What to know before you paste an iframe
Framing is one of the few parts of the web where the failure is completely silent, so the questions here are mostly about telling a working embed from one that only looks like it works.
The short version
The page being framed decides whether it can be framed, a blocked frame still fires load, an iframe cannot read the page around it, and every entry here was probed before it was listed.
Questions
How do I embed one of these?
Copy the snippet from the page for the thing you want. It is an ordinary iframe with the sandbox attributes already set, so it works in any HTML — a static site, a CMS block, a docs page, a Notion embed. Nothing needs an account and nothing needs a script tag.
Will the embed actually load, or will it be blocked?
Every entry here was probed before it was listed: the page had to answer 2xx, its X-Frame-Options and CSP had to permit framing, and the title it served had to match the one we list. 847 candidates failed one of those and are not in the catalogue.
Why does a page that loads fine sometimes refuse to embed?
Because framing is decided by the page being framed, not by the page framing it. A site sends X-Frame-Options or a CSP frame-ancestors rule and the browser enforces it. The frustrating part is that a blocked frame still fires a load event, so from the outside a refused embed looks exactly like a working one — which is why the check happens when the catalogue is built rather than when you paste the snippet.
Is it safe to embed something from another site?
An iframe is a separate document with its own origin, so it cannot read your page, your cookies or your storage. What it can do is navigate, open windows and take the space you give it — which is why every snippet here carries a sandbox attribute limiting it to running scripts, and why none of them is granted same-origin access.
Do these belong to Leumas?
No, and the catalogue says so on every entry. These are public pages other people publish, listed with the provider named and linked. We verified they can be framed and we describe what they are; we do not host them, we cannot change them, and if one goes away the entry goes with it.
What happens if an embed disappears?
The catalogue is regenerated by re-probing every URL, so an entry that stops answering, stops permitting frames or starts serving something else is dropped rather than left as a dead card. That is also why each entry shows when it was last verified.
Can I write my own and get an embed URL?
That is the half of this site still being built. When it lands, an app you write is served from its own origin in a sandbox with no same-origin access — because a page that runs other people's JavaScript on its own origin is a page that can read the session cookie of everyone who opens it.
Do you track people through the embeds?
We count how many times an embed is served, because that is the number a quota is based on. We do not set cookies in an embed and we do not build a profile of the people who see one. What the embedded page itself does is between it and its own visitors, and it is a third-party page.