Free tool
Schematron validator
Check the rules a grammar cannot express — that a total equals the sum of its lines — with each assertion reported against the nodes that failed it.
Loading tool…
Reference for these formats
UBL Invoice
The OASIS invoice document behind Peppol and most European e-invoicing mandates, splitting its vocabulary across three namespaces you must all declare.
XML Schema (XSD)
The dominant XML schema language: namespace-aware, richly typed, and itself written in XML — so schemas diff and version-track like the payloads they govern.
JATS article
The publishing interchange for journal articles, separating front matter, article body, and back matter such as references and acknowledgements.
Hit a parse error? Every common XML error explained.
Other free tools
- XML validatorCheck XML well-formedness, selected SOAP and XML Schema vocabulary rules, and optional XSD validity with concrete repair guidance.
- XSD validatorValidate an XML document against an XSD schema and get every violation with its line — required attributes, datatypes, element order and cardinality.
- Sitemap validatorCheck a sitemap.xml or sitemap index against the sitemaps.org protocol: URL counts, size limits, lastmod freshness and structure.
- RSS & Atom feed validatorCheck an RSS 2.0 or Atom 1.0 feed against its specification: required channel and entry elements, date formats, self links and duplicate identifiers.
- XPath explorerList every element path in a document with its occurrence count, depth and a sample value — plus the attributes declared on each.
- RELAX NG validatorValidate an XML document against a RELAX NG grammar (.rng) and get every violation with its line — the grammar DocBook, TEI and JATS ship as normative.
- XML minifierStrip the whitespace between elements using libxml2's own serializer — the only whitespace that can be removed without knowing the schema.
- XML canonicalizer (C14N)Produce Canonical XML 1.0, 1.1, or Exclusive C14N — the normalized byte stream signatures are computed over, and the only fair way to compare two documents.
- XML escape & unescapeEscape text so it survives inside an XML document, or resolve character references back — with the HTML-only entities that cause "Entity not defined" flagged.
- XPath testerRun an XPath 1.0 expression against a document and see what libxml2 returns — the same engine behind PHP's DOM, Python's lxml and Ruby's Nokogiri.
- XSD generatorInfer an XML Schema from a document you already have, with cardinality read from the document itself — and a guarantee that it validates what it came from.
- XML to JSON converterConvert an XML document to JSON, keeping attributes rather than discarding them and — by default — keeping every value as a string, not a guessed type.
- JSON to XML converterConvert JSON to XML, with @-prefixed keys becoming attributes and arrays becoming repeated elements — the exact inverse of our XML to JSON converter.
- CSV to XML converterTurn a table into XML — one element per row, column headers as element names — with the delimiter detected rather than assumed.
- Sitemap generatorTurn a list of URLs into a sitemap that passes our own sitemap validator — with the ampersands escaped, which is how hand-built ones usually break.
- XML to YAML converterConvert XML to YAML, quoting every value YAML would otherwise turn into a boolean, a number or a time — including the one that makes Norway false.
- XML to CSV converterTurn XML into CSV — one row per repeating record such as a sitemap URL or feed item, or one row per element path with counts and sample values.
- XML formatterIndent an XML document, or canonicalise it, using libxml2's own serializer — mixed content, CDATA, comments and prefixes all survive.
- XML diffCompare two XML documents structurally: which paths, attributes and namespaces were added, removed or changed — ignoring reordering and reindentation.
- DTD validatorValidate an XML document against a DTD — content models, attribute defaults, enumerations, and ID/IDREF resolution, with every violation named.
- Sample XML from XSDTurn a schema into a skeleton document that validates against it — the answer to a partner sending you an XSD and nothing else.
- XSLT transformerRun an XSLT 1.0 stylesheet against a document and see the output — with the network closed, so a stylesheet cannot fetch anything on your behalf.
- YAML to XML converterConvert YAML to XML through the same tree the JSON converter uses, so the two directions agree rather than each guessing separately.
Get started
Keep the documents you check, and watch them for changes.
A free workspace stores versions, extracts their structure for search, and re-checks monitored URLs on a schedule. Paste or upload up to 4 MB, or fetch a URL up to 5 MB.