MXML is an XML-based user interface markup language used by the Adobe Flex framework to declaratively lay out components, containers, and data bindings for rich internet applications.

Is my MXML data secure?

Yes. All parsing is done in your browser using JavaScript. No data is sent to our servers, so your MXML never leaves your device.

Can I format minified MXML with this tool?

Yes. The Format button re-indents minified or single-line MXML so the component hierarchy is easy to read. It only changes the line breaks and indentation between tags: element order, attributes, comments, CDATA blocks such as and every text value stay exactly as written, so the formatted file still describes the same Flex layout.

Does the viewer validate MXML syntax?

It validates the underlying XML structure as you type, flagging unclosed tags, mismatched elements, and other malformed markup so you can correct errors before exporting.

What file types can I open?

You can upload .mxml files or paste any well-formed XML-based markup. Because MXML is built on XML, the tree view and formatter also work with general XML snippets.

How do I open an MXML file?

Work out which kind it is first: drop it into the viewer above and match the root element against the table on this page. For reading, any text editor or this viewer will do. Building a Flex interface needs the Apache Flex SDK or the ActionScript & MXML extension for VS Code, and process-mining logs are analysed in ProM.

Is there an online MXML file editor?

Yes — the input pane here is editable. Changes are re-checked as you type, and Download saves exactly what is in the editor. The saved file is called formatted.mxml, so rename it before it replaces the original, for example a settings file in the game's SETTINGS folder.

Open MXML File Online – Free MXML Viewer & Editor

Open an .mxml file in your browser: view the Flex markup as a tree, edit it, format, validate and download the result. Free, no install, nothing uploaded.

Paste or upload an MXML file and this viewer instantly renders its Adobe Flex markup as a collapsible tree, showing every component tag, attribute, and nested child. It validates the XML syntax as you type, formats minified MXML for readability, and lets you copy or download the cleaned result. All parsing runs locally in your browser.

MXML Input

0 chars

MXML Viewer

Enter MXML to view structure

Key Features

✓Tree View: Navigate complex MXML structures easily with a collapsible tree view.
✓Validation: Automatically validate your MXML syntax as you type.
✓Privacy First: All processing happens locally in your browser.
✓Formatting: Beautify minified MXML for better readability.

Three unrelated file types use the .mxml extension

The extension alone doesn't tell you which program wrote the file. Drop it into the viewer above and look at the root element — that is the quickest way to tell them apart.

Origin	What the file holds	How to recognise it	What you can do here
Apache Flex (handed by Adobe to the Apache incubator in 2011)	The interface layout of a Flex application; together with ActionScript, the compiler turns it into a SWF or an AIR app	A root element such as <s:Application> declaring xmlns:fx="http://ns.adobe.com/mxml/2009" (Flex 4 onwards)	Walk the component tree and its attributes; the interface itself isn't drawn — that takes the Flex compiler
Process-mining event log (Mining eXtensible Markup Language, 2003)	Recorded runs of a business process: cases and their events; ProM's native input until XES (IEEE 1849) took over	<WorkflowLog> → <Process> → <ProcessInstance> → <AuditTrailEntry>, with <WorkflowModelElement>, <EventType>, <Timestamp>, <Originator>	Expand cases and events one at a time; process discovery and conformance checking happen in ProM
No Man's Sky settings files	Game settings in the Binaries/SETTINGS folder, e.g. GCMODSETTINGS.MXML (mod load order and the DisableAllMods switch) and TKGRAPHICSSETTINGS.MXML (graphics)	<Data template="…"> holding <Property name="…" value="…"> pairs; file names are usually upper-case	Read and change values; the download is named formatted.mxml, so rename it before it replaces the game's file

Software that opens .mxml files

There is no MXML media type in the IANA registry; because the content is XML, servers and browsers handle it as application/xml or text/xml (RFC 7303).

Software	Platform	What it does with .mxml	Status
Any plain-text editor (Notepad, TextEdit, VS Code…)	Windows / macOS / Linux	Opens, edits and saves all three kinds as XML text	Built in or free
Apache Flex SDK (mxmlc compiler)	Command line	Compiles Flex MXML plus ActionScript to SWF, or packages it as an AIR app	Apache top-level project since December 2012; SDK 4.16.1 released November 2017. Browser support for Flash Player ended at the end of 2020; AIR output is still supported
ActionScript & MXML extension for VS Code (Bowler Hat)	Windows / macOS / Linux	Completion, refactoring and breakpoint debugging in MXML; Adobe AIR, Flash Player and Apache Royale workflows	Open source, community-supported
Moonshine IDE	Desktop and cloud	Free, open-source IDE for AS3, Apache Flex, Apache Royale and Feathers	Free, open source
Adobe Flash Builder	Eclipse-based	Former official Flex IDE, called Flex Builder before version 4	Final version 4.7 (December 2012); Adobe core support ended in 2017, extended support in 2019
ProM	Java desktop app	Process-mining framework; early versions read MXML as input, later replaced by XES	Open source (GPL core, plug-ins mostly LGPL)

How to Use the MXML Viewer

1
Upload or paste your MXML
Drop an .mxml file into the uploader or paste your Adobe Flex markup directly into the input panel.
2
View the structure
The viewer parses the markup and renders it as an interactive, collapsible tree so you can navigate components, attributes, and nested children.
3
Format and validate
Use the Format button to beautify minified MXML; invalid XML is flagged immediately so you can fix syntax errors before exporting.
4
Copy or download
Copy the formatted MXML to your clipboard or download it as a file for use in your Flex project.

References

W3C — Extensible Markup Language (XML) 1.0
The W3C specification defining XML syntax, the foundation on which MXML markup is built.
MDN — XML introduction
A practical overview of XML structure, elements, and attributes that apply to MXML documents.

Related Tools

XML Viewer

View and explore any XML document in a collapsible tree structure.

XML to JSON

Convert XML or MXML markup into a structured JSON object.

XML Minifier

Compress XML by stripping whitespace and comments for smaller files.

SVG Viewer

Preview and inspect SVG XML markup with a live render.

Frequently Asked Questions

What is MXML?: MXML is an XML-based user interface markup language used by the Adobe Flex framework to declaratively lay out components, containers, and data bindings for rich internet applications.
Is my MXML data secure?: Yes. All parsing is done in your browser using JavaScript. No data is sent to our servers, so your MXML never leaves your device.
Can I format minified MXML with this tool?: Yes. The Format button re-indents minified or single-line MXML so the component hierarchy is easy to read. It only changes the line breaks and indentation between tags: element order, attributes, comments, CDATA blocks such as <fx:Script> and every text value stay exactly as written, so the formatted file still describes the same Flex layout.
Does the viewer validate MXML syntax?: It validates the underlying XML structure as you type, flagging unclosed tags, mismatched elements, and other malformed markup so you can correct errors before exporting.
What file types can I open?: You can upload .mxml files or paste any well-formed XML-based markup. Because MXML is built on XML, the tree view and formatter also work with general XML snippets.
How do I open an MXML file?: Work out which kind it is first: drop it into the viewer above and match the root element against the table on this page. For reading, any text editor or this viewer will do. Building a Flex interface needs the Apache Flex SDK or the ActionScript & MXML extension for VS Code, and process-mining logs are analysed in ProM.
Is there an online MXML file editor?: Yes — the input pane here is editable. Changes are re-checked as you type, and Download saves exactly what is in the editor. The saved file is called formatted.mxml, so rename it before it replaces the original, for example a settings file in the game's SETTINGS folder.