Fiddler Download Setup

Fiddler Download & Setup

Guide the user through downloading, installing, and launching Fiddler Everywhere.

Operating rules

1. This skill is shell-first. Fiddler is not installed yet, so no MCP tools are available.
2. Resolve the current version from the manifest before constructing any download URL. Never hardcode a version number.
3. On Windows - detect opened terminal. Only if it is not powershell - wrap and run the scripts with: powershell.exe -Command 'script'. Use single quotes to wrap the script!

Phase 1 — Check if Fiddler is already installed

Before downloading, check whether Fiddler Everywhere is already installed. If it is installed, also read the installed version and compare it against the latest available release. Only proceed to Phase 2 if the app is not installed or an update is available and the user wants to upgrade.

macOS — detect and version-check

if [ -d "/Applications/Fiddler Everywhere.app" ]; then
  INSTALLED_VERSION=$(/usr/libexec/PlistBuddy -c "Print CFBundleShortVersionString" \
    "/Applications/Fiddler Everywhere.app/Contents/Info.plist" 2>/dev/null)
  echo "INSTALLED: $INSTALLED_VERSION"
else
  echo "NOT_INSTALLED"
fi

If INSTALLED, fetch the latest version for the detected architecture and compare:

ARCH=$(uname -m)
if [ "$ARCH" = "arm64" ]; then
  MANIFEST_URL="https://downloads.getfiddler.com/mac-arm64/latest-mac.yml"
else
  MANIFEST_URL="https://downloads.getfiddler.com/mac/latest-mac.yml"
fi
LATEST_VERSION=$(curl -s "$MANIFEST_URL" | grep '^version:' | awk '{print $2}')
echo "Installed: $INSTALLED_VERSION  |  Latest: $LATEST_VERSION"
if [ "$INSTALLED_VERSION" = "$LATEST_VERSION" ]; then
  echo "UP_TO_DATE"
else
  echo "UPDATE_AVAILABLE"
fi

Linux — detect and version-check

APPIMAGE=$(ls ~/Downloads/fiddler-everywhere-*.AppImage 2>/dev/null | sort -V | tail -1)
if command -v fiddler-everywhere &>/dev/null || [ -n "$APPIMAGE" ]; then
  # Extract version from AppImage filename as the most reliable source
  INSTALLED_VERSION=$(echo "$APPIMAGE" | grep -oP '[\d]+\.[\d]+\.[\d]+')
  echo "INSTALLED: $INSTALLED_VERSION"
  LATEST_VERSION=$(curl -s "https://downloads.getfiddler.com/linux/latest-linux.yml" \
    | grep '^version:' | awk '{print $2}')
  echo "Installed: $INSTALLED_VERSION  |  Latest: $LATEST_VERSION"
  if [ "$INSTALLED_VERSION" = "$LATEST_VERSION" ]; then
    echo "UP_TO_DATE"
  else
    echo "UPDATE_AVAILABLE"
  fi
else
  echo "NOT_INSTALLED"
fi

Windows (PowerShell) — detect and version-check

$installed = Get-ItemProperty `
  "HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\*",
  "HKCU:\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\*",
  "HKLM:\SOFTWARE\WOW6432Node\Microsoft\Windows\CurrentVersion\Uninstall\*" `
  -ErrorAction SilentlyContinue |
  Where-Object { $_.DisplayName -like "*Fiddler Everywhere*" }

if ($installed) {
  $installedVersion = $installed.DisplayVersion
  Write-Host "INSTALLED: $installedVersion"

  $manifest = Invoke-WebRequest "https://downloads.getfiddler.com/win/latest.yml" -UseBasicParsing
  $text = [System.Text.Encoding]::UTF8.GetString($manifest.RawContentStream.ToArray())
  $latestVersion = ($text | Select-String '(?m)^version:\s*(.+)').Matches.Groups[1].Value.Trim()
  Write-Host "Installed: $installedVersion  |  Latest: $latestVersion"

  if ($installedVersion -eq $latestVersion) { "UP_TO_DATE" } else { "UPDATE_AVAILABLE" }
} else {
  "NOT_INSTALLED"
}

Interpreting the result:

• NOT_INSTALLED — continue to Phase 2 to download and install.
• UP_TO_DATE — inform the user their Fiddler Everywhere is already on the latest version and stop further execution of the skill.
• UPDATE_AVAILABLE — tell the user the installed version and the latest version, then ask whether they want to upgrade. If yes, continue to Phase 2 (the new installer will replace the existing one). If no, stop.

Phase 2 — Detect OS and resolve version

Run both commands together. The manifest probe also confirms network access.

uname -s && uname -m
VERSION=$(curl -s "https://downloads.getfiddler.com/mac-arm64/latest-mac.yml" \
  | grep '^version:' | awk '{print $2}')
echo "Latest Fiddler Everywhere: $VERSION"

On Windows (PowerShell):

$env:PROCESSOR_ARCHITECTURE   # AMD64 or ARM64
$manifest = Invoke-WebRequest "https://downloads.getfiddler.com/win/latest.yml" -UseBasicParsing
$text = [System.Text.Encoding]::UTF8.GetString($manifest.RawContentStream.ToArray())
$VERSION = ($text | Select-String '(?m)^version:\s*(.+)').Matches.Groups[1].Value.Trim()
Write-Host "Latest Fiddler Everywhere: $VERSION"

