Castor is the boundary between a website you built and a client who wants to help. Mark exactly what they can repaint — the words, a photo, one button’s colour — and nothing outside the line moves, no matter how hard they lean on it.
Free, self-hosted, AGPL-3.0. No subscription, no seat count.
client-site.example
Tape marks what’s locked. Peel one back — it still says no.
Most CMSes hand a client the whole dashboard and hope for the best. Castor hands them a page and a taped-off line. You decide which side of it each thing sits on.
This isn’t a screenshot — type in the page below and it edits like the real thing. Then change what’s permitted and reach for a colour it won’t let you have.
Click any highlighted text and type.
Same-day appointments, and a team that explains what it’s doing before it does it.
Book a visitYou
Build the site your way, or import one you've already built. Decide what's structural — and what a client may repaint.
Your client
They get a link and a password, click a headline, and type. No tickets, no invoice for fixing a typo.
Castor
Every change is checked against the boundary you set before it saves. Nothing outside the line moves — ever.
Tick exactly what each client may touch — text, images, links, colour, spacing. Any combination. Change it whenever.
Let a client recolour a heading with the real OS colour picker — or keep them to the swatches you chose. Their call, your limits.
Every edit lands in a private draft. Nothing goes live until someone presses Publish. No surprise changes on the real site.
Publishing snapshots the site. Going back to how it looked on Tuesday is one click — not a restore from a backup.
Drag a ZIP of an existing site onto the dashboard. It becomes editable, its own scripts still running, safely sandboxed.
⌘Z and ⇧⌘Z, without stealing the browser's own undo while your client is mid-sentence in a paragraph.
Edits sit in a draft until published. Each publish is kept forever, so undoing a bad week is one click.
The source is public and yours to run — for as many client sites as you like, at no cost. It’s open source (AGPL) — anything you build on it stays open too.
Node · Vercel · MongoDB Atlas — free tiers are plenty
Not sure it fits what you’re building, or stuck getting it running? Ask — you’ll get a real answer from the person who wrote it.