Privacy Policy

FlowViz is built around a simple idea: your diagrams are yours. This page explains exactly what data the site and the FlowViz browser extension touch, in plain language.

Your diagrams stay in your browser

Diagrams you write in the editor are stored in your browser's localStorage on your own device. Writing, rendering and exporting all happen locally — nothing is uploaded, synced, or transmitted to our servers or anyone else's while you work. There are no accounts, so there is nothing to log into. Clearing your browser data deletes your diagrams, and we could not recover them for you even if you asked, because we never had them. The one way a diagram reaches our servers is if you create a short link, which is described next.

Two kinds of share link, and only one is stored

A share link compresses the diagram source into the URL itself. The diagram is not stored on our servers — it travels entirely inside the link.

A short link works differently. To keep the URL short, the diagram source is uploaded to our storage under a random eight-character id, and the link redirects through it. This happens only for diagrams you deliberately short-link, and only at the moment you press that button.

Stored diagrams are deleted 3 months after they are created, by a job that runs every day. After that the short link stops working and the copy is gone from our storage. If you need a link that lasts, use a share link instead — it holds the diagram in the URL, so there is nothing on our side to expire.

With either kind of link, anyone who has it can view the diagram. Treat a share link the way you would treat the diagram itself.

Anonymous usage analytics

We use Google Analytics to understand aggregate usage — which pages are visited and which features are used. Google Analytics sets its own cookies and processes data under Google's privacy policy. We also log page views to our own server as a fallback: each entry records the page path, referrer, browser language, and country/region (derived from our hosting provider's geolocation headers). These first-party logs contain no cookies, no IP addresses, and no identifiers that could tie a visit to you. Diagram content is never included in any analytics.

Email, only if you ask

If you enter your email address to receive the cheatsheet PDF or updates, we store that address with our email delivery provider (Resend) and use it only to send you what you asked for. Every email includes an unsubscribe link, and unsubscribing removes your address. We never sell or share email addresses.

Removing your data

The only personal data FlowViz can hold is an email address you chose to submit. Every email we send includes an unsubscribe link, and unsubscribing removes your address from our provider. Everything else — your diagrams, your settings — lives in your own browser, where clearing site data removes it completely.

The browser extension

If you use the Mermaid Diagram Viewer extension for Chrome, this section covers it. The short version: the extension collects nothing. It has no analytics, no accounts and no tracking, and it makes no network requests of its own — not even to FlowViz. Mermaid, the library that draws the diagrams, is bundled inside the extension, so diagrams are drawn on your own device. The analytics and email sections above are about this website and do not apply to the extension.

What it reads. The extension only looks at a page in three cases: on the AI chat sites it works with from install (ChatGPT at chatgpt.com and chat.openai.com, Gemini at gemini.google.com, DeepSeek at chat.deepseek.com, and Doubao at www.doubao.com); on a page where you ask it to, by clicking its icon, pressing its shortcut or using its right-click menu, which gives it that one tab until you navigate away; and on sites where you chose "Always render", each of which Chrome asks you to approve separately. On those pages it looks for Mermaid code and draws the diagram next to it. It does not collect, store or send what it reads.

What leaves your device. Only one thing, and only when you click it: "Open in FlowViz" opens this website's editor with the diagram compressed into the part of the link after the #. Browsers never send that part to a server, so the diagram reaches the editor in your browser but not our servers. The rest of the link says only that you came from the extension and which theme you picked. Opening the editor is an ordinary visit to this website, covered by the analytics section above. Copying and downloading diagrams happen on your device.

What it stores. Your extension settings — whether diagrams render automatically, your theme, and the sites you chose to always render on — are kept in Chrome's extension storage. If you use Chrome sync, Chrome syncs them through your Google account like any other extension's settings. Sites you answered "Not now" for are remembered until you close the browser. Nothing about the pages you visit or the diagrams you view is stored. Removing a site in the extension's menu also gives its permission back to Chrome, and uninstalling the extension removes everything.