Check the HTML of your email
Mail clients render a small, old subset of HTML, and each one differently. This shows you the parts that will not survive the trip — before you find out from a colleague.
- Runs entirely in your browser
- Works offline
- No upload
- No sign-up
- No watermark
Loading the tool…
How it works
- Paste the HTML of the message — from your newsletter tool’s source view, or the file you are about to send.
- Read the findings, then the links and images tables.
- Use the preview to check the narrow widths, dark mode and, above all, what it looks like with images blocked.
Why nothing is uploaded
Every operation on this page is done by code running inside your browser tab, using the same engine that renders web pages. The file is read from disk into your tab’s memory, transformed there, and written back out as a download. It is never sent anywhere — not to us, not to a third party.
Verify it yourself
- Open your browser’s developer tools (F12) and select the Network tab.
- Load your file and run the tool.
- The only requests you will see fetch the tool’s own code — and, for a few heavy tools, their open-source engine from a public CDN — plus one small page-view ping to loreatec.jp (page address and title, nothing more). None of them carry your file.
Frequently asked questions
Why is my <style> block a problem?
Gmail keeps most of it, Outlook on Windows keeps some, several webmail clients strip it entirely, and none of them fetch an external stylesheet. Anything that must be right has to be an inline style attribute; a <style> block is for the media queries that cannot be inlined at all. The CSS inliner on this site does the mechanical part.
What is the 102 KB limit?
Gmail stops rendering a message at about 102 KB and shows a “View entire message” link. Everything after the cut is hidden — usually the footer, which is where the unsubscribe link and the postal address live. That makes it a compliance problem as well as a design one. Trim the HTML, not the content: most of the weight is repeated inline styles and table scaffolding.
Why does it not tell me whether my links work?
Because a browser cannot read a response from another domain — the same-origin policy forbids it, and no amount of cleverness gets around it without a server relaying the request. The links are listed instead so you can check them; a checker that “verifies” links either has a server or is guessing.
What does the images-blocked view show?
What most recipients see first. Gmail, Outlook and Apple Mail all block remote images by default in at least some situations, and a design that is one big image becomes an empty rectangle. If your message is unreadable in that view, it is unreadable for a large share of your list.