Dev server

formfeed dev invoice-de
# formfeed dev: invoice-de on http://127.0.0.1:4400

Run it inside a project. Without a slug it opens the first template in alphabetical order. Stop it with Ctrl+C.

• Watches the template's folder, the partials and files folders and .formfeed/ and re-renders on every change; the browser updates over server-sent events. Running formfeed brand pull in another terminal updates the preview too.
• Paged (the default) shows real pages with headers, footers and page numbers, laid out by Paged.js as in the web editor; Flow shows the document as one long page. An image template is always shown in flow, at its pixel size.
• Switch data sets (data/*.json) and locales (i18n.json) from the toolbar.
• Diagnostics panel with the same messages as the web editor (line and column of each finding).
• Serves the project's files/ folder, so asset('logo.png') and relative image paths show the local copy of the file library. formfeed files pull fills the folder from the workspace.
• Templates see the brand kit of .formfeed/brand.json as brand; without the file they see an empty kit. formfeed brand pull writes it.
• True render button when a key is configured (--api-key, FORMFEED_API_KEY or the key formfeed login stored): the PDF or image the API produces from your local files with the selected data set. The panel shows the page count, the units it cost and a link to the file. A test key renders for free; the key formfeed login stores is a live key, whose renders count against your plan. Without a key the button is off and everything else works.
• For a template that declares pdf.ua, the preview checks the page it shows and lists what it found under Template check · PDF/UA-1, and a true render shows the validator's verdict with the rules that failed.

Word and PowerPoint templates

formfeed dev also opens a folder with template.docx or template.pptx. There is no local preview of the document itself:

• Edit the file in Word or PowerPoint and save it; the diagnostics panel lists the findings of the tags on every save, by part and paragraph (word/document.xml ¶12) instead of line and column.
• True render fills the document on your machine with the engine the render servers use and converts it to PDF through the API (POST /pdf/convert), which needs the Starter plan or above. The frame shows that PDF, and after the first true render every saved change renders again.
• QR codes, barcodes and SVG pictures are drawn by @resvg/resvg-js, an optional dependency of the CLI. Without it, and for WebP, GIF and AVIF pictures, which only the render servers draw, the render lists a warning and leaves the picture out.

Flags

Flag	Meaning
--port <n>	Port, default 4400
--host <host>	Bind address, default 127.0.0.1
--open	Open the browser
--data <name>	Initial data set (data/<name>.json)
--locale <tag>	Initial locale (from i18n.json)

Not available yet: --open-in-editor (vscode:// links in diagnostics) and --local-chromium (approximate render with a local Playwright Chromium).

The server binds to 127.0.0.1 by default, so only your own machine reaches it; --host 0.0.0.0 opens it to your network. A port that is in use stops the command with exit code 2; pick another with --port. It needs no account for the offline features.