YAML to XML Converter
Convert YAML documents to well-formed XML with tag name sanitization, attribute mapping, and automatic array expansion. Runs entirely in your browser.
How to Use
Converting YAML to XML bridges human-friendly configuration with enterprise XML ecosystems. This converter transforms any valid YAML document into well-formed XML, handling nested objects, arrays, attributes, and edge cases like invalid tag names. Here is how to use it:
- Paste your YAML into the input area on the left. The tool accepts any valid YAML 1.2 document including configuration files, data exports, Kubernetes manifests, and API payloads.
- Configure conversion options in the sidebar. Set the root element name for multi-key documents, choose indentation, configure the attribute prefix character, and toggle the XML declaration header.
- Review the XML output in the right panel. YAML mappings become XML elements, sequences expand into repeated elements, and prefixed keys map to XML attributes.
- Copy or download the result. Use the copy button for clipboard access or download as an
.xmlfile for integration into your project.
YAML to XML Mapping Rules
YAML and XML represent structured data with fundamentally different syntax. Here are the conversion rules this tool applies:
- Key-value pairs become XML elements.
name: DevToolkitproduces<name>DevToolkit</name>. Scalar values (strings, numbers, booleans) become the text content of their element. - Nested mappings become nested XML elements. Each level of YAML indentation maps to a child element in the XML tree, preserving the full hierarchical structure.
- Sequences (arrays) expand into repeated sibling elements sharing the parent key name. A YAML list under
itemswith three entries produces three<items>child elements, following the standard XML serialization convention. - Attribute prefix keys (default
@) become XML attributes. A key@id: 5inside a mapping produces anid="5"attribute on the parent element. The#textkey sets the element's text content when attributes are present. - Null values produce self-closing tags. A YAML key with a null value (
metadata: ~ormetadata:) becomes<metadata/>in the XML output. - Tag name sanitization handles YAML keys that are not valid XML names. Keys starting with digits get an underscore prefix, and special characters are replaced. For example,
1st-placebecomes_1st-place.
About This Tool
How the Serialization Works
This YAML to XML converter uses a two-stage pipeline running entirely in your browser. First, the js-yaml library parses the YAML string into a JavaScript object tree. The js-yaml parser implements the YAML 1.2 specification, correctly handling multi-line strings, anchors and aliases, flow mappings, tagged values, and all standard scalar types including dates, booleans, and numbers.
Second, a custom recursive serializer walks the JavaScript object tree and builds the XML string. Unlike many converters that rely on heavy XML serialization libraries like fast-xml-parser, this tool uses a purpose-built serializer that produces clean, indented XML with zero extra dependencies. The serializer handles attribute extraction from prefixed keys, text content via the #text convention, array expansion, null-to-self-closing conversion, and proper XML character escaping for ampersands, angle brackets, and quotes.
Tag Name Sanitization
XML has strict rules for element and attribute names defined in the W3C XML specification. Names must start with a letter (A-Z, a-z) or underscore, and subsequent characters can include letters, digits, hyphens, underscores, and periods. YAML has no such restrictions on mapping keys — keys can be numbers, contain spaces, or start with special characters. This converter automatically sanitizes non-compliant keys by replacing invalid characters with underscores and prepending an underscore if the key starts with a digit. A warning is displayed for each sanitized key so you can review the changes and update your source YAML if needed.
Attribute Mapping Convention
Since YAML has no concept of attributes (only key-value pairs), a prefix convention is used to distinguish which keys should become XML attributes versus child elements. The default prefix is @, matching the convention used by popular libraries like xmltodict (Python) and fast-xml-parser (JavaScript). This convention also makes the output of this converter directly compatible with DevToolkit's XML-to-YAML converter, enabling round-trip conversion without data loss. You can change the prefix to _, $, or any string to match your project's conventions.
Why Use This Tool
When to Convert YAML to XML
While YAML has become the dominant configuration format in modern DevOps and cloud-native ecosystems, XML remains deeply entrenched in enterprise systems, Java frameworks, and data interchange standards. YAML to XML conversion is essential in several real-world workflows:
- Java/Spring framework integration — Spring Boot supports YAML configuration files, but many Spring modules, legacy applications, and third-party Java libraries still require XML bean definitions, context files, or Maven
pom.xmlconfigurations. Converting YAML drafts to XML bridges the gap between modern authoring and legacy consumption. - XML feed generation — RSS feeds, Atom feeds, and sitemap.xml files must be valid XML. Authoring feed data in YAML's concise syntax and converting to XML produces cleaner source files that are easier to maintain in version control than raw XML.
- SOAP and enterprise web services — SOAP APIs require XML request and response envelopes. Defining SOAP payloads as YAML data structures and converting to XML simplifies template authoring, especially for automated testing and API documentation generation.
- .NET and MSBuild configurations — The .NET ecosystem uses XML for project files (
.csproj), NuGet package configs, and application settings (web.config,app.config). Teams that prefer YAML for readability can draft configurations in YAML and convert to the required XML format. - Data interchange with XML-native systems — Financial services (FIX/FIXML), healthcare (HL7/FHIR), and government systems often mandate XML data formats. Converting YAML data exports into compliant XML enables integration with these regulated ecosystems without manual XML authoring.
Privacy and Security
This converter runs entirely in your browser using the js-yaml library for parsing and a custom serializer for XML generation. No data is transmitted to any server, stored remotely, or logged. Your YAML content — which may contain database credentials, API keys, infrastructure secrets, or proprietary configurations — never leaves your device. This makes the tool safe for converting sensitive configuration files subject to SOC 2, HIPAA, PCI-DSS, or other compliance requirements.