Does Base64 encoding encrypt my data?

No. Base64 is an encoding scheme, not encryption. Anyone who receives a Base64 string can decode it instantly without a key. Do not use Base64 to hide sensitive data.

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

Standard Base64 uses + and / as its 62nd and 63rd characters. These have special meaning in URLs, so URL-safe Base64 replaces them with - and _ respectively. The output is otherwise identical and interchangeable if you handle the substitution correctly.

Does this verify the signature?

Yes — enter your HMAC secret or RSA/ECDSA public key in the Verify section. For HS* algorithms the secret is a plain text string; for RS*/ES* provide a PEM-formatted public key matching the private key that signed the token.

Is my token sent to a server?

The browser-side decoder never makes a network call — decoding is done entirely in JavaScript. The signature-verification call does send your token and key over HTTPS to a server-side endpoint, but neither is logged or stored.

Tool comparison

Base64 Encoder / Decoder vs JWT Decoder

Base64 Encoder / Decoder and JWT Decoder are both encoding tools. They serve related purposes but are optimised for different tasks — understanding the distinction helps you choose the right one for your workflow.

Bottom line

A JWT is a three-part Base64-URL-encoded structure — JWT Decoder understands that structure and validates the token format automatically. Use Base64 for arbitrary binary-to-text encoding; use JWT Decoder specifically when inspecting signed tokens.

What each tool does

Base64 Encoder / Decoder

Base64 is an encoding scheme that converts binary data — or any text — into a string of 64 ASCII characters (A–Z, a–z, 0–9, +, /). It is used wherever binary data must travel through a medium that only handles text: embedding images in HTML or CSS, encoding credentials in HTTP Authorization headers, storing binary payloads in JSON, and passing data through URLs. Base64 does not encrypt data; it only changes the representation. The URL-safe variant replaces + with - and / with _ so the result is safe to embed in URLs and filenames without percent-encoding.

Open Base64 Encoder / Decoder →

JWT Decoder

A JSON Web Token (JWT) is a compact, URL-safe string used to securely transmit claims between two parties. It consists of three base64url-encoded segments separated by dots: a header, a payload, and a signature. The header specifies the signing algorithm (such as HS256, RS256, or ES256). The payload contains claims — statements about an entity and additional metadata, such as a user ID (sub), an expiry time (exp), an issuer (iss), and any custom application-defined fields. The signature is computed over the header and payload using a secret or private key, allowing the recipient to verify that the token was issued by a trusted source and has not been modified. JWTs are the standard mechanism for stateless authentication in modern web applications: once issued, they travel with every API request (typically in the Authorization: Bearer header) and can be validated without a database lookup. This tool decodes the header and payload instantly without requiring a key, and can optionally verify the signature using your HMAC secret or RSA/ECDSA public key — all within your browser.

Open JWT Decoder →

Side-by-side comparison

Feature	Base64 Encoder / Decoder	JWT Decoder
Category	encoding	encoding
Primary purpose	Encode text or data to Base64, or decode Base64 back to plain text.	Decode and verify JSON Web Tokens — header, payload, claims, and signature.
Inputs	input, mode, charset	token, secret, algorithm
Outputs	output, valid, encoding, byte_length, error	header, payload, signature, valid_structure, verified

When to use each

Use Base64 Encoder / Decoder when…

How to encode a string to Base64

Convert plain text to a Base64 string for use in APIs, HTTP headers, or data URIs.

How to decode a Base64 string

Convert a Base64-encoded string back to its original plain text.

Use JWT Decoder when…

How to decode a JWT in your browser

Instantly inspect the header and payload of any JWT without installing software.

How to inspect an Auth0 JWT token

Read the claims inside an Auth0 access token or ID token to debug permissions and user data.

Frequently asked questions

Does Base64 encoding encrypt my data?: No. Base64 is an encoding scheme, not encryption. Anyone who receives a Base64 string can decode it instantly without a key. Do not use Base64 to hide sensitive data.
What is the difference between standard and URL-safe Base64?: Standard Base64 uses + and / as its 62nd and 63rd characters. These have special meaning in URLs, so URL-safe Base64 replaces them with - and _ respectively. The output is otherwise identical and interchangeable if you handle the substitution correctly.
Does this verify the signature?: Yes — enter your HMAC secret or RSA/ECDSA public key in the Verify section. For HS* algorithms the secret is a plain text string; for RS*/ES* provide a PEM-formatted public key matching the private key that signed the token.
Is my token sent to a server?: The browser-side decoder never makes a network call — decoding is done entirely in JavaScript. The signature-verification call does send your token and key over HTTPS to a server-side endpoint, but neither is logged or stored.