A query value containing a space, an ampersand, or a slash silently truncates a link or splits into a parameter you never meant to send.
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URL Encoder Decoder
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Free · API · MCPToolYour platform
Use URL Encoder Decoder three ways
The free URL Encoder Decoder on this page works in your browser. The same workflow is available via REST API for apps and via MCP for Cursor, Claude, and other agents — one API key, one plan, one quota. This tool is part of the developer-apis module under Developer Tools.
- Free in browserUse URL Encoder Decoder here — no account required.
- REST APICall from your server with
X-Api-Key. - MCP for agentsConnect Cursor or Claude to ToolYour MCP with the same key.
- 1. Get an API keySign in and open Dashboard → API Keys (works for REST and MCP).
- 2. Call or connectUse the REST API from your server, or paste the MCP URL into your agent config.
- 3. Same qualityOutput matches the free web tool across all three surfaces.
What is URL Encoder Decoder?
A query value containing a space, an ampersand, or a slash silently truncates a link or splits into a parameter you never meant to send. This URL encoder decoder applies component-level percent-encoding — the same semantics as JavaScript's encodeURIComponent — so reserved characters travel as data rather than as structure.
Decoding reverses it, and additionally treats a plus sign as a space so form-encoded strings from logs decode the way a server would read them. Malformed percent sequences fail with a clear error instead of returning half-decoded text. The important limit is in the name: this encodes components. Running a whole URL through it escapes the colon and slashes of the scheme too, which is almost never what you want. When the value you are encoding is itself binary or opaque, Base64 Encoder Decoder is the right neighbour.
Browser use is free and needs no signup. The same job runs over REST at POST https://api.toolyour.com/api/v1/developer-apis/url-encoder-decoder and over MCP at https://api.toolyour.com/mcp — one API key, one shared monthly credit pool, 1 credit per successful call.
What are common questions about URL Encoder Decoder?
Should I encode the whole URL or just the value?
Just the value. Encoding a full URL escapes the scheme separator and slashes, producing a string that no client will resolve.
How is a plus sign handled?
On decode it is treated as a space, matching form-encoded bodies and query strings. On encode, spaces become %20.
What happens with a broken percent sequence?
Decoding fails with an error rather than returning partially decoded text, so you never act on a half-readable value.
What are the key features of URL Encoder Decoder?
Component-level semantics
Matches encodeURIComponent and decodeURIComponent, so browser and server behaviour agree.
Form-string friendly decoding
Plus signs decode to spaces, which is what logged form bodies actually mean.
Clear failure on bad input
Malformed escape sequences error out instead of silently mangling the value.
How do you use URL Encoder Decoder?
Isolate the value
Take the single parameter or path segment, not the entire URL.
Encode or decode
Encode before building the link; decode when reading one out of a log.
Reassemble the URL
Paste the safe value back into the query string or route.
Why links break without percent-encoding
A URL reserves a handful of characters for structure:
? starts the query, & separates parameters, # starts the fragment, and / separates path segments. When a value contains one of those characters as data, the parser has no way to tell the difference and reads it as structure instead.
The visible symptoms are familiar. A search term with an ampersand arrives truncated at the ampersand. A redirect target containing its own query string loses everything after the first parameter. A path segment with a slash turns into two segments and returns a 404. Percent-encoding removes the ambiguity by replacing each reserved character with an escape the parser treats as data.Encoding choices across the cluster
Three encodings show up in the same debugging session and are easy to confuse. **Percent-encoding**, here, makes a value safe inside a URL. **Base64**, in [Base64 Encoder Decoder](/developer-tools/base64-encoder-decoder), makes arbitrary bytes safe inside a text channel. **JSON string escaping**, handled implicitly by [JSON Formatter](/developer-tools/json-formatter), makes a value safe inside a JSON document.
Applying the wrong one, or applying the right one twice, produces the classic double-encoded string full of
%2520 sequences. If you see that, decode until the value stops changing, then encode exactly once.Which core developer tools sit in this cluster?
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