DiagEZ: a diagram URL for the document

Mermaid solved one problem well. A diagram written as text can be versioned, diffed and reviewed like code. It left another problem in place: the places a diagram needs to appear do not all render Mermaid. A wiki page, a slide, an email, an issue tracker, a PDF handed to a client. The workaround is a screenshot, which works until the diagram changes and the image does not.

Text in, image URL out

DiagEZ turns Mermaid source into an SVG or PNG image served from a URL. Paste the source, or a Mermaid Live URL, into the web builder, choose a theme and layout options, and copy the resulting address. The source is encoded into the URL itself, so the same text and options always give the same URL, and the API docs describe the encoding, the cache behaviour and the error responses: the full URL is the cache key, and successful renders are served with long-lived cache headers. No editor account is needed. DiagEZ is owned by VMCSoft Digital and published and operated by ViWeb Technology.

This fits the workflow that already exists. The Mermaid text stays in the repository or notes where it was written. The document that cannot render it gets an image reference instead of a pasted screenshot. Use SVG where the host accepts vector images and PNG where a raster image is required. Whether a particular platform accepts remote images at all is something to check with that platform rather than assume.

The URL is an image, not a document

Two properties follow from how the URL is built, and both matter in daily use.

First, encoding is not encryption. The Mermaid text is Base64URL-encoded, which anyone can reverse, and image URLs are public and cached. Do not put secrets, private hostnames, customer details or confidential system layouts into a diagram rendered this way. The builder on the DiagEZ home page says it plainly: do not place secrets or private data in the diagram URL.

Second, a URL is tied to one version of the source. Changing the source or any option produces a different URL, and the old one continues to describe the old source. That keeps an embed pointing at the version you chose, but it also means there is no “latest version” behind an existing link. The image itself is still produced by the renderer, so a renderer update can draw the same source a little differently; the text, not the pixels, is what the URL fixes. When the diagram changes, generate the new URL and update each embed deliberately. Keeping the editable source next to the document keeps that step easy.

Where it stops

DiagEZ renders what the parser accepts within documented limits. Oversized payloads, unsupported diagram types, unparsable syntax and temporary renderer or rate limits each return a documented error, and cache-miss rendering can be throttled under load. Treat an embed as something you own: keep the Mermaid source available for editing, as the builder advises, so a diagram can be regenerated if a render fails or the output changes. The examples page shows known-good renders across diagram types and themes, and the product site remains the reference for current options.

The next time a diagram needs to go somewhere Mermaid does not render, keep the text, generate the URL and retire the screenshot.