HWP and HWPX: what the difference means for your file
HWP 5.0 stores its document records in a binary container. HWPX packages XML and related resources in ZIP. That changes how software reads the file, while tables, fonts and page layout still require careful interpretation.
The name is similar; the container is different
A HWP 5.0 file contains named streams holding the file header, document properties, body records and embedded data. A program must decode those binary records to recover the document. Reading the file as plain text will not produce a reliable transcript.
HWPX has a ZIP package structure. Its principal document parts are XML, with related resources stored in the package. Hancom describes HWPX as based on OWPML, the Korean standard KS X 6101. An XML-based package is easier to inspect structurally, but a ZIP reader alone cannot turn it into a formatted document.
An extra x does not make it a Word file
Both extensions describe Hancom document formats. DOCX is a separate target format with its own document model. A converter must interpret the source paragraphs, tables, notes and pictures, then write corresponding structures in the target. Merely changing the filename to end in .docx leaves the original bytes untouched.
The same distinction applies when an attachment has the wrong extension. HanOpen identifies the file from its content before choosing a parser. A format mismatch notice is useful evidence about the attachment, not a reason to repeatedly rename it. Keep the original name and a copy when investigating a file received from someone else.
HWPX still needs document-level interpretation
An XML tag can identify a table cell, but the reader still has to decide where that cell belongs, how far it spans, and what its nested content contains. A drawing can hold text inside another object. A paragraph can contain note references, a picture, an equation or a link as well as ordinary letters.
HanOpen maps the two input formats into one intermediate document model. Shared output code then produces DOCX, Markdown, HTML or text. This gives the outputs a consistent set of warnings and limitations. It does not mean the two source parsers encounter exactly the same structures in every document.
What our mixed corpus tells us
The real-world sample collected for this project contains 15 documents: 11 HWP 5.0 files and four HWPX files. One of those HWPX files has an encrypted body and is deliberately blocked. This is a small engineering sample, not a survey of all documents published in Korea.
In the broader conversion check recorded on 7 September 2026, 31 HWP inputs and 10 HWPX inputs produced DOCX files that opened in Word 16 without repair prompts. Their table counts matched the expected counts and their text coverage reached at least 99%. These measurements support a limited conversion result, not a claim that either format is universally more compatible.
A newer container does not remove protection
Protection is a separate property from the file extension. A HWPX package may contain an encrypted body rather than readable section XML. Finding a ZIP signature or successfully listing the archive is therefore not enough to establish that its document can be converted.
This version of HanOpen does not decrypt distribution documents, password-protected files or DRM documents. If the tool reports one of those conditions, ask the author for a permitted unprotected source. An old HWP 3.x file presents a different issue: it needs a parser for that earlier generation, which this version does not include.
Choose an output around the next task
For editing, choose DOCX and inspect tables and page breaks after opening it. For a web page or a readable archive, HTML keeps supported pictures within one file. For a text-based publishing workflow, Markdown offers ordinary text and either separate image assets or embedded images. Plain text is useful when wording matters more than styling.
You do not need to convert HWPX back to HWP as an intermediate step for these outputs in HanOpen. Both parsers feed the same output path directly. Adding an unnecessary conversion creates another result to inspect and another opportunity for document features to be simplified.
Keep the original and a visual reference
A text-rich report may survive conversion in a useful form while still gaining a page or moving a signature block. A tightly designed application form is more sensitive to font widths, margins and floating objects. Neither filename extension establishes that a converted copy meets a submission template.
Store the original file together with the result. If the author can provide a reference that shows the intended pages, compare key positions against it. Check the recipient’s required format before deciding what to send. The format accepted by a submission portal is an operational requirement, separate from what a browser can read.
Open documentation is not a universal support guarantee
Hancom publishes documentation for HWP and OWPML, including material covering older format generations. The availability of a specification gives implementers information to work from. Each application still has to implement the relevant structures and test them against real files.
Our public support summaries describe what HanOpen records or simplifies. They are more useful for deciding whether to try a particular file than a broad statement that HWPX is “open” or that HWP is “legacy.” Read the warnings produced for your document, then check the output in the application where you will actually use it.