URL Encode & Decode Online
Safely encode special characters for URLs or decode percent-encoded text to inspect parameters—useful for OAuth callbacks, APIs, and debugging links.
What is URL encoding (percent-encoding)?
URL encoding replaces reserved or non-ASCII characters in URI components with percent-encoded bytes (for example, a space as %20)
so parsers do not confuse data with structural characters like ?, &, =, or #.
CompareStack’s encode/decode tool helps developers build safe query strings, debug OAuth callbacks, and fix broken deep links.
How to encode or decode on CompareStack
- Paste the text or URL segment into the input field.
- Choose Encode to produce a transport-safe string, or Decode to read percent-sequences as plain text.
- Copy the result into your application, test harness, or documentation.
- Encode once at the layer responsible for building URLs—avoid double-encoding already encoded values.
Encode once, decode once
Double-encoding turns %20 into %2520, breaking links and invalidating signatures. Decode at a single trusted
boundary (usually server-side) after transport. Remember that HTML forms using application/x-www-form-urlencoded treat
+ as space in body data, while path segments should use explicit %20.
Integration debugging scenarios
Payment gateways and OAuth providers return callbacks with strict byte requirements. If signature validation fails, compare encoded and decoded forms side by side and log the canonical string your verifier uses—not only the human-readable decoded view. Marketing teams encoding UTM parameters for non-ASCII campaign names should encode parameter values, not entire URLs blindly.
Security reminder
Encoding is not encryption. Secrets in query strings are visible in logs and browser history—use POST bodies or headers for sensitive tokens.
Related reading
- Base64 Encode / Decode
- JSON Formatter for API bodies alongside URL parameters
- URL Encoding Explained
URL encoding in real integrations
Encode user-supplied query values once at the boundary where URLs are built. Double-encoding is a common cause of broken links and invalid OAuth signatures.
Log the canonical encoded URL your verifier expects when debugging payment or auth callbacks.
Remember encoding is not encryption—never place secrets in query strings expecting safety from percent-encoding.
Tool FAQ
When should I encode a URL?
Encode query parameter values that contain spaces, ampersands, or non-ASCII characters before appending them to a URL.
Can encoding break OAuth signatures?
Yes. Signed URLs require exact byte sequences. Compare encoded and decoded forms carefully when debugging callbacks.
What is double-encoding?
Encoding an already-encoded string turns %20 into %2520 and breaks links. Encode once at the URL builder layer.
Is URL encoding the same as encryption?
No. Percent-encoding is reversible and not secret. Do not put passwords in query strings.