Universal Encoder Decoder
Universal Encoder Decoder is a free online tool for encoding and decoding text. Paste a string, pick one of 15 operations and get the result:
- Encode and decode: Base64, URL (percent-encoding), HTML entities, string ↔ hex, text ↔ binary
- Hash: MD5, SHA-1, SHA-256, SHA-512
- Shift: ROT13
It is a character encoder and decoder for everyday developer and SEO work: reading encoded URLs, checking redirect parameters, preparing strings for HTML or comparing hashes. Encoding is not encryption, and hashes cannot be decoded. For tokens, full URLs, domain names, JSON and images, use the dedicated tools below.
More free tools
These tools run in your browser: nothing you paste is uploaded.
JWT Decoder
Read a JSON Web Token's header and payload, with expiry dates, in your browser.
eyJhbGciOi… → {"alg":"HS256"}URL Parser
Split a URL into its parts and decode every query parameter, with encoding warnings.
?utm_source=x%20y → utm_source = x yPunycode Converter
Convert international domain names to xn-- form and back, one or many at a time.
bücher.de → xn--bcher-kva.deUnicode Escape
Turn text into \uXXXX, \u{…} or &#x…; escapes and decode them back.
café → caf\u00E9JSON Escape
Escape quotes, backslashes and line breaks for JSON strings, or unescape them.
He said "hi" → He said \"hi\"Image to Base64
Convert images to Base64 data URIs for HTML and CSS, or decode Base64 to an image.
logo.png → data:image/png;base64,iVBOR…
Guides
- URL encoding and Google indexing
How encoded URLs relate to crawling and indexing.
- %20 vs + in URLs: how spaces are encoded
Which form means a space where, and which functions produce each.
- Double URL encoding (%2520): causes and fixes
How to spot a string encoded twice and find the step that did it.
- How to decode a JWT without the secret
Reading token claims in code, and why that is not verification.
- Punycode (xn--) domains and SEO
How IDNs and their xn-- form fit together, and what Google says.
- Why Base64 makes data about 33% larger
The 3-bytes-to-4-characters math, padding and line breaks.
- HTML entities vs URL encoding in links
When to write & and when %26, and the bugs mixing them causes.
- MD5 vs SHA-256 for file checksums
Why SHA-256 is the default and when MD5 is still acceptable.
- URL-encode and decode in Google Sheets and Excel
ENCODEURL formulas plus decode functions for both apps.
- Base64 vs hex encoding
Size, readability and where each one is the convention.
- UTM parameter encoding mistakes
Eight encoding errors that split or lose campaign data.
Frequently asked questions
What can this universal decoder do?
It runs 15 operations: Base64 encode and decode, URL encode and decode, HTML encode and decode, string to hex and back, text to binary and back, MD5, SHA-1, SHA-256 and SHA-512 hashes, and ROT13. For JWTs, full URLs, Punycode domains, Unicode escapes, JSON strings and images, use the dedicated tools linked on this page.
Can it detect which encoding a string uses?
No, you choose the operation. Some formats are easy to recognize by eye: Base64 uses letters, digits, + and / and often ends in =, hex uses only 0-9 and a-f, URL encoding contains % followed by two hex digits, and a JWT is three Base64url parts separated by dots.
Can a hash such as MD5 or SHA-256 be decoded?
No. A hash is a one-way function: it produces a fixed-size fingerprint and the original text cannot be calculated from it. The tool can create hashes so you can compare them, but there is no decode operation for MD5, SHA-1, SHA-256 or SHA-512.
Is encoding the same as encryption?
No. Base64, URL encoding, HTML encoding, hex, binary and ROT13 change how text is written, and anyone can reverse them without a key. Use them to move data safely through systems, not to keep it secret.
Is my input sent to a server?
The main tool on this page sends your input to the site's server to compute the result and returns it to your browser. The six dedicated tools run entirely in your browser. Avoid entering passwords, live tokens or private keys in the main tool; see the privacy policy for details.