URL Encoder / Decoder

The URL Encoder / Decoder handles percent-encoding in both directions with an explicit choice between the two JavaScript encoders people actually reach for. On the Encode tab, a radio group switches between encodeURIComponent — the strict mode that also encodes reserved characters like / : ? & = — and encodeURI, which preserves those characters so a full URI keeps its structure and only spaces and other unsafe glyphs become %xx sequences. This distinction is what prevents the classic mistake of double-encoding query strings or destroying a URL's slashes. The Decode tab runs decodeURIComponent on your input and rejects malformed sequences cleanly with a Malformed URI sequence toast explaining that the percent-encoding is invalid, rather than emitting broken text. A Load sample button drops in a realistic URL containing spaces, query parameters, and a subdomain so you can see the two modes differ on the same input, and a Clear button wipes both tabs. Outputs download as encoded-url.txt or decoded-url.txt. Whether you are building query strings for an API call, decoding a campaign link from analytics, or debugging why a redirect 404s, this is the tool for it.

1. 1

   Open the Encode tab and paste or type the text to percent-encode.

2. 2

   Choose the encoding mode: encodeURIComponent (strict) or encodeURI (full URI).

3. 3

   Read the encoded result instantly in the Encoded output box.

4. 4

   Switch to the Decode tab to reverse a percent-encoded string with decodeURIComponent.

5. 5

   Use Load sample and Clear as needed, and download results as encoded-url.txt or decoded-url.txt.

• Building safe query-string values for an API request in a client script.
• Decoding UTM or campaign parameters copied from an analytics URL.
• Preparing a value for a redirect or deep-link URL without breaking reserved characters.
• Double-checking why a URL 404s by decoding suspicious %xx sequences.
• Encoding JSON payloads that must travel inside a single query parameter.
• Converting a full URL into a component-safe string for nested links in emails.

• Match the mode to the job: encodeURIComponent for values that go inside parameters, encodeURI for whole URLs.
• Never encode an already-encoded string — double-encoding turns %20 into %2520 and breaks downstream parsers.
• Decode once at the boundary where you consume a value, not repeatedly at every layer of your stack.
• When embedding user input in a URL, encode each component separately rather than the assembled URL.
• If decoding fails with a malformed-sequence toast, check for stray % characters that are not valid hex pairs.
• Keep the two tabs' outputs separate — the Encode tab result does not feed the Decode tab automatically.

• Start with Load sample to see both modes produce different results from the same URL.
• Watch the character count hint under each input — a spike after encoding is normal for reserved characters.
• Use the strict mode when you are unsure: it never breaks a URL because it encodes everything.
• Decode any link you receive before pasting it into code — hidden percent sequences are a common source of 404s.