Codex Cost Tracker

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Compact WinUI 3 desktop app for Windows that tracks Codex/Codex App costs per chat and shows estimated usage costs in near real time.

What it does

• Monitors ~/.codex/sessions and ~/.codex/archived_sessions
• Pulls pricing data from the official OpenRouter Models API
• Estimates per-conversation and total spend from token usage records
• Refreshes automatically when session files change
• Lets you manually refresh chats and prices from the UI

Requirements

• Windows 10 version 1809 or newer
• .NET 9 SDK for local builds
• Internet access for OpenRouter pricing sync

Quick start

Run the published app:

powershell -ExecutionPolicy Bypass -File .\Start-CodexSpendPopout.ps1

Force a fresh publish before launch:

powershell -ExecutionPolicy Bypass -File .\Start-CodexSpendPopout.ps1 -Build

Build from source

Build the project:

dotnet build .\CodexSpendMonitor\CodexSpendMonitor.csproj

Publish a self-contained executable:

dotnet publish .\CodexSpendMonitor\CodexSpendMonitor.csproj -c Release -o .\dist\CodexSpendMonitor

For a runnable local dist/ folder, prefer the launcher script because it also syncs required WinUI generated resources into the publish output:

powershell -ExecutionPolicy Bypass -File .\Start-CodexSpendPopout.ps1 -Build

Repository layout

• CodexSpendMonitor/ - WinUI 3 application source
• Start-CodexSpendPopout.ps1 - convenience launcher for local publish + run
• dist/ - generated publish output, ignored by Git
• dumps/ and *.log - local diagnostics, ignored by Git

How spend is estimated

The app reads session .jsonl files and combines:

• input_tokens
• cached_input_tokens
• output_tokens
• reasoning_output_tokens

with pricing returned by:

• OpenRouter Models API

If a session model cannot be matched to an OpenRouter price entry, the chat is still shown in the UI but the price is marked as unmatched.

Session folder discovery

By default the app watches:

• ~/.codex/sessions
• ~/.codex/archived_sessions

If Codex stores sessions somewhere else on a specific machine, you can override the discovery path with environment variables:

• CODEX_HOME - treated as the parent folder that contains sessions/ and archived_sessions/
• CODEX_SESSIONS_DIR - explicit path to the live sessions folder
• CODEX_ARCHIVED_SESSIONS_DIR - explicit path to the archived sessions folder