ClipSpan : Universal Clipboard Sync

ClipSpan is a cross-platform clipboard history and sync system. Copy or select content on Android and paste it on a Linux or Windows desktop, and the other way around, with searchable history across devices. No root access or unsafe permission workarounds.

Status: v0.16.0. One Android APK (companion + ClipSpan Keyboard) and a Rust/Tauri desktop client for Linux and Windows, with first-run setup and signed auto-updates. Also includes a docked history picker, multimedia sync, offline-resilient history, encrypted vault backup/restore, Hidden / Recently removed with durable purge, and optional end-to-end encrypted account + relay. Approaching private/public testing. macOS planned.

Product site & testing: clipspan.com. Current product state and signup for private/public testing when builds open.

Overview

ClipSpan treats clipboard data as sensitive by default (passwords, tokens, addresses, code snippets). Local-only LAN pairing remains the default. Explicit user-controlled send/paste validates the protocol first; opt-in automatic sync and optional account/relay paths layer on after that.

Daily flows:

• Android Send Clip (selection action, share target, keyboard toolbar)
• Android Paste from history / desktop (keyboard toolbar, companion history)
• Desktop tray Send Clip, hotkey history picker, paste-into-focused-app
• Searchable cross-device history with hide, recently removed, undo, and clear controls

Install, pair, and daily paste should stay simple, with privacy and user control first.

Media

Desktop and Android histories staying in sync:

Desktop history picker docked at the top of the screen (hotkey paste into the focused app):

Architecture Highlights

Modular Layers

User interface layer
Clipboard access layer
Sync protocol layer
Transport layer
Storage/history layer
Pairing/security layer
Platform adapter layer

Each layer is decoupled so the Android keyboard, companion app, Linux/Windows desktop client, and future macOS client can evolve independently.

Android (Gradle Multi-Module)

• Ships as one APK (com.clipspan.app): companion Connect/history/account UI is the launcher; ClipSpan Keyboard is included in the same package
• sync-core/ : HTTP clients, protocol, Room history, sync coordinator, account client
• sync-ime-bridge/ : fork-agnostic IME toolbar (push/pull/history, password guard)
• companion-app/ : Connect/QR pairing, history, settings, Account screen, share targets, first-run setup, Report a bug
• keyboard/ : FlorisBoard-based IME with toolbar + history grid (Floris clipboard history and addons store hidden)
• Shared history via HistoryContentProvider so companion and keyboard use one Room DB

Desktop (Rust + Tauri 2 + Svelte)

• Shared Linux/Windows client: clipspan-core (axum HTTP hub, SQLite, QR pairing, mDNS), clipspan-clipboard adapters, Tauri tray UI
• Docked history picker (edge bar, opacity, hotkey toggle); paste selected item into the focused app
• First-run setup wizard (skippable); Linux clipboard/paste tool check with the distro install command
• Signed desktop auto-updater (GitHub releases); single-instance guard; Settings About; Report a bug / Copy diagnostics (no clipboard content or secrets)
• Native in-process X11/XWayland clipboard watching; Wayland falls back to wl-paste / watch; Windows clipboard adapters
• Headless clipspan-daemon still available for CI or no-GUI hosts (legacy Python FastAPI daemon superseded for daily use)

Account + Relay (optional, self-hostable)

• Rust/Axum account-api + relay with PostgreSQL path; email/password MVP
• End-to-end credential vault and opaque relay mailbox/blobs (HPKE-sealed payloads; servers store ciphertext)
• Trusted-device sliding sessions, device rename/revoke/unrevoke, encrypted history vault backup/restore, soft-delete with delayed hard purge

Offline-Resilient History

• Merge-only history sync: local Room / SQLite cache never wiped when peers are unreachable
• Offline paste fallback, local image capture, pending push flush on reconnect
• Per-device hide registry, recently removed retention, and vault plaintext that preserves hidden state across restore

Key Features

Tech Stack

• Android: Kotlin · Gradle · Room · CameraX · ML Kit · FlorisBoard fork · OkHttp · Rust (native keyboard lib)
• Desktop: Rust · Tauri 2 · Svelte · axum · SQLite · wl-clipboard / xclip / native X11 backend
• Server (optional): Rust · Axum · PostgreSQL · HPKE / Argon2id / ChaCha20-Poly1305 vault crypto
• Protocol: Versioned JSON schemas (pair_bootstrap, device_credential.v1, CLIPBOARD_PUSH / LATEST, vault plaintext v1–v3)
• Tooling: pytest · cargo test · ADR-documented phases · CHANGELOG-driven version sync

Highlights

• User-visible control first: manual Send Clip / Paste validates the protocol before automatic sync.
• Local-first by default; account and relay are opt-in and end-to-end encrypted on the cloud path.
• One Android install: companion UI and ClipSpan Keyboard ship in a single APK.
• First-run wizards and signed desktop updates so a tester can install, pair, and stay current without a changelog tour.
• Docked desktop history picker and ClipSpan Keyboard keep history next to where you type or paste.
• Offline-resilient history and reconnect flush so copies made away from the hub still converge.

Repository

The application codebase is private. Public marketing site: clipspan.com (signup for private/public testing).

Portfolio case study: jeremyb.dev/projects/clipspan/

Skills Demonstrated

• Cross-platform system design (Android IME + Rust desktop + shared sync protocol)
• Android multi-module Gradle project with composite keyboard build (Kotlin + Rust NDK)
• Rust/Tauri desktop engineering (clipboard backends, Wayland shortcuts, docked overlay UX)
• Self-hostable account/relay services with E2E vault and device-bound sessions
• Offline-first sync semantics (merge-only reconcile, pending push flush, blob lifecycle)
• FlorisBoard fork maintenance and IME toolbar integration
• ADR-driven phased delivery through account sync, history UX, and frictionless first-run / updater packaging
• Privacy-first product defaults (local-only LAN, password-field guard, ciphertext-only relay)

Next Steps

• Private, then public testing via the clipspan.com signup
• Store packaging (Windows Authenticode, Play listing / Android release signing)
• macOS client