Hotmetal

Edit AI-generated HTML documents visually. Open the slide deck, proposal or one-pager an AI agent wrote, click the words you want to change, and save clean HTML back to the same file.

What it does

• Edit text in place, and change colours, fonts, images and layout on a canvas, like Google Slides or Docs.
• Saves only what you changed: the rest of the file stays byte-for-byte identical, so diffs stay small.
• Understands slide decks (single files and folders of numbered slides), A4 and Letter paged documents, and flowing documents.
• Version history, crash recovery, and detection of changes made by agents while a file is open.
• Exports to PDF, PNG and self-contained HTML, and presents full screen.
• Runs locally. Nothing is uploaded; there are no accounts or telemetry.

Get Hotmetal

• Use it in your browser at hotmetal.app. It works on files on your own machine.
• Download the macOS app (Apple Silicon, macOS 13+) from GitHub releases.
• Or use the command line: hotmetal report.html.

Hotmetal is free and open source under the MIT license. Source code: github.com/mattfalconer/hotmetal. Information for AI agents: llms.txt.