Open-source CLI tool lets developers preview and debug thermal receipts without a printer

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ESCPost, an open-source Rust command-line tool released under the Apache-2.0 license, allows developers to render and debug ESC/POS thermal printer receipts entirely on their local machine without needing physical hardware. The tool converts raw ESC/POS byte sequences into PNG images at the printer's actual dot resolution, cutting a typical test cycle from around 90 seconds to roughly 3 seconds. It also includes a TCP server mode that intercepts print jobs sent over port 9100 from third-party software such as ERP or POS systems, displaying decoded commands and byte-level details in a browser interface. Developers can identify common issues like incorrect code pages causing garbled currency symbols by inspecting the exact byte and its associated printer state. The tool supports multiple printer profiles to account for real-world differences in printable width, DPI, and character sets, and is available to install via Homebrew.

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