HTML & Markdown Viewer

View .html and .md attachments from Gmail, Google Chat, Slack, Teams & Zalo in one click — Mermaid diagrams included.

AI tools like ChatGPT, Claude and Gemini hand you reports, specs and notes as .html and .md files, and your chat or inbox shows them as raw code. Click Preview and read each one as the page it was meant to be. • One click, right where the file arrives: Gmail, Google Chat, Slack, Microsoft Teams, Zalo, or any site you turn on • HTML works as built: charts, tabs and scripts run, CDN libraries included • Markdown looks like GitHub, with Mermaid diagrams drawn for you • Spot a mistake? Edit the Markdown, then save it or copy it back into your email • Also: right-click any .html or .md link, or open the toolbar button to drop a file or paste code • Source view, phone and tablet widths, save as PDF PRIVATE BY DESIGN TeamCook never uploads your files: they open on your device, in a sandbox. No server, no account, no analytics. Safe mode turns off a file's scripts, and IT admins can turn it on by policy. Release notes: 1.3.1 Google Chat preview fixed, no surprise downloads, editor and diagram fixes 1.3.0 20 interface languages, Arabic right to left 1.2.0 Markdown editor: visual and source editing, save, drafts 1.1.0 Renamed HTML & Markdown Viewer · Markdown preview · Mermaid diagrams · simpler viewer · lighter on your computer 1.0.3 No more tabs opening after a reboot 1.0.2 Google Chat cards with no Download control 1.0.1 Google Chat file cards, button click area, better rule reports 1.0.0 First public release Not affiliated with the makers of any product named above, names only describe where it works.