When should I use encodeURIComponent?

When encoding individual query parameter values. It encodes & and = which would break URL parsing.

When should I use encodeURI?

When encoding a full URL — it preserves the URL structure characters so the URL remains valid.

%20 represents a space in URLs. + is used in application/x-www-form-urlencoded (HTML form) encoding.

What's the difference between encodeURI and encodeURIComponent?

encodeURI encodes a full URL and preserves characters like :, /, ?, and & since they're structurally meaningful; encodeURIComponent encodes a single component (like a query value) and escapes those same characters because they'd otherwise be misread as URL structure.

Why did my URL break after encoding it twice?

Encoding an already-encoded string percent-encodes the % sign itself, turning "%20" into "%2520" — always decode first if you're unsure whether a string is already encoded.

Are all special characters encoded the same way across contexts?

Reserved-character conventions can differ — the classic application/x-www-form-urlencoded format used by HTML forms encodes spaces as +, while RFC 3986 percent-encoding used in URL paths uses %20.

Why does one emoji turn into a long string of % codes?

Percent-encoding operates on UTF-8 bytes, and characters outside basic ASCII (accented letters, emoji, CJK characters) take multiple bytes, each of which becomes its own %XX sequence.

tools / developer

URL Encoder / Decoder

Encode and decode URLs and URI components — supports percent encoding, encodeURI, and encodeURIComponent.

PLAIN TEXT

ENCODED URL

output appears here...

encodeURI vs encodeURIComponent

encodeURIComponent encodes everything except letters, digits, and - _ . ! ~ * ' ( ). Use this for query string values. encodeURI additionally preserves URL structure characters like / ? & = # :. Use this for full URLs.

FAQ

When should I use encodeURIComponent?: When encoding individual query parameter values. It encodes & and = which would break URL parsing.
When should I use encodeURI?: When encoding a full URL — it preserves the URL structure characters so the URL remains valid.
What is %20 vs +?: %20 represents a space in URLs. + is used in application/x-www-form-urlencoded (HTML form) encoding.

ABOUT THIS TOOL

Paste a URL or string to encode special characters into percent-encoded format, or decode an encoded URL back to readable text. URL encoding (percent-encoding) replaces characters outside the safe ASCII set — spaces, &, =, ?, non-Latin characters — with a % followed by their hex byte value, so a space becomes %20 and a colon becomes %3A, keeping URLs unambiguous for servers and browsers to parse. The tool distinguishes full encoding from component encoding, matching JavaScript's encodeURI versus encodeURIComponent behavior, since encoding a whole URL differs from encoding just a value going inside a query string. Handy when building query strings, sharing links with special characters, or debugging URL-related errors caused by unencoded input.

HOW TO USE

Choose Encode or Decode mode.
Paste the URL, query string, or plain text you want to convert.
If encoding a value meant for a single query parameter, use component encoding rather than full URL encoding so characters like & and = still get escaped.
Click convert and review the percent-encoded or decoded output.
Copy the result and drop it into your query string, API call, or link.
Decode any suspicious-looking %-prefixed string from a log or browser address bar to read it in plain text.

COMMON USE CASES

A developer building a search feature encodes a user's query text so spaces and special characters don't break the URL.
Someone sharing a link containing non-English characters or emoji encodes it so it pastes reliably into chat apps and emails.
A backend engineer decodes a redirect URL parameter from server logs to see exactly what value a client sent.
A developer debugging a broken API call notices an unencoded & inside a parameter value is truncating the request and fixes it by encoding.
A marketer building a UTM-tagged campaign URL encodes spaces and symbols in a campaign name so the link doesn't break when shared.

TIPS & COMMON MISTAKES

encodeURIComponent (component encoding) escapes more characters, including &, =, and ?, and is what you want for individual query parameter values; encodeURI (full encoding) leaves those characters alone because it assumes they're part of the URL structure.
Reserved characters like & and = have structural meaning in a URL — encoding them inside a value prevents them from being mistaken for a parameter separator.
Double-encoding is a common bug: encoding an already-encoded string turns "%20" into "%2520", so check whether your input is already percent-encoded before running it through again.
Unicode characters get encoded as multiple %XX sequences representing their UTF-8 bytes, so a single accented letter or emoji can expand into a longer percent-encoded string than you'd expect.