Intelligent label printing

➜ Install from the Chrome Web Store · Download the helper · Support on Ko-fi

A Chrome extension that prints courier labels in one click. The label in the PDF can fill a whole A6 page or sit on a quarter of an A4 page. Either way, the extension:

1. renders each PDF page and detects its content (the label),
2. crops the white margins. In automatic mode it also skips small text next to the label and splits several labels on one A4 page into separate labels,
3. builds a new PDF that fits the paper loaded in the printer of the selected profile,
4. sends it straight to that printer through a small helper program, with no print dialog (macOS: CUPS lp; Windows: the printer driver).

Paper in the profile	Result
A4	the label in an A6 area (105×148 mm) in the chosen corner of the sheet, with cut lines; optionally 2 or 4 labels per sheet
A6 / 100×150 / 4×6" / custom	the label scaled and rotated to fill the whole page

Free and open source, forever. No subscription, no trial, no account, no paid tier: every feature is free for everyone. Labels are processed only on your computer and never uploaded anywhere (see the privacy policy).

The extension starts in your browser's language if it has a translation (currently English and Polish), otherwise in English. Switch it any time in the popup or under Settings → Language. A short user guide is available in English and Polish. The Help link in the settings opens it in the chosen language.

Installation

1. Print helper (once)

Chrome does not let extensions print to a chosen printer without showing a dialog, so the extension uses a small helper program. The extension's settings page detects when the helper is missing or outdated and shows the right download button.

macOS: download and open LabelPrintingHelper-macOS.pkg.

• The installer is not signed yet. If macOS says the developer cannot be verified, open System Settings → Privacy & Security and click Open Anyway.
• The helper is installed in /Library/Application Support/IntelligentLabelPrinting/ and registered with Chrome, Edge, Brave and Chromium.
• To uninstall, run: sudo "/Library/Application Support/IntelligentLabelPrinting/ilp-host" uninstall --system.

Windows: download LabelPrintingHelper-Windows-x64.exe (or -arm64.exe for Windows on ARM) and double-click it.

• It copies itself to %LOCALAPPDATA%\IntelligentLabelPrinting and registers with Chrome, Edge, Brave, Chromium and Vivaldi. No administrator rights are needed.
• The file is not signed yet. If SmartScreen appears, click More info → Run anyway.
• To uninstall, run: "%LOCALAPPDATA%\IntelligentLabelPrinting\ilp-host.exe" uninstall.
• Windows has no built-in PDF printing, so the extension renders each label at the printer's own resolution and the helper prints it through the driver with the exact paper size. Custom sizes work as well: forms created in Print server properties appear at the top of the media list.

Developer install (macOS, no admin rights):

bash ~/Labelprinter/helper/build.sh

~/Labelprinter/dist/ilp-host-macos install

2. The extension

Install it from the Chrome Web Store, then pin the icon to the toolbar. It also works in Edge, Brave and other Chromium browsers.

Without the store (development or testing):

1. Open chrome://extensions and turn on Developer mode.
2. Click Load unpacked and select the extension folder of the project, or the unzipped extension-unpacked.zip from the release. Don't use the Chrome Web Store zip: it gets a different ID.
3. Both ways give the same extension ID, fcfpnegfonhlplflgmjapjgkdcpdfkma, which matches the helper. Keep only one copy installed at a time.

3. Profiles

In the extension settings, assign a printer to each profile (the list comes from the system) and pick the media size in the driver.

The extension reads every media size's real dimensions and non-printable edges from the printer driver:

• The paper size follows the media size. It is shown as a read-only line (e.g. Paper: 102 × 152 mm – taken from the media size above), so the paper and the driver media can't get out of sync. A4 media switches to the cut-to-A6 layout.
• You set the paper by hand only when there is nothing to derive it from: the profile has no printer, the media size is unknown, or you chose Custom size = paper set below, in which case that size is sent to the printer.
• The non-printable edges are applied automatically, so nothing gets clipped.

Custom paper sizes

• macOS custom sizes. Sizes you created in the macOS print dialog (Paper size → Manage Custom Sizes…) appear at the top of the media list.
• Last used size. The size you last used for a printer in the macOS dialog is marked with ★. It is also selected automatically when you pick that printer.
• Custom size = paper set below. This option sends the profile's paper size to the printer as a custom size, e.g. Custom.102x152mm.

Many label printers, the Brother QL among them, print reliably only with the custom size you already use in the system dialog. If a predefined size makes the printer blink red, choose your custom size.

Brother QL (e.g. QL-1100 / QL-1110NWB)

• Die-cut 102×152 mm labels (DK-11241): choose 102 mm x 152 mm · DC16.
• Continuous tape: avoid 102mm, 102mmx2, 102mmx3 and similar. These are continuous-tape sizes with a 100 mm tall landscape page (102mmx3 is about 299×100 mm). With 4×6" labels, the driver will scale, rotate and cut the label into several pieces.

Thermal printers (e.g. ITPP130, Zebra)

• Choose the size that matches your labels, e.g. w288h432 for 4×6".

Usage

• Popup: choose a profile, then click Print PDF from this tab, or click Print next to one of the recently downloaded PDFs.
• Right-click a PDF link or a page: Intelligent label printing → Print: .
• Shortcut Alt+Shift+P: prints the PDF in the current tab with the active profile.
• Automatic printing (optional): PDFs downloaded from the listed domains print by themselves.
• Preview: shows the cropping result (sizes, scale, rotation) and lets you compare profiles before printing.

