About ReinstallOS, and how the guides are written
ReinstallOS is a set of walkthroughs for the one job that has to happen before any software recommendation is useful: getting a clean copy of Windows or macOS back onto the machine. It is not a download portal, not a mirror, and it does not host a single installer. Every file it points you at comes from Microsoft's or Apple's own servers.
Why this exists at all
Reinstalling an operating system is a solved problem with terrible documentation. The instructions exist, but they are spread across support pages, they assume you already know which Mac you have, and the search results around them are dominated by sites that want to hand you a “clean” ISO with something added.
That last part is the reason this site is careful about a seemingly pedantic detail: which build of the installer you use. A reinstalled machine is supposed to be a known-good starting point. Install it from a repackaged image and you have started over with an unknown, then inherited the reputation of whoever actually packaged it. So we only ever point at the vendor.
What is on the site
- The Windows guide covers a clean install from a USB drive: the official ISO, writing the drive, the boot menu, partitioning, drivers, and what legitimately activates a licence.
- The macOS guide covers both Apple silicon and Intel, because the recovery steps differ between them: what to hold, which recovery you get, erasing the disk, and what happens to your data.
- The downloads page is a short list of vendor download pages, with the real hostname printed on every link so you can see where it goes before you click it. Each major source also has a page explaining which of its options to use and how it is commonly misused.
- The decision guides answer the question in front of a step: whether a clean install is needed at all, how to prove a backup restores, what the partition screen is showing, and what to do when the same fault survives a reinstall. The guides index lists them all.
How the guides are written
Button and menu names are quoted exactly as they appear on screen, because the whole point is that you can find them on your own machine. Where a name differs between versions, both are given. Labels are shown in boxed form like that, and a keyboard shortcut looks like this — macOS shows its modifier keys as glyphs (⌘, ⌥, ⇧) rather than the words Command, Option and Shift.
Where a step can destroy data, the page says so before you reach it, not in a footnote afterwards. That is deliberate: the warnings are the useful part.
What we check, and what we do not
Each factual claim is checked against the vendor's own documentation: Microsoft's support and specification pages, Apple's support articles and user guides, and the publisher sites of the USB writing tools we name. We check the wording of a screen label, a hardware requirement and a procedure, and we check that every link still resolves to the vendor's own domain. The full list is published on the sources page, and every article ends with the documents it was checked against.
What we do not do: we do not run benchmarks, measure performance, publish test scores or version comparisons, or claim a screenshot we did not take. We do not test every machine, every firmware version or every peripheral. We do not inspect a visitor's computer, validate their backup or confirm their licence. The guides describe a procedure and the decisions around it; they cannot see your hardware.
Where a widely copied instruction is wrong, we say so visibly rather than silently correcting it — a reader may already have seen the wrong version and needs to know which one to believe. Leaving Secure Boot on, using a 32 GB stick for a macOS installer, and the fact that reinstalling macOS keeps your data are three examples documented on this site.
Where the outside evidence comes in
We cite only first-party documentation and the publishers of tools we mention. We summarise, in our own words, only the part that changes a decision; we name the organisation and link to the original; and we add our own verdict. No review prose, star ratings, score tables or charts are reproduced. The citation policy sets out these rules in full.
What this site is not
It is not affiliated with, endorsed by, or sponsored by Microsoft Corporation or Apple Inc. Windows and macOS are trademarks of their respective owners, used here only to describe the software. It is also not a support desk: we cannot recover a machine for you, tell you whether your specific backup is intact, or advise on a business machine under a support contract.
How this site is paid for
As of 10 November 2026 there is no advertising on this site. There are no ad slots, no affiliate links, no sponsored placements and no commercial relationship with any software publisher. The site is a small editorial project; it currently earns nothing from the traffic it receives.
Every link to Microsoft or Apple is there because that is the only safe place
to get the file, and it would be there whether or not anybody paid. No link on
this site carries a referral identifier, and no placement is reserved for a
sponsor. If a commercial relationship is ever introduced, it will be disclosed
on this page, in the privacy policy, in the terms and in the footer before it
goes live, and ads.txt will be updated at the same time.
Our sister site InstallShelf ↗ covers what to install after the machine is running again. It follows the same disclosure: no advertising, affiliate links or sponsored placements today.
Corrections
Operating systems change, and a walkthrough that was correct last year can be misleading this year. If a step no longer matches what is on your screen, if a download page has moved, or if we have described a risk too lightly, write to us and we will correct it. A guide that is confidently wrong is worse than no guide, so corrections are welcome and taken seriously. Include the page URL and the vendor's current wording if you have it.
Contact
The contact page explains what to write about, what we cannot help with and what happens to a message. The address is [email protected].
For copyright and trademark complaints, see the copyright section of our terms, which lists the exact information we need from you.