Encoding Decoder: Detect and Decode Base64, URL, Hex, and HTML Entities Online

FAQ

How do I use the encoding detector?

Paste your encoded string into the input field and click "Detect Encoding." The tool analyzes the text and provides a list of potential encoding formats ranked by confidence. Once the results appear, click the "Decode" button next to any match to view the original content.

Which encoding types can this tool detect?

The detector recognizes seven common data formats:

• Base64 — A standard encoding frequently used in email attachments, JWT tokens, and data URIs.
• Base64URL — A URL-safe variation of Base64 that replaces the + and / characters with - and _.
• URL Encoding — Also known as percent-encoding, used to handle special characters (such as %20 for spaces) in query strings.
• HTML Entities — Named or numeric references like & or < used to display reserved characters in HTML.
• Hexadecimal — A sequence of hex digit pairs representing raw bytes.
• Base32 — An encoding format using letters A–Z and digits 2–7, often found in TOTP keys and DNS records.
• ROT13 — A simple substitution cipher that replaces a letter with the 13th letter after it in the alphabet.

How does the detection algorithm work?

Each supported format has a specific detector that evaluates the input's character set, length constraints, and structural patterns. For example, a valid Base64 string must consist of alphanumeric characters, +, /, and =, and its length must be a multiple of four. The tool assigns each potential match a confidence score from 0 to 100, displaying all results that meet the minimum threshold in descending order.

Can the tool detect multiple encodings at once?

Yes. It is common for a single string to match multiple encoding patterns. The tool lists every viable match along with its confidence score so you can determine the most likely format. For instance, a short Hexadecimal string like 48656c6c6f could technically be interpreted as Base64, but the Hex detector will report a significantly higher confidence score.

What if the decoded output looks wrong?

If the result is unintelligible, the input may have been encoded multiple times (for example, URL-encoded text wrapped inside a Base64 string). In this case, try decoding the output a second time. Additionally, verify that the entire string was pasted without truncation, as missing characters or broken padding can prevent successful decoding.

Is my input data stored or sent anywhere?

No. All detection and decoding logic is executed entirely within your browser's JavaScript engine. No data is transmitted over the network, saved to a database, or written to any server.