Key Center

A focused, local-first API key vault for Windows
一个专注、清爽的本地 API Key 保险箱

Changelog

---

Key Center does one thing: it gathers the API keys scattered across your apps, projects and terminals into one clean, encrypted local vault.

No account, no cloud sync, no installer, no background service. One portable executable, one encrypted local file, one master password. It does not try to be a full password manager — it does not store URLs or usernames, and it does not generate passwords. It just does name + multiple keys + notes + categories exceptionally well.

A small, local-first vault for API keys. No account, no cloud, no installer, no background service. One portable executable, one encrypted local file, one master password.

Contents

• Why Key Center
• Features
• Screenshots
• Quick start
• Keyboard shortcuts
• Data & security
• Portable layout
• Build from source
• FAQ
• License

Why Key Center

• Local-first — everything stays on your machine, encrypted at rest; the app itself makes no network requests, and GitHub links open in your system browser.
• Truly portable — a single KeyCenter.exe; no installation, no registry writes, no user-profile clutter.
• Multi-key entries — keep several keys for the same service or project in one entry and switch the default key anytime.
• Focused and complete — categories, search, sorting, copy, reveal/hide, plaintext export, auto-lock and window memory, all included.
• Native feel — a hand-crafted WinForms UI with dark/light/system themes, Acrylic backdrop, high-DPI and multi-monitor support.
• Buildable — plain C# / .NET Framework source with no NuGet and no third-party runtime dependencies.

Features

One entry, many keys

• Each entry can hold any number of keys — ideal for multiple projects, environments or accounts of the same provider.
• The list shows only the default key (masked), and the copy button copies it.
• Every key can have its own label; unlabeled keys are named Key 1, Key 2, …
• Clicking a card's title, value or empty area opens the Key details dialog, where you can:
  • view every key in the entry;
  • copy any key with one click;
  • reveal / hide;
  • click ☆ to change the default key;
  • jump straight to editing.

Categories, search and sorting

• Create, rename and delete categories in the left sidebar; drag its right edge to resize the sidebar.
• Settings → Categories: use the ↑ / ↓ buttons on each row to reorder categories; changes apply and save as soon as the dialog closes.
• Search filters by name, category and note.
• Sort by created time (new/old), updated time (new/old), or name A→Z / Z→A.

Copy and reveal

• Every key row has copy / reveal / edit / delete actions.
• “Show all / Hide all” toggles the whole current list at once.
• Clipboard content written by Key Center is cleared on lock or exit when it has not been replaced by something else.

Bilingual UI

• 简体中文 / English interface, covering the main window, unlock/setup screen, Settings, every dialog, prompt, error, empty state and export text;
• Switch in Settings → top-right 中文 / English: a confirmation opens immediately in the target language; confirming safely saves settings and restarts, while cancelling reverts the choice and returns to Settings;
• All text comes from one shared dictionary, so future features can add both languages in one place.

Version and project link

• The current version (for example v1.8.8) and the official GitHub icon appear to the right of the app name;
• Click the version to open the Releases page;
• Click the GitHub icon to open the repository — useful for source, issues and downloads.

Window and dialog polish

• Every dialog uses the shared top title bar; the title appears once and the native duplicate caption is gone;
• Dialogs have four-sided shadow, a close button, dragging, Esc-to-close and basic open/close motion;
• Settings, category dialogs, add/edit Key, Key details, change password, export verification, confirmations and information dialogs share the same visual language.

Plaintext export

• Use the download icon or Ctrl + E to export all keys into a category-grouped .txt file.
• You must re-enter the master password before exporting.
• The export marks each entry's default key, making migration or offline backup straightforward.
• ⚠️ The exported file is plaintext. Do not upload it or share it, and delete it when you are done.

Themes and appearance

• Dark / Light / Follow system themes, switchable live in Settings.
• The sun / moon icon in the header toggles dark and light instantly (Ctrl + T); “Follow system” tracks the Windows app theme.
• On Windows 11, an Acrylic backdrop and rounded window corners complement the glass-style cards, panels and thin scrollbars.
• Full high-DPI / multi-monitor support: move the window between displays with different scaling and the UI re-layouts for the current DPI.

Window memory and auto-lock

• Remembers the main window size and position, sidebar width, sort order and theme preference.
• Configurable auto-lock after 0 / 1 / 5 / 15 / 30 minutes of inactivity.
• Settings → Appearance → Restore default window size resets the window to 1000×700 and centers it on the primary display.
• Only one instance can open the same data file at a time.

