CONVERT OPML → HTML (OPML to HTML)
Fast, secure OPML to HTML conversion. No registration required.
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Studio Panel
Ghostscript + QPDFHOW TO CONVERT OPML → HTML
Provide the document
Select a OPML file. Very large documents (100+ pages) may take a few extra seconds to render completely.
Render to HTML
LibreOffice plus supporting filters translate the OPML into a fully-formed HTML with no structural drift.
Save the result
The converted HTML streams back over HTTPS; open in the target application to verify formatting.
Setup: OPML is a document format oriented around a particular office suite or publishing pipeline. Goal: an interchangeable HTML. Converting OPML to HTML online saves installing office suites you use once a year. Upload the document, let the server render it through the same pipeline large publishers use, and download a polished HTML that keeps its original structure and typography. One more beat. OPML is a document format oriented around a particular office suite or publishing pipeline. Receiving format: HTML is the web's HyperText Markup Language, the universal document format for browsers.
Why convert OPML to HTML
The driver for a OPML to HTML conversion is almost always the downstream audience: the editor, archivist, signer or reader who expects a HTML. Doing the conversion in a proper rendering pipeline, rather than hoping the receiving tool will figure it out, avoids layout drift and font substitutions.
OPML vs HTML — Technical specifications
Side-by-side comparison of the technical details.
OPML
- MIME type
- text/x-opml
- Extension
- .opml
- Format
- XML with nested <outline> elements
- Standard
- OPML 2.0 (2006)
- Primary use
- RSS subscription interchange
- MIME Type
- text/x-opml
- Category
- Documents & Text
- Full Name
- OPML Outline
- Conversion Engine
- PANDOC
HTML
- MIME type
- text/html
- Extension
- .html
- Standard
- HTML Living Standard (WHATWG)
- MIME Type
- text/html
- Category
- Documents & Text
- Full Name
- HTML Document
- Conversion Engine
- PANDOC
- Extensions
- .html, .htm
- Character encoding
- UTF-8 (recommended)
- Element count
- ~110 in current spec
| Specification | OPML | HTML |
|---|---|---|
| MIME type | text/x-opml | text/html |
| Extension | .opml | .html |
| Format | XML with nested <outline> elements | — |
| Standard | OPML 2.0 (2006) | HTML Living Standard (WHATWG) |
| Primary use | RSS subscription interchange | — |
| MIME Type | text/x-opml | text/html |
| Category | Documents & Text | Documents & Text |
| Full Name | OPML Outline | HTML Document |
| Conversion Engine | PANDOC | PANDOC |
| Extensions | — | .html, .htm |
| Character encoding | — | UTF-8 (recommended) |
| Element count | — | ~110 in current spec |
OPML vs HTML — Strengths and limitations
What each format does best, and where it falls short.
OPML Strengths
- Standard RSS subscription interchange format.
- Simple XML — easy to parse and generate.
- Highly extensible via arbitrary attributes.
- Supported by every major outline and RSS tool.
Limitations
- XML verbosity — larger than a JSON-based equivalent.
- Specification is loose — different tools disagree on edge cases.
- Primary use (RSS reading) has shrunk dramatically since Google Reader.
HTML Strengths
- Universal — every browser, OS, email client, and document reader displays HTML.
- Plain text, human-readable, grep-able, and diffable in git.
- Flexible — pages render even with broken or partial markup (error-tolerant parser).
- Carries structure, styling (CSS), and behavior (JavaScript) in one file.
- Accessibility-friendly when written with semantic tags and ARIA attributes.
Limitations
- Error tolerance allows sloppy markup to hide real bugs.
- Rendering depends on browser engine — pixel-perfect cross-browser output is an art form.
- Security-sensitive — unsafe HTML can execute scripts or leak data (XSS vulnerabilities).
Quality & Compatibility
The conversion preserves document structure rather than pixel-perfect rendering: a paragraph in OPML is a paragraph in HTML, not a bitmap snapshot. That means you can still edit and search the HTML. If you need exact visual fidelity (for legal or print workflows), export to PDF as the final step.
Tips for Best Results
- Run a spell-check in the HTML after conversion — occasionally hyphenation or language tagging shifts and typos become invisible to the original checker.
- Include fallback generic fonts (sans-serif, serif) in your style definitions so the HTML degrades gracefully when a font is missing on a viewer device.
- For archive-quality output, export to PDF/A after converting to HTML; this locks the document against future rendering drift.
Frequently Asked Questions
Yes, as long as the fonts are standard (system fonts or common office fonts like Arial, Calibri, Times, Helvetica). Custom corporate fonts survive if they are embedded in the source document; otherwise the conversion substitutes the closest available match, which can shift line breaks by a character or two.
Yes. Inline images are embedded into the HTML at full resolution, editable tables become native HTML tables, and hyperlinks keep their URLs. Complex features unique to OPML — macros, form fields, track-changes — are mapped where an equivalent exists in HTML and flattened into static content otherwise.
All uploads go over TLS, files are processed in isolated containers and both the source and the output are deleted within two hours. No account is required, file contents are never indexed or used for training, and the paid plan adds a signable data-processing agreement for regulated workflows.
OPML Outline
Source formatOPML (Outline Processor Markup Language) is an XML format for structured outlines and lists. It is most widely used for exchanging RSS feed subscription lists between podcast apps and feed readers, and for hierarchical note-taking.
HTML Document
Target formatHTML is the standard markup language for web pages. As a conversion target or source, it carries text content with structural and formatting information that can be extracted or repurposed.
Going the other way? Convert HTML back to OPML with the same engine.
Common Use Cases
Share across platforms
Send HTML files to anyone without worrying about whether they have the right software for OPML.
Embed in documents
Drop HTML output into Word, Google Docs, PowerPoint, Notion or a website without conversion warnings.
Optimize size
HTML often produces smaller files than OPML for web, email and storage.
Archive & future-proof
Store in a widely-supported format that will still open on future operating systems without legacy plugins.
OPML vs HTML — Typical file sizes
Approximate file sizes for common scenarios.
- Typical RSS reader export (50 feeds) 5-30 KB
- Deep outline (Scrivener novel plan) 20-200 KB
- Hello-world page < 1 KB
- Blog post (rendered HTML) 5-40 KB
- Modern SPA (initial HTML shell) 50-200 KB
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Related comparisons
See these formats side by side to understand which fits your use case best.
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