Phase 3 — Download

Use $VERSION resolved in Phase 2 to construct a direct, versioned URL. The .pkg format is preferred on macOS.

macOS

# Apple Silicon (arm64)
curl -L \
  "https://agent-downloads.getfiddler.com/mac-arm64/Fiddler%20Everywhere%20${VERSION}.pkg" \
  -o ~/Downloads/FiddlerEverywhere.pkg

# Intel (x86_64)
curl -L \
  "https://agent-downloads.getfiddler.com/mac/Fiddler%20Everywhere%20${VERSION}.pkg" \
  -o ~/Downloads/FiddlerEverywhere.pkg

Linux

VERSION=$(curl -s "https://downloads.getfiddler.com/linux/latest-linux.yml" \
  | grep '^version:' | awk '{print $2}')
curl -L \
  "https://agent-downloads.getfiddler.com/linux/fiddler-everywhere-${VERSION}.AppImage" \
  -o ~/Downloads/FiddlerEverywhere.AppImage

Windows (PowerShell)

Invoke-WebRequest `
  "https://agent-downloads.getfiddler.com/win/Fiddler%20Everywhere%20$VERSION.exe" `
  -OutFile "$env:USERPROFILE\Downloads\FiddlerEverywhere.exe"

Phase 4 — Install

macOS — PKG (headless, no wizard)

Do not use sudo installer directly — sudo blocks on a password prompt inside the agent's hidden shell where the user cannot type. Use osascript instead, which raises the native macOS authentication dialog that the user can see on screen.

do shell script with administrator privileges runs as root and cannot access ~/Downloads due to macOS sandbox restrictions. Copy the package to /tmp first (world-readable), then install from there.

Run both commands via bash tool calls:

cp ~/Downloads/FiddlerEverywhere.pkg /tmp/FiddlerEverywhere.pkg

Then announce before the next command:

"A macOS password dialog will appear on your screen. Enter your login password there to authorize the installation, then I'll continue automatically."

osascript -e 'do shell script "installer -pkg /tmp/FiddlerEverywhere.pkg -target /" with administrator privileges'

osascript blocks until the user approves the dialog and the install completes. Once it exits with code 0, clean up.

rm /tmp/FiddlerEverywhere.pkg

macOS — DMG (if user prefers drag-and-drop)

hdiutil attach ~/Downloads/FiddlerEverywhere.dmg -nobrowse
cp -R "/Volumes/Fiddler Everywhere/Fiddler Everywhere.app" /Applications/
hdiutil detach "/Volumes/Fiddler Everywhere"

Linux

chmod +x ~/Downloads/FiddlerEverywhere.AppImage
~/Downloads/FiddlerEverywhere.AppImage &

Windows — silent install

Start-Process "$env:USERPROFILE\Downloads\FiddlerEverywhere.exe" -ArgumentList "/S" -Wait

Launch Fiddler:

macOS:

open -a "Fiddler Everywhere" && sleep 15

Linux:

(nohup fiddler-everywhere &>/dev/null &); sleep 15

Windows: Important On windows if the current terminal used is bash, use the specific GitBash script.

PowerShell

$candidates = @(
  "$env:LOCALAPPDATA\Programs\Fiddler Everywhere\Fiddler Everywhere.exe",
  "C:\Program Files\Fiddler Everywhere\Fiddler Everywhere.exe",
  "C:\Program Files (x86)\Fiddler Everywhere\Fiddler Everywhere.exe"
)
$fiddlerExe = $candidates | Where-Object { Test-Path $_ } | Select-Object -First 1
if ($fiddlerExe) {
  $cmdLine = '"' + $fiddlerExe + '"'
  Invoke-CimMethod -ClassName Win32_Process -MethodName Create -Arguments @{ CommandLine = $cmdLine } | Out-Null
  Start-Sleep 15
}

Git Bash

FIDDLER_EXE=""
for dir in "$LOCALAPPDATA/Programs/Fiddler Everywhere" \
           "/c/Program Files/Fiddler Everywhere" \
           "/c/Program Files (x86)/Fiddler Everywhere"; do
  if [ -f "$dir/Fiddler Everywhere.exe" ]; then
    FIDDLER_EXE="$dir/Fiddler Everywhere.exe"
    break
  fi
done
if [ -n "$FIDDLER_EXE" ]; then
  "$FIDDLER_EXE" &
  sleep 15
fi

Phase 5 — Suggest MCP setup

After Fiddler Everywhere is installed and launched, inform the user that there is an automatic MCP setup skill that can configure the Fiddler MCP server connection.

Present the following message:

Fiddler Everywhere is installed and running.

There is an automatic MCP setup skill that can configure the Fiddler MCP server connection for your AI agent. This will allow agent tools to interact with Fiddler directly — capturing traffic, inspecting sessions, creating rules, and more — all from within your editor.

Would you like me to auto-configure MCP now?

Use the ask-questions tool to let the user choose:

• Yes, auto-configure MCP (recommended)
• No, I'll set it up manually later

If the user accepts

Install the fiddler-mcp-setup skill from its remote location and invoke it:

Remote skill URL: https://github.com/telerik/fiddler-agent-tools/tree/master/skills/fiddler-mcp-setup

Follow the fiddler-mcp-setup skill instructions to complete MCP configuration end-to-end.

If the user declines

Acknowledge and let them know they can download the MCP setup skill later at any time.

Troubleshooting