Getting Started with Mercury

Mercury is a native API client that actually feels native. Instant startup. 60fps scrolling. Zero input lag. No subscriptions.

What is Mercury?

Mercury is a native desktop API client built with Rust and GPU-accelerated rendering. Unlike Electron-based tools that feel like slow websites, Mercury responds the instant you click.

Key philosophy:

• Files, not databases — Your requests are plain .json files you can version control
• No accounts required — Your data stays on your machine
• Keyboard-first — Send requests with ⌘+Enter (Mac) or Ctrl+Enter (Windows/Linux)
• Live sync — Edit in VS Code, see changes instantly in Mercury

Why Mercury over Postman/Insomnia?

Feature	Postman	Insomnia	Mercury
Startup Time	3-5 sec	2-4 sec	<300ms
UI Frame Rate	Sluggish	Variable	60fps native
Input Latency	50-100ms	30-50ms	<16ms
Scrolling	Janky	Okay	Buttery smooth
Binary Size	~500MB	~400MB	6MB
Account Required	Yes	Yes	No
Price	$14-25/mo	$5-18/mo	Free forever
Open Source	No	Partially	100%

Installation

🍺 macOS (Homebrew) - Recommended

brew install --cask harry-kp/tap/mercury

Then launch from Applications or run mercury in terminal.

First time using Mercury?

After installation, search "Mercury" in Spotlight (⌘ Space) to launch the app.

---

⚡ Alternative: Shell Installer

macOS / Linux:

curl --proto '=https' --tlsv1.2 -LsSf https://github.com/Harry-kp/mercury/releases/latest/download/mercury-installer.sh | sh

Windows (PowerShell):

irm https://github.com/Harry-kp/mercury/releases/latest/download/mercury-installer.ps1 | iex

Then launch:

mercury

Getting "command not found"?

Restart your terminal or run source ~/.zshrc (or ~/.bashrc) to reload your PATH.

Want it in your Applications folder?

The installer puts mercury in ~/.cargo/bin. Here's how to set it up like a traditional app:

macOS: Add to Applications + Dock

mkdir -p /Applications/Mercury.app/Contents/MacOS && \
cp ~/.cargo/bin/mercury /Applications/Mercury.app/Contents/MacOS/ && \
cat > /Applications/Mercury.app/Contents/Info.plist << 'EOF'
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>CFBundleExecutable</key>
    <string>mercury</string>
    <key>CFBundleName</key>
    <string>Mercury</string>
    <key>CFBundleIdentifier</key>
    <string>com.mercury.app</string>
</dict>
</plist>
EOF

Now search "Mercury" in Spotlight (⌘ Space) and drag to Dock!

Windows: Pin to Start Menu

1. Open File Explorer → %USERPROFILE%\.cargo\bin\
2. Right-click mercury.exe → Create shortcut
3. Right-click the shortcut → Pin to Start

Linux: Add to app launcher

cat > ~/.local/share/applications/mercury.desktop << 'EOF'
[Desktop Entry]
Name=Mercury
Exec=$HOME/.cargo/bin/mercury
Type=Application
Categories=Development;
EOF

Troubleshooting

macOS Gatekeeper error ("developer cannot be verified"):

1. Run mercury (it will fail)
2. Go to System Settings → Privacy & Security → Click "Allow Anyway"
3. Run mercury again

Windows SmartScreen: Click "More info" → "Run anyway"

Your First Request in 60 Seconds

1. Launch Mercury — The app opens with a clean workspace

2. Create a request — Click the + button or press ⌘+N

3. Enter the URL — Type https://httpbin.org/get in the URL bar

4. Send it — Press ⌘+Enter (Mac) or Ctrl+Enter (Windows/Linux)

5. View the response — The JSON response appears in the right panel with syntax highlighting

Quick Start

Want a faster walkthrough? Check out the Quick Start guide for a 5-minute tour.

Interface Overview

Mercury uses a 3-column layout:

Panel	Purpose
Sidebar (left)	Browse your collections and folders
Request (center)	Edit URL, headers, body, and auth
Response (right)	View response body, headers, and timing

Next Steps

• Quick Start — 5-minute guided tour
• Working with Requests — Deep dive into the .json format
• Environment Variables — Use {{variables}} in your requests
• Keyboard Shortcuts — Master the keyboard-first workflow