Clipboard History Manager Desktop App

Every computer user copies dozens of items a day and loses nearly all of them — the operating system keeps only the most recent one, so a snippet copied an hour ago is gone the moment something else is copied. Developers, writers and students feel this constantly: a terminal command, a code block, a reference link, all re-typed or re-found from scratch. A clipboard history manager solves it by listening to OS clipboard events, storing each entry with its type, source application and timestamp, and surfacing the whole history through instant search and a global hotkey. This project implements that as a real desktop application: a system-tray resident program with a searchable history window, pinning, favorites, per-type filters and AES-256 encrypted storage, plus an optional end-to-end encrypted sync channel so the clipboard follows the student across machines.

1. On launch, the app registers OS clipboard listeners (Win32 clipboard viewer chain on Windows, NSPasteboard polling on macOS, X11 selections on Linux).
2. Each clipboard change is captured with metadata: content type, source application, timestamp and size, then written to the encrypted SQLite store.
3. The FTS5 index updates incrementally so search stays instant even with tens of thousands of entries.
4. Pressing the global hotkey summons the overlay window; typing filters the history live and double-click (or Enter) pastes the chosen entry via simulated keystrokes.
5. Pinned and favorite items are excluded from the retention sweeper, which deletes unpinned entries older than the configured window.
6. When sync is enabled, new entries are encrypted with the device key and pushed to the sync relay; other devices pull, decrypt and merge them by timestamp.

Tech stack:

• Python 3
• PyQt6 · Qt (desktop UI)
• SQLite · FTS5 (indexed storage)
• cryptography · Argon2id (encryption)
• pynput (hotkeys & paste simulation)
• PyInstaller (packaging)

• [System-wide clipboard monitoring] A background listener captures text, code, links and images from any application the moment they are copied, with negligible CPU overhead.
• [Instant full-text search] Every entry is indexed in SQLite with FTS5, so searching thousands of items returns results as you type.
• [Pinning and favorites] Frequently reused snippets can be pinned to the top or starred, surviving retention cleanup and staying one hotkey away.
• [Global hotkey paste] Pressing Ctrl+Shift+V anywhere opens the history overlay; double-clicking an entry pastes it into the active window.
• [AES-256 encrypted storage] The local database is encrypted at rest with a key derived via Argon2id, so copied passwords and tokens stay protected.
• [Cross-device sync] An optional sync service replicates the clipboard over an encrypted channel, with conflict handling when two devices copy simultaneously.
• [Per-type filters and retention] Separate views for text, code, links and images, plus configurable retention (7–90 days) with automatic cleanup of unpinned items.

• Complete desktop application source code
• Installers for Windows, macOS and Linux
• User manual (features, hotkeys, settings)
• Project report PDF (clipboard internals, storage and encryption design, sync protocol)
• PPT presentation for final review
• Viva Q&A preparation document (OS clipboard APIs, FTS indexing, Argon2id, E2E sync)

• Clipboard formats beyond text/HTML/image (e.g. proprietary app objects) are stored as plain text fallbacks.
• Sync needs both devices online at least once; there is no real-time push when a device is offline.
• Very large copied images (above ~25 MB) are stored as thumbnails with a size note to bound database growth.
• Paste simulation can be blocked by elevated/admin windows on Windows — a documented OS restriction, not an app bug.
• The macOS build needs accessibility permission granted manually on first run.
• Password-manager "clear clipboard after N seconds" behavior is respected and such entries are never stored.