Base64 Encoder/Decoder

What is Base64 encoding?

Base64 is a way of representing binary or Unicode data using only 64 printable ASCII characters (A–Z, a–z, 0–9, +, /). It doesn't compress or encrypt anything — it just re-encodes bytes into a form that's guaranteed to survive text-only systems like HTTP headers, JSON fields, email, and URLs without corruption.

You'll run into Base64 constantly as a developer: HTTP Basic Auth sends username:password Base64-encoded in an Authorization header, data URIs embed images directly in HTML or CSS as Base64, and JWTs use a URL-safe variant for every segment of the token.

Standard Base64 vs. Base64URL

Standard Base64 uses + and / in its alphabet and pads the output to a multiple of 4 characters with trailing = signs. Both characters have special meaning in a URL, so pasting standard Base64 into a query string or path segment requires escaping.

Base64URL swaps + for - and / for _, and drops the padding entirely, producing a string that's safe to use directly in a URL, filename, or cookie. This tool's URL-safe toggle switches the output between the two, and decoding accepts either alphabet automatically so you never have to guess which one you're pasting.

Encoding and decoding text safely

Because encoding converts UTF-8 bytes rather than raw characters, this tool round-trips Unicode correctly — emoji, accented letters, and non-Latin scripts all decode back to exactly what you started with. Decoding validates the input's length and alphabet first, so a corrupted or truncated Base64 string is reported with a clear reason instead of producing garbled output.

JSON to Base64 — encode a JSON payload as Base64

To encode JSON to Base64, paste your JSON into the encoder — the tool converts the UTF-8 bytes of the JSON string into a Base64-encoded string. This is useful when you need to embed a JSON payload in a context that does not allow raw JSON: an HTTP header value, a URL query parameter, a cookie, or a string field inside another JSON document.

The output is standard Base64, or Base64URL (URL-safe, no padding) if you enable the toggle. To reverse it, switch to decode mode and paste the Base64 string — the decoder produces the original JSON text back. Everything runs in your browser, so JSON containing sensitive data stays private.

Base64 to JSON and JSON decoder

A JSON decoder reads an encoded representation of JSON and gives you back the original readable JSON text. The most common case: paste a Base64 string, switch to decode mode, and the tool decodes it back to JSON in one step.

JWT payloads, API tokens, and embedded config values are frequently Base64-encoded JSON. Decoding Base64 to JSON here lets you read the underlying data — the claims in a JWT header or payload, for example — without writing code. Both standard Base64 and the URL-safe Base64URL variant are accepted automatically so you never have to guess which encoding you are looking at.