Ithy

URL component encoder and decoder with form-plus mode

Encode a single URL component, such as one query value, rather than an entire URL. When decoding, choose whether a plus sign is literal or represents a space in form-style data.

Free to use, with no sign-in. Inputs and results stay in this page and are not sent with the form. Download a result before leaving; this tool does not save your work.

Enter text or data

Worked result

red & blue/green → red%20%26%20blue%2Fgreen.

  1. Encode reserved component characters such as & and /.
  2. Represent Unicode as UTF-8 percent-encoded bytes.
  3. Interpret plus signs according to the selected convention when decoding.

Encode a query value containing an ampersand

Suppose the intended value is red & blue/green. The ampersand belongs inside the value, not between separate query parameters.

Input: red & blue/green
Percent-encoded: red%20%26%20blue%2Fgreen
Form style: red+%26+blue%2Fgreen
A literal + encodes as %2B

Encoding the whole URL this way would also encode its structural delimiters. Assemble a URL from its components using a URL API rather than applying a component encoder indiscriminately.

Keep URL structure separate from its data

Percent encoding represents selected bytes using a percent sign and two hexadecimal digits. A component encoder protects characters that would otherwise carry structural meaning in a URL.

This tool uses encodeURIComponent semantics. Form mode additionally replaces encoded spaces with plus signs and reverses that rule on decoding. It is a component conversion helper, not a complete form serializer or a parser of a full URL.

Component space → %20
Literal plus → %2B
Form-mode space → +
Decoding is applied exactly once.

Input limits and common mistakes

Malformed percent escapes and invalid encoded UTF-8 are rejected. Input is limited to 200,000 characters. The tool does not open, navigate to or fetch any URL you enter.

Decoding once and decoding repeatedly can have different security implications. Output is text, not a safety verdict about a destination. Percent encoding is not HTML escaping, SQL parameterization or a replacement for validation in another context.

Questions about url encode and decode

Does + always mean a space?

No. It has that meaning in form-style query encoding. In a general URL component it may be a literal plus.

Why is %252F different from %2F?

One decoding pass turns %252F into %2F. Another pass turns that into /. This tool decodes exactly once.

Should I encode a full URL?

Use a URL builder for the full structure. This tool is intended for one component or value.

Sources and verification

These references explain the formulas or formats. The worked examples above were created for this tool and checked against independent calculations or format round trips. AI-assisted development does not imply a named human expert review.

Published 2026-10-23. Examples are illustrations, not measurements of a service or claims about search rankings.

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