What is an XML namespace?

An XML namespace is a URI that disambiguates element and attribute names so vocabularies from different standards can coexist in one document. The URI is an identifier, not a location — nothing is usually fetched from it. It is bound to a prefix with an xmlns declaration.

Does the prefix matter?

No. The prefix is just a local alias for the namespace URI; only the URI is significant for matching. Conventional prefixes like soap, xsd or dc improve readability and interoperability with tools, but a document can choose any prefix or use a default xmlns.

Why do SOAP 1.1 and 1.2 have different namespaces?

Each major version of a standard mints a new namespace URI so processors can tell them apart. SOAP 1.1 uses schemas.xmlsoap.org/soap/envelope/ while SOAP 1.2 uses www.w3.org/2003/05/soap-envelope. Sending the wrong one causes version mismatch faults.

Is the trailing slash or fragment part of the URI?

Yes — the namespace URI must match character for character, including any trailing slash or # fragment. www.w3.org/2000/svg and www.w3.org/2000/svg/ are different namespaces, so copy the exact string rather than retyping it.

Does this tool send my query anywhere?

No. The namespace list is bundled into the page and filtered entirely in your browser. Nothing is uploaded, logged or stored.

Common XML Namespaces Reference

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Why XML uses namespaces

XML namespaces let one document mix vocabularies — an SVG image inside XHTML, a Dublin Core element inside RSS — without name collisions. Each vocabulary is identified by a namespace URI bound to a prefix. This reference lists the URIs for the standards you meet most often, with their conventional prefixes and a copy button so you never mistype one.

How it works

A namespace is declared with an xmlns attribute that binds a prefix to a URI, then used by qualifying names with that prefix:

<env:Envelope xmlns:env="http://www.w3.org/2003/05/soap-envelope">
  <env:Body/>
</env:Envelope>

The URI is an opaque identifier compared by exact string equality — case, slashes and fragments all count. The prefix is purely local: env, soap or a default xmlns with no prefix all work as long as they map to the right URI. This tool filters the table as you type and copies the exact URI to your clipboard.

Tips and notes

The namespace URI is matched literally — copy it, do not retype it.
A default xmlns="..." applies to the element and all unprefixed descendants.
xml is permanently bound to http://www.w3.org/XML/1998/namespace (e.g. xml:lang).
Namespace URIs rarely resolve to anything; treat them as identifiers, not links.