What causes a “malformed URI sequence” error?

Either a % that is not followed by two hexadecimal digits, or well-formed escapes whose bytes are not valid UTF-8. The first is usually a literal percent sign that should have been written %25, and the error names the line and column so you can see which one. The second normally means the text was encoded in a different character set, or that a multi-byte sequence was cut in half.

URL Encoder

No upload · runs in your browser

Scope

Spaces

Text in

0 characters

Result

Runs entirely in your browser, nothing is uploaded.

How it works

URL Encoder and Decoder for Percent-Encoding

Percent-encode or decode text for URLs, switch between component and whole-URL escaping, or paste a full link to split its query string into readable parameters.

What this does

encodeURIComponent for a value going inside one field, encodeURI for a whole address
Spaces written as %20 or as +, matching HTML form encoding
Query parser that lists one decoded row per parameter and numbers the repeated keys
A failed decode names the line and column of the offending %

FAQ

Component escaping covers every reserved character, / ? & = # and : included, because the text is going inside a single field of a URL. Full-URI escaping leaves those structural characters alone so an entire address stays usable. Use component for a query value, full URI to repair spaces and accents in a link you already have.

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