Printing a shipping code or any text

Some services give you a short code instead of a label. Turn on Settings → Shipping code label and the popup gets a field: paste the code and press Enter. You can also select the code on a page and right-click → Print as code.

• Graphic code: QR code, Code 128 barcode or none. It contains exactly the text you entered.
• Optional extras: a header (default "Shipping code"), the date and time, and a daily sequence number (#1, #2… from the first code each day).
• Label printers: the code fills the whole label. With a long roll of continuous tape, turn on Advanced → print only as much as the content needs in the printer profile; the label is then only as long as needed (at least the minimum length you set).
• A4 printers: the code is printed in an A7 area (74×105 mm) to cut out, in the corner chosen for the A6 area.

Moving settings to another computer

In Settings → Backup & transfer, click Export to file to save all profiles and settings as a JSON file. On the other computer, click Import from file… and choose one of two options:

• Replace all settings: the file becomes the full configuration.
• Add / update profiles: profiles with the same name or ID are updated and the rest are added.

Printer names are matched ignoring punctuation, so Brother_QL_1110NWB (macOS) matches Brother QL-1110NWB (Windows). For any printer that isn't found, the page lists the profiles that need a printer chosen.

Troubleshooting

• The printer blinks red and does not print. The media size in the job does not match the loaded roll. Select the custom size you normally use in the macOS print dialog (marked ★).
• The label comes out in several pieces, or rotated and enlarged. The selected media doesn't match the labels loaded in the printer, e.g. continuous tape instead of die-cut labels. Choose the media that matches your roll. The settings page warns when the media is continuous tape.
• The edges are clipped. Increase Margin inside the label area, or set Printer-side scaling to Fit to page.
• "No print helper". The settings page shows Chrome's exact error and a hint:
  • not found: the helper isn't registered. Run the installer again and close Chrome completely before reopening it.
  • forbidden: the extension has a different ID than the helper expects. Load extension-unpacked.zip, or allow the ID with the command shown on the page (ilp-host install --extension-id <ID>).
  • exited / failed to start: the helper was blocked or crashed. Check your antivirus.
• Check the helper registration: on Windows, double-click the helper again, or run ilp-host status (macOS: "/Library/Application Support/IntelligentLabelPrinting/ilp-host" status --system).
• Windows: wrong size or blank page. Choose the matching paper in Media size in the driver. Many label printer drivers on Windows only accept their own paper sizes or a form created in Print server properties.

Project structure

extension/        Chrome extension (Manifest V3)
  engine.js       content detection and PDF composition (pdf.js + pdf-lib)
  background.js   fetching PDFs, context menu, printing through the helper
  i18n.js         loads the chosen language from _locales (English fallback, plural rules)
  popup.*, options.*, print.*   user interface
  _locales/       all texts, one messages.json per language (also the store name and description)
  languages.json  the languages offered in the language menu
  config.js       project links: helper downloads, donation pages, minimum helper version
helper/           Native Messaging helper in Go (one binary, no dependencies)
  print_cups.go   macOS / Linux printing (CUPS)
  print_windows.go  Windows printing (winspool + GDI)
  install_*.go    self-registration with the browsers
  build.sh        builds everything into dist/
keys/             the extension's private key – keep it safe, never publish it
docs/guide/       short user guide, one file per language
scripts/          check-i18n.mjs – translation check (also runs on Pull Requests)
test-pdfs/        sample labels for testing

Requirements: Chrome 120 or newer (or Edge, Brave), on macOS 11+, Windows 10/11 or Linux with CUPS.

Building and releasing

Install Go once (e.g. brew install go), then build everything:

bash helper/build.sh

The build writes these files to dist/:

File	Purpose
LabelPrintingHelper-macOS.pkg	macOS installer (Intel + Apple Silicon)
LabelPrintingHelper-Windows-x64.exe	Windows helper
LabelPrintingHelper-Windows-arm64.exe	Windows helper for ARM
extension-unpacked.zip	the extension for Load unpacked. It keeps the extension ID the helper expects.
extension-chrome-web-store.zip	package for Chrome Web Store updates. It is built locally and not attached to GitHub releases. Don't load it unpacked: without the key, Chrome gives it a different ID and the helper refuses it.
extension-webstore-first-upload.zip	package for the first Web Store upload. It contains key.pem, so the store keeps the same extension ID the helper expects. Never share it.

Release checklist:

1. Bump Version in helper/main.go, MIN_HELPER_VERSION in extension/config.js (if the extension needs the new helper), and version in extension/manifest.json.
2. Run helper/build.sh.
3. Upload the installers to a GitHub release. The download buttons in the settings point to releases/latest/download/<file name>, which is set in extension/config.js.
4. Upload extension-chrome-web-store.zip to the Chrome Web Store.

Donations

The ☕ Support the project button in the settings opens the page set in extension/config.js:

• donate: e.g. Ko-fi;
• donatePl: e.g. buycoffee.to, used when the UI is in Polish.

The button is hidden while both are empty.

Translations

Help translate the extension into your language. It's one file per language, and you don't need to know JavaScript. See TRANSLATING.md. Every Pull Request that touches translations is checked automatically. Missing texts show in English until they are translated.

Support

If the extension saves you time, you can support it on Ko-fi. Donations go towards code-signing certificates, so the helper installs without security warnings on macOS and Windows.

License

MIT – see LICENSE. pdf.js (Apache 2.0) and pdf-lib (MIT) keep their own licenses.