How this works: this page parses the .reg text format Windows' own Registry Editor writes and reads — both the modern "Windows Registry Editor Version 5.00" format (Unicode) and the legacy REGEDIT4 format (ANSI) — directly in your browser tab. The file is read with the File API and never uploaded anywhere; nothing is imported into any registry.
Every value type is decoded, not just shown as raw hex: strings, expandable strings, DWORDs and QWORDs (32- and 64-bit numbers), multi-string lists, and binary data. A key or value prefixed with a minus sign in the file (Registry Editor's own deletion syntax) is called out as a deletion, not confused with a normal change.
Why check a .reg file before running it
Double-clicking a .reg file merges it straight into the registry with no preview and, by default, no undo. It's also a common way to distribute a persistence mechanism, a browser hijack, or a policy tweak disguised as a "fix" — the file itself is plain text, but nothing shows you what it actually changes until it's already done. This page decodes it first, so you can see every key and value before deciding whether to import it for real.
Troubleshooting
My file won't open at all
This page expects a standard Registry Editor export: the first line should read Windows Registry Editor Version 5.00 or REGEDIT4. A file that's been re-saved with a text editor in the wrong encoding, or that isn't actually a .reg export, will be rejected rather than guessed at.
A value shows as "could not decode"
This means the byte data after a hex: or hex(N): prefix didn't parse as a valid comma-separated byte list — usually a sign the file was hand-edited or corrupted. Everything else in the file is still shown normally.
What does "will be deleted" mean?
A key written as [-Key\Path], or a value written as "Name"=-, tells Registry Editor to remove that key or value rather than set it. This page shows those the same way Registry Editor would apply them, rather than treating the minus sign as ordinary data.
Prefer the command line?
That's the Windows command that actually applies a .reg file — there's no built-in command-line way to preview one first, which is the gap this page fills. On Windows, Get-Content file.reg in PowerShell will at least show you the raw text.