The desktop application
The solver on this page runs in your browser on a compact trigram model, and it is free for as long as this site exists. The desktop build is the full engine: 50 ciphers including the M-94 wheel cipher, Quagmire III and the polyalphabetic sum-clock, quadgram models in six languages, layered-puzzle unwrapping six levels deep, and a search budget you set yourself.
Buttcrack for Windows
The complete cipher breaker as a Windows program. One installer, nothing else to fetch — the language models and the interface are inside it. Install it on a machine that has never seen Python and it works.
version 1.1.0 · Windows 10 / 11, 64-bit · no admin rights needed
Buy for $39.99Payment is handled by Stripe. The download appears immediately after checkout — no account, no licence key, no subscription. One payment, yours to keep, on as many of your own machines as you like.
What you get
Two programs sharing one runtime:
- Buttcrack — the Start-menu app. It starts a private server on
127.0.0.1, opens the solver in your browser, and sits in the notification area until you close it. - buttcrack.exe — the command line, optionally added to your
PATHduring setup, sobuttcrack "Wkh txlfn eurzq ira"works in any terminal, reads files and pipes, and prints JSON for scripting.
It installs per-user into %LOCALAPPDATA%, so there is no
administrator prompt, and it uninstalls from Add/Remove Programs like anything
else. No account, no licence server, no telemetry, no update checks, no expiry.
Nothing leaves your machine
The desktop build is a local web server, not a web service. The address it opens is bound to loopback only — unreachable from your own network, let alone the internet — and the language models are inside the installer, so every feature works with the network cable out. That is the entire reason it exists: a document you are not allowed to paste into a website can still be worked on using hardware you control.
What it breaks that the browser version does not
- All 50 ciphers, each with its own attack rather than a brute-force loop — including Playfair, bifid, trifid, four-square, Hill, the M-94 wheel cipher, Quagmire III, Myszkowski and AMSCO.
- Six languages. English with an 80,000-word dictionary distilled from
a 25-million-word corpus, plus French, German, Italian, Latin and Spanish n-gram models —
and
--language autoto probe all six. - Deeper layers. Encodings and ciphers stacked six deep, unwrapped and reported as a chain, with the key of the cipher that actually hid the message.
- Your own time budget. Hard puzzles get minutes instead of the seconds a web page can spare, and the search reports what it tried and what it scored.
Windows will warn you the first time
The installer is not code-signed, so Windows SmartScreen shows a blue “Windows protected your PC” dialog. That is a statement about a certificate that costs several hundred dollars a year, not about the file. Click More info, then Run anyway — and check the SHA-256 above first if you would rather not take anyone's word for it.
Requirements
Windows 10 or 11, 64-bit. Roughly 60 MB of disk once installed. No internet connection is required at any point after the download, and none is used. There is no macOS or Linux installer.
Frequently asked questions
How do I get the file after paying?
Stripe sends you straight to a download page the moment the payment clears, and your receipt arrives by email. The download page stays valid, so bookmark it. If you lose it, reply to the Stripe receipt and it will be sent again.
Do I need Python installed?
No. The installer contains its own copy of Python, the six language models and the interface. Nothing else has to be present on the machine and nothing is downloaded during installation.
Does it need administrator rights?
No. By default it installs into your own user profile, so there is no UAC prompt at all. The first page of the installer offers a machine-wide install if you would rather have one, and that does need an administrator.
Why does Windows say the publisher is unknown?
Because the installer is not code-signed. SmartScreen is reporting the absence of a certificate rather than anything it found in the file. Click More info, then Run anyway — and check the published SHA-256 if you want independent confirmation of what you downloaded.
Does it send my ciphertext anywhere?
No. The desktop build runs a web server bound to 127.0.0.1, which is your own machine and is not reachable from your network or the internet. There is no analytics, no update check and no account. Disconnect from the network entirely and every feature still works.
How is this different from the free solver on this page?
The browser solver uses a compact trigram model and covers the common ciphers. The desktop build has all 50 ciphers including Playfair, Hill, the M-94 wheel cipher and Quagmire III, quadgram models for English, French, German, Italian, Latin and Spanish, layered unwrapping six levels deep, and a search budget you can raise for hard problems.
Can I install it on more than one machine?
Yes. One payment covers your own machines — desktop, laptop, a virtual machine. There is no licence key and nothing to activate, so there is nothing to juggle.
How do I uninstall it?
Settings, then Apps, then Buttcrack, then Uninstall — or the Uninstall shortcut in its Start menu folder. It removes the program, the shortcuts and the PATH entry if you added one. It leaves nothing behind, because it never writes anything outside its own folder.