload reveals the claims — user ID, roles, expiry time and custom data. Paste the middle section of any JWT to inspect it without any external tool.

Kubernetes secrets

Kubernetes stores secret values as Base64-encoded strings in YAML manifests. To inspect the actual content of a secret: kubectl get secret mysecret -o jsonpath='{.data.config}' returns Base64. Paste it here to read the JSON configuration inside.

Webhook payloads

Some webhook providers Base64-encode the event payload in the request body or header for safe transport. Decode the value here to inspect the event structure before writing your webhook handler — no local server required.

URL parameters

APIs and deep-link schemes often pass complex state as Base64-encoded JSON in URL query parameters. Decode any suspicious URL parameter here to understand what data is being passed — useful for debugging, reverse engineering and API testing.

Base64 decoded in your
browser. No upload.

The entire decoding runs in JavaScript using the browser's native atob() function. Your data never leaves your browser — no server, no logs.

Auto-detection inspects the input for URL-safe characters (- and _) and missing padding, restores them before decoding. Data URIs (data:application/json;base64,…) are stripped automatically.

Auto-detect encoding

Detects standard vs URL-safe Base64 from the characters — no need to specify which variant you have.

Data URI support

Strips the data:application/json;base64, prefix automatically before decoding.

JWT payload decoder

JWT payloads are Base64url — auto-detection handles them correctly without manual configuration.

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Frequently asked questions

How do I decode Base64 to JSON in JavaScript?

JSON.parse(atob(base64String)) — but this fails for non-ASCII characters. Use JSON.parse(decodeURIComponent(escape(atob(b64)))) for full Unicode support. For URL-safe Base64: restore + and / first, add padding, then atob(). Select the Code Snippets mode for the complete pattern.

How do I decode a JWT payload?

Split the JWT on dots and take the second part: const payload = jwt.split('.')[1]. Then paste it into the decoder above, or in code: JSON.parse(atob(payload.replace(/-/g, '+').replace(/_/g, '/'))). The payload contains the claims — sub, iat, exp and any custom fields.

How do I decode Base64 to JSON in Python?

import base64, json; data = json.loads(base64.b64decode(s)). For URL-safe: json.loads(base64.urlsafe_b64decode(s + '=='[:len(s) % 4])). The padding trick handles missing = characters from URL-safe encoded strings.

Is the Base64 to JSON decoder free?

Yes, completely free. No file size limits, no account required. JSONshift is funded by non-intrusive display advertising.

Decode Base64 to JSONAuto-detect URL-safe.Pretty-printed output.

Base64 decoded in yourbrowser. No upload.

Decode Base64 to JSON
Auto-detect URL-safe.
Pretty-printed output.

Base64 decoded in your
browser. No upload.