Legal
lapstack is made by RAGTUX LLC, a Minnesota limited liability
company, and is free software under the MIT license. The binding text is the
LICENSE at the root of the source repository,
which ships with each program — in the browser app at
lapstack.app.ragtux.com/legal/LICENSE.txt;
what follows is that text in plain words, and where the two differ the
LICENSE wins.
The license, in plain words
lapstack is free software under the MIT license. The browser app, the desktop application, the command-line tool, the Lightroom plug-in and the source they are built from all come under it. The terms are short.
What you may do. Anything. Use lapstack for any purpose — personal, commercial, institutional — on as many machines as you like. Copy it, change it, merge it into something else, publish it, redistribute it, sublicense it, sell copies or build a product on it. There are no tiers, no keys, no caps, no commercial-use line and no honor system, because there is nothing to pay for.
The one condition. A copy, or a substantial part of one, carries the
copyright notice and the permission notice from the LICENSE. That is all the
license asks.
Your images are yours. RAGTUX claims no rights in anything you process with lapstack or anything it produces. Its output carries no watermark and no hidden mark, and it embeds nothing about you unless you ask it to (the optional content credentials manifest, signed with a key that never leaves your browser).
No warranty. lapstack is provided as it is, without a warranty of any
kind, and to the extent the law allows RAGTUX LLC is not liable for anything
that follows from using it — a lost shoot, a missed deadline, a corrupted
file. The LICENSE says this in capitals. Run your own stack through it and
judge the result; there is no charge, so there is nothing a refund could put
right.
Names. The license covers the software, not the names: see trademarks below.
Privacy
The short version: your images never leave your machine, and we do not know who you are. The longer version, which is the honest one, follows.
The browser app at lapstack.app.ragtux.com processes your frames inside the browser tab, on your own GPU. It makes no network request other than loading its own files from that hostname; it has no account, no cookie, no analytics, no crash reporting and no way to send an image anywhere. It remembers a few things in the browser's own storage so that the next visit starts where the last one ended: your settings and the last save options, which panels you collapsed, the folders you granted it for a project (a permission the browser holds, not a path we see), and, if you use content credentials, the self-signed certificate and key it made for you. All of it is in your browser, is readable by nobody else, and is gone when you clear the site's data. Close the tab and nothing of the session remains anywhere but the files you saved. The one link out of the app is the Support lapstack button, which opens a payment page run by Stripe in a new tab; what you enter there is handled under Stripe's privacy policy, and nothing about it comes back to the app. If you contribute, RAGTUX sees what Stripe reports of a payment — a name, an email address, an amount — and uses it for nothing but thanks and the books.
The desktop application is the browser app in its own window, with the same properties: no network requests, no updater, no telemetry.
The command-line tool and the Lightroom plug-in make no network requests at all.
This site sets no cookies and runs no analytics. It remembers your light or dark theme choice in the browser's storage, and its search runs against an index it downloads from itself. The fonts are served from here, not from a third party.
Our server keeps the ordinary access log a web server keeps — the requesting address, the page or file, the browser's name and the time — for operating and securing the server. It is not joined to anything, not used for anything else and not shared. The server is a virtual machine rented from a hosting provider and administered by RAGTUX; there is no content-delivery network or third-party proxy in front of it.
Requests. To see, correct or delete what we hold about you, write to privacy@ragtux.com. There is very little to hold.
Contributions
Nothing is for sale. A contribution made through the Support lapstack link in the app or on the pricing page is a gift to the work, not a purchase: it buys nothing, issues no key and changes nothing in the app, and, since RAGTUX is a company, it is not a tax-deductible donation. Stripe sends the receipt. A contribution made by mistake is returned within fourteen days on request, no reason needed.
Third-party components and the raw decoder
lapstack is built from open-source components under permissive licenses, listed with their copyright notices in THIRD-PARTY.md, which also ships with every program.
One component is under the GNU Lesser General Public License, and lapstack is arranged so that you get what that license promises. Camera raw decoding is done by lapstack-raw, a module built on rawler (dnglab's library, copyright Daniel Vogelbacher, LGPL-2.1). lapstack does not link it: the command-line tool loads it as a shared library that sits next to the binary, and the browser app loads it as a separate module when the first raw file arrives. Its complete source, with the small change lapstack makes to rawler and a workspace file so it builds as it is, ships with every build as lapstack-raw-src.tar.gz. You may modify it, rebuild it and put your build in the old one's place, and lapstack will use yours; the README inside says how. The rest of lapstack is under the MIT license, and the two are kept apart so that each license's terms are plain and the module can be replaced, as the LGPL asks.
The fonts are Fira Sans and Fira Mono, under the SIL Open Font License.
Trademarks and names
"lapstack" and "RAGTUX" are names of RAGTUX LLC. Other companies' product names that appear on this site — Adobe Lightroom Classic; Zerene Stacker and Helicon Focus, which the manual names where lapstack follows a method they established; and the makers of the cameras whose raw files lapstack reads — belong to their owners, who have nothing to do with lapstack and have not endorsed it. The lapstack name may be used to refer to lapstack (a review, a forum post, a tutorial) but not to name another product or to imply endorsement.
The source
The source of lapstack is at github.com/ragtux/LAPSTACK under the MIT license, and every release's builds are published there. Earlier revisions were published for a few days in September 2026 under the GNU Affero General Public License, and then carried a proprietary license that was never attached to a sale; copies taken under either remain under those terms, and nothing since 9 October 2026 is under them.
Contact
RAGTUX LLC, Minnesota, USA. support@ragtux.com
for anything about lapstack; legal@ragtux.com for
the license and privacy@ragtux.com for your data,
if you prefer — all three reach the same person, so expect a reply from a
person, usually within a few days. A security problem in lapstack or on these
sites goes to security@ragtux.com
(/.well-known/security.txt says the same); please give us a reasonable time
to fix it before publishing.
Changes to this page
This page changes when the terms do, and the date of the last change is here: 9 October 2026 — lapstack is free software under the MIT license; the planned tiers, the key and the refund terms are gone, and the source is public. 1 October 2026 — the trademark notice names the stacking programs the manual refers to. First draft 30 September 2026.