Screenshots

Light theme	Dark theme

Settings (with language switch)	Search

Add Key	English UI

Quick start

Requirements

• Windows 10 / Windows 11 (64-bit)
• The built-in .NET Framework 4.x (included with Windows 10 / 11; nothing to install)

Download and run

1. Download KeyCenter.exe (or the portable archive) from Releases.
2. Put KeyCenter.exe in any folder and double-click it.
3. On first launch, set a master password (at least 6 characters).
4. Enter that password on subsequent launches to see all your keys.
5. The first launch uses Chinese by default; switch to English in the top-right of Settings, confirm in the target language and restart.

No installation, no registry writes. To uninstall, simply delete the executable and its data files.

Keyboard shortcuts

Shortcut	Action
Ctrl + N	Add a key
Ctrl + F	Focus search
Ctrl + L	Lock
Ctrl + T	Toggle dark / light
Ctrl + E	Export all keys (master password required)
Ctrl + S	Retry a failed save
Enter	Submit the password on the login / setup screen

Data & security

• Encryption: AES-256-CBC + PBKDF2-HMAC-SHA256 (210,000 iterations) + HMAC-SHA256 integrity check.
• The master password is never stored; it is used only to derive the key. If you forget it, it cannot be recovered.
• Fully offline: the app itself makes no network requests — no uploads, no telemetry, no update checks; GitHub links are handed to the system browser.
• Safe writes: data is written to a temporary file, flushed, then committed; the previous version is kept as an encrypted .bak backup.
• Auto-lock: after the configured idle time the vault locks; locking or exiting clears the session key and clipboard content written by Key Center.
• Single-instance protection: only one instance can open the same data file, preventing concurrent writes.

Key Center is not a replacement for a full password manager. Keep your master password safe and back up the encrypted data file regularly.

For security reports, see SECURITY.md.

Portable layout

KeyCenter.exe        Main application (single portable file)
keycenter.dat        Encrypted local data file (created after setting a password)
keycenter.dat.bak    Encrypted backup of the last successful save
keycenter.cfg        UI preferences (theme, language, window position, sidebar width, sort order); plain text, no secrets

• To move to another PC or folder, copy KeyCenter.exe and keycenter.dat together; keycenter.cfg is optional.
• Deleting keycenter.dat erases all data — use with care.
• All UI preferences live next to the executable; nothing is written to the registry or user-profile directories.

Build from source

You only need the .NET Framework 4.x compiler that ships with Windows 10 / 11 — no Visual Studio or .NET SDK required.

powershell -ExecutionPolicy Bypass -File .\build.ps1

The build produces KeyCenter.exe and keycenter.ico in the project root.

Stack

• Pure C# WinForms with hand-written layout and custom-drawn controls
• Compatible with C# 5 / .NET Framework 4.x
• No NuGet, no third-party runtime dependencies
• Single-file output, no installer

Self-test

.\KeyCenter.exe --selftest selftest.log

SELFTEST OK means the encryption, serialization and file I/O self-test passed.

Regression gate

Automated checks for encryption, save, lock, export, theme, DPI and bilingual coverage:

powershell -ExecutionPolicy Bypass -File .\tests\regression.ps1

A passing run prints SELFTEST OK, LOCALIZATION/METADATA AUDIT OK and REGRESSION PASSED. See REGRESSION.md for the manual UI checklist. UI/dialog automation uses the checked-in helper in tests/ui/README.md; test processes are force-closed in finally.

FAQ

I forgot my master password. Can it be recovered?
No. Delete keycenter.dat and start over.

Does it upload anything?
No. The app itself makes no network requests; all data stays encrypted on your machine. GitHub links open in your system browser.

How do I move to a new PC?
Copy KeyCenter.exe and keycenter.dat together. Include keycenter.cfg if you also want to keep window, theme and language preferences.

Can I run it from a USB drive?
Yes. It is fully portable; the data file lives next to the executable.

Why does antivirus occasionally flag it?
This is common for unsigned single-file executables. The source is fully public, and you can rebuild it yourself with build.ps1.

License

MIT License © 2026 verneuil

---

_{Built with plain C# and WinForms. No accounts, no cloud, no tracking.}