I maintain a comparison page about XstReader, an open-source desktop viewer for Outlook .pst and .ost files. For a while the page treated the whole project as Windows-only. One fact line read "Windows desktop only — no macOS or Linux build." The body said there was no macOS build and no Linux build.

That wording is true of the viewer. It is not true of the repository.

What the project's README actually says

I opened the README at github.com/Dijji/XstReader while writing this. Two products live in the same tree:

  • XstReader, the three-pane viewer, "requiring only .Net Framework 4, and with no dependency on any Microsoft Office components."
  • XstPortableExport, "a portable version based on .Net Core 2.1 that can be run on Windows, Mac, Linux etc."

The portable tool is a command-line exporter, not a second viewer. The same README is explicit about what that portability costs:

in order to remain portable, two areas of functionality have to be #ifdef'd out in order not to create a framework dependency and so tie the program to Windows. These are support for RTF body formats, and support for MIME decryption.

A Windows command-line exporter, XstExport, is listed as well. The cross-platform binary is XstPortableExport.

I also fetched the GitHub Releases API for the repository today. The latest release is still tagged v1.14, published 2 January 2021, 18:27 UTC. I did not install or run either exporter.

What the page says now

The comparison row and the fact list now limit "Windows only" to the viewer, and name XstPortableExport as a command-line exporter that the README says also runs on Mac and Linux. A fact line records the latest release as v1.14, 2 January 2021. A new FAQ, "Is there an XstReader for Mac?", states the same split: no viewer for Mac; a portable exporter that writes messages out as .html, .rtf or .txt with attachments in folders, without RTF body support or MIME decryption in that build, and with no window for reading.

The corrected direct answer still points at two ways to read mail on a Mac: a terminal conversion with readpst, or opening the file in the browser. XstPortableExport is an export path, not a replacement for those.

A test file, tests/xstreader-claims.test.ts, forbids the old "no macOS or Linux build" sentences, requires the page to name XstPortableExport, .NET Framework 4, and v1.14, and checks that the new FAQ mentions the two omitted features. I read that test. I did not run the suite.

Takeaways

  • A repository can ship more than one program. A single "Runs on" cell that describes only the GUI will misstate the project.
  • Read the project's own README before repeating a platform line. The portable exporter and the two #ifdef'd features were documented there.
  • "It runs on a Mac" is still the wrong sentence if the Mac build cannot show a mailbox. Say that it exports files, and say what it leaves out.
  • Pin the distinction in a test that fails if the old, flatter wording comes back.

The same project is listed in the PST row of the email archive formats guide.

Disclosure: I built it. Mailward, the site these pages are on, is my own project.

Source note (2026-11-14): I read Mailward commit 2076acf (AuthorDate 2026-11-12 11:11:32 +0800), the current XstReader page copy, and the new tests. I also opened the upstream README and fetched https://api.github.com/repos/Dijji/XstReader/releases/latest (200, tag v1.14, published_at 2021-01-02T18:27:21Z). I did not run the test suite, and I did not run XstPortableExport myself.