Does non-ASCII text survive Base64 encoding?

Yes. The browser's built-in btoa only accepts Latin-1, so non-ASCII input would normally throw. This tool converts to UTF-8 bytes first and decodes back to UTF-8, so text and emoji round-trip correctly.

When should I use URL-safe Base64?

The +, / and = characters in standard Base64 have other meanings in URLs and filenames. URL-safe output replaces them with - and _ and drops the trailing padding, so the value can go straight into an address. JWT uses this form.

Does it verify the JWT signature?

No. Verification needs the secret key, and pasting a secret key into a web page is not safe. This tool shows what the token contains and when it expires. Verify on your server.

encodeURIComponent or encodeURI?

This tool uses encodeURIComponent, which is what you want for a single value such as one query-string parameter — it encodes :, / and ? too. encodeURI, used for a whole address, leaves those separators alone.

Is anything I paste sent to a server?

No. Every conversion happens inside your browser and nothing is transmitted.

Base64 Encode & Decode - URL Encoder and JWT Decoder Online

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Developer Tools

URL-safe (+/ → -_, no padding)

Input

Encoding and decoding features

Base64 Encode/Decode — convert text to Base64 and back. Non-ASCII text and emoji are converted through UTF-8 bytes, so nothing breaks. URL-safe output (+/ → -_, padding removed) is supported for use in URLs and filenames. URL Encode/Decode — percent-encode a value for a query string, or turn an encoded address back into something readable. JWT Decoder — expands the header and payload and shows the issued-at (iat) and expiry (exp) claims as human-readable times. Whatever you paste stays in your browser.

How to use

1. Pick Base64, URL or JWT at the top. 2. For Base64 and URL, choose the direction — encode or decode. 3. Paste your input; the result is computed as you type, with no convert button. 4. Use the copy button next to the result.

When to use it

• See what a Base64 blob in an API response actually contains • Build a Basic auth header value • Encode or decode query strings with non-ASCII characters • Check which claims a login token carries and when it expires • Work with the Base64 part of an image data URL

Frequently Asked Questions

Q. Does non-ASCII text survive Base64 encoding?: A. Yes. The browser's built-in btoa only accepts Latin-1, so non-ASCII input would normally throw. This tool converts to UTF-8 bytes first and decodes back to UTF-8, so text and emoji round-trip correctly.
Q. When should I use URL-safe Base64?: A. The +, / and = characters in standard Base64 have other meanings in URLs and filenames. URL-safe output replaces them with - and _ and drops the trailing padding, so the value can go straight into an address. JWT uses this form.
Q. Does it verify the JWT signature?: A. No. Verification needs the secret key, and pasting a secret key into a web page is not safe. This tool shows what the token contains and when it expires. Verify on your server.
Q. encodeURIComponent or encodeURI?: A. This tool uses encodeURIComponent, which is what you want for a single value such as one query-string parameter — it encodes :, / and ? too. encodeURI, used for a whole address, leaves those separators alone.
Q. Is anything I paste sent to a server?: A. No. Every conversion happens inside your browser and nothing is transmitted.