LaBLEr

LaBLEr is an open-source Android app for designing and printing labels with Marklife-family Bluetooth Low Energy thermal printers, including the P15, P12, and L13. It lets users create labels on a phone, save their designs as templates, and print them again without an account, cloud service, or vendor app. Only the P15 has been verified on-device so far, while the P12 and L13 use the same protocol and a 12 mm, 96-dot print head.

The editor supports multi-line text with sizing, bold, italic, underline, alignment, bundled fonts, and imported TTF or OTF files. Labels can also contain symbols, emoji, frames, imported images, and QR codes or barcodes including Code 128, EAN-13, UPC-A, Code 39, and ITF. QR content can be entered for links, Wi-Fi details, email, phone numbers, and contacts. Elements can be moved, resized, rotated, zoomed, and panned directly on the canvas, with snapping to the center, edges, and other elements.

Graphics are prepared for the printer’s 1-bit thermal head using outline rendering with region tracing or Canny edge detection, a smooth pass and invert option, or threshold, Floyd-Steinberg, and Atkinson dithering. Users can save, rename, duplicate, favorite, and search templates, export an individual label as JSON, or back up and restore the complete template library. Date, time, running-number, and free-text placeholders can be filled in at print time. LaBLEr also provides an exact 1-bit preview, copy selection, die-cut or continuous media options, reproducible print history, and automatic reconnection to a saved printer.

As an Android application in the Internet & Browsers category, LaBLEr is designed around direct local communication over Bluetooth Low Energy. It does not declare the INTERNET permission, so its process cannot open a network connection, and its templates, print history, and settings remain in the app’s private device storage without analytics or tracking. The interface uses Material 3, follows the system’s light or dark setting, and is available in 17 languages. MirrorNest distributes the official Android build directly from its own storage and scans it for malware before publishing.