XML has layers of validity
XML Formatter, Validator, Tree Viewer & XPath Tester Online
Readable indentation is only the first layer. A reliable workflow distinguishes parse errors, schema rules, namespace context, and query results.
Follow the document from text to matched node
- 1
Source
Encoded markup and declarations
- 2
Well-formed XML
Balanced elements, quoted attributes, one root
- 3
Namespace-aware tree
Expanded names, attributes, text nodes
- 4
Schema validity
XSD types, order, occurrence, constraints
- 5
XPath result
Nodes selected in an explicit context
Well-formed is not the same as valid
Well-formed XML
A parser can build one unambiguous XML document.
Schema-valid XML
The document also satisfies the vocabulary and types defined by its XSD.
<invoice total="ten"/> may be well-formed while violating an XSD decimal type.NAMESPACE CONTEXT
Prefixes are aliases, namespace URIs are identity
The same namespace can use different prefixes. XPath queries need an explicit prefix-to-URI map even when the source uses a default namespace.
inv → urn:example:invoicexsi → http://www.w3.org/2001/XMLSchema-instance//inv:item[@status="open"]External entities are a security boundary
DevSexy does not fetch external DTDs, schemas, or entity URLs while parsing. This avoids turning a formatter into an XXE or network-discovery client.
● External entity resolution: disabled
● Input processing: browser-local
Pair the document with the right authority
| Task | Required input | Operation |
|---|---|---|
| Make it readable | XML only | Format |
| Check grammar | XML only | Well-formedness |
| Check business vocabulary | XML + XSD | Schema validation |
| Select nodes | XML + namespace map | XPath |
XML tooling questions
- 01Does formatting validate an XML document?
- Formatting requires parseable input, but it does not prove conformance to an XSD or business vocabulary.
- 02Why does my XPath return no results?
- A default namespace is a common cause. Bind its URI to a query prefix and use that prefix in the expression.
- 03Will the tool load an external schema URL?
- No. External resource resolution is disabled; provide the schema content directly when schema validation is supported.