Cairn is a release-gate we built and run ourselves — it stops an engineered-to-order manufacturing shop from ever building the wrong version of an approved design. An engineer locks an approved set of drawings and files, the customer signs off from a single no-login link, and the moment anything in that set changes the approval voids itself and production is blocked. It's provisioned per shop and invite-only, not self-serve. Talk to us about Cairn →
In control-panel and machine building, the expensive mistakes aren't bugs — they're a shop cutting metal against revision C while the customer already signed off on revision D. Approvals live in email threads and shared drives where the file behind the sign-off can quietly change and nobody notices until it's built. We set out to make an approval something you can trust: tied to an exact set of files, impossible to silently alter, and provable months later in an audit.
Every approval is bound to a cryptographic hash of the exact files it covers. Swap, edit or re-export any of them and the lock no longer matches — there is no such thing as an approval that quietly drifted off the files it was for.
The customer approves from a single signed link — no account, no password, no friction — while every action is still attributed and recorded. Getting sign-off stops being the bottleneck.
A post-approval file change doesn't just warn — it voids the approval and gates the release, so a superseded revision physically can't be pushed to the floor. The gate is enforced on the backend, never trusted to the UI.
Each approval produces a PDF record, an append-only audit history, and a public verification page that reports a given release as valid, void, withdrawn, superseded or tampered — the paperwork a dispute or a certification body actually asks for.
Cairn is compliance-grade B2B SaaS end to end — multi-tenant, role-aware, signed and audited — the kind of build where a mistake is a customer's, not a toy. It's in production and provisioned by invitation for control-panel and machine builders. If you're a shop that lives or dies on building the right revision, or a business that needs an approval you can prove, tell us about it.
Send what you have. You get a scoped plan and one fixed number within a business day.
We build software worth keeping — for clients, and for ourselves.
Founded & led by codewithumar