Android / Windows / Linux

PrintR

Local-network printing from an Android phone through a desktop agent, built by John Finnerty in Christchurch, New Zealand.

Status: in-development project with public source and test builds. This note covers the 1.1 development work, not a production support offering.

Evidence reviewed 20 September 2026.

Review the evidence Public repository Application screenshots

The workflow

From phone to the computer's print queue

PrintR lets the phone choose a document and send it to a paired computer on the local network. The Android app handles file selection, computer pairing and print options. A .NET agent manages conversion, the job queue and the operating system's printing backend.

Pair the Android app with the Windows or Linux agent using its connection details.
Select a document and a printer reported by that computer.
Upload over pinned HTTPS, then follow the job's status in the app.
The desktop backend submits the job to the operating system's print queue. Physical output still depends on the printer and driver.

Evidence and scope

What has been checked

Public automated checks

The 20 September verification run passed its Windows, Linux and Android jobs at commit ded072d. The workflow covers agent tests and packaging, Windows/Linux HTTPS smoke checks plus Android unit tests, debug build and lint.

Recorded local validation

The versioned validation record reports 61 Windows tests, 31 Linux/shared tests on Windows and 15 Android tests per build variant. It also records real conversion of seven document formats on Windows and Linux. These are maintainer-recorded results, distinct from the public CI run.

End-to-end mock workflow

The documented Android emulator session paired with the Windows agent over pinned HTTPS, listed printers and uploaded an XLSX file to a completed mock job. The captures below show that session. Mock completion did not send paper to a printer.

Physical printer check

I have also tested PrintR and confirmed that it works on my own printer, reported on 20 September 2026. This is my own hands-on confirmation, separate from the mock-mode captures. It is not a compatibility claim for other printers, formats or driver options.

Real application captures

Windows dashboard and Android workflow

Captured on 20 September 2026 from the Windows application and Android API 35 emulator. These images are unchanged copies from the versioned screenshot record. Click an image for its full-size view.

PrintR Windows Overview with mock printing enabled, converter readiness and installed printers — Windows Overview: setup readiness and printer enumeration. Mock printing is explicitly enabled.

PrintR Windows Settings showing saved options, mock mode and complete action-button borders — Windows Settings after the layout fix: persistent options and complete action-button borders.

PrintR Android emulator with a selected XLSX file, paired connection and enumerated printers — Android file selection and printers returned by the paired Windows agent.

PrintR Android completed job with the visible warning that mock mode did not send it to a printer — Completed mock job, with the no-paper warning visible. This is not the separate physical-printer test.

Engineering decisions

Make pairing, job state and limits visible

Discovery finds a computer but does not authorise printing. New pairings use a token and pin the agent certificate fingerprint. The desktop dashboard separates setup readiness from recent jobs, while Android distinguishes backend completion from mock-mode acceptance.

The Settings layout now sizes rows to their content so action and Browse button borders remain visible. The validation record includes five layout regression cases. This is a small usability fix with an inspectable before-and-after record.

Uploads have format and size checks, and converted documents use separate job folders. These controls are not a complete sandbox for hostile documents. The security notes explain the trust boundary, retention and local-network-only intent.