Codex Cost Monitor

Monitor and estimate your Codex API cost directly inside VS Code.

This extension scans local Codex session logs and calculates token usage and estimated cost by model, helping developers track their spending and avoid unexpected API charges.

Features

📊 Daily Cost Dashboard

Displays today's API cost with budget comparison.

Example:

## Today
Day: 2026-03-06
Cost: ¥44 (USD $0.26)
Budget: ¥2000
Usage: 2.1%

The progress bar quickly shows how much of the daily budget has been used.

📈 Cost by Model

Displays cost grouped by model.

## Cost by model
Model              | JPY | USD
-------------------+-----+------
gpt-5.4            | ¥42 | $0.25
gpt-5.1-codex-mini | ¥1  | $0.01

Useful for identifying which models consume the most cost.

📅 Monthly Cost Overview

Tracks monthly API spending.

## This Month
Month: 2026-03
Cost: ¥1280
Budget: ¥60000
Usage: 2.1%

Helps estimate long-term usage and spending trends.

📜 Cost History

The extension automatically stores historical cost data.

Daily History

## Daily History
DATE       | JPY | USD
-----------+-----+------
2026-03-06 | ¥44 | $0.26
2026-03-05 | ¥62 | $0.39
2026-03-04 | ¥33 | $0.20

Monthly History

## Monthly History
MONTH   | JPY | USD
--------+-----+------
2026-03 | ¥1280 | $8.00
2026-02 | ¥5400 | $33.75

History is automatically stored and maintained.

⚠ Spending Forecast Warning

The extension estimates today's final spending speed.

Example warning:

⚠ At this speed you will spend ¥42000 this month

This helps prevent exceeding monthly budgets early.

🔍 Automatic Log Scanning

The extension automatically scans Codex session logs.

Default location:

~/.codex/sessions

Example structure:

~/.codex/sessions
  └── 2026
      └── 03
          └── 06
              ├── session1.jsonl
              └── session2.jsonl

Each .jsonl file contains token usage metadata used to estimate cost.

💾 Automatic History Storage

The extension automatically:

• saves daily cost history
• generates monthly summaries
• keeps up to 365 days of history
• sorts records automatically

No manual setup required.

Example Dashboard

# Codex Cost Monitor

rate 1 USD = 170 JPY

## Today
Day: 2026-03-06
Cost: ¥44 (USD $0.26)
Budget: ¥2000
Usage: 2.1%

## Cost by model
Model              | JPY | USD
-------------------+-----+------
gpt-5.4            | ¥42 | $0.25
gpt-5.1-codex-mini | ¥1  | $0.01

## This Month
Month: 2026-03
Cost: ¥1280
Budget: ¥60000
Usage: 2.1%

## Daily History
DATE       | JPY | USD
-----------+-----+------
2026-03-06 | ¥44 | $0.26
2026-03-05 | ¥62 | $0.39

## Monthly History
MONTH   | JPY | USD
--------+-----+------
2026-03 | ¥1280 | $8.00
2026-02 | ¥5400 | $33.75

Installation

1️⃣ Open VS Code

2️⃣ Go to Extensions

3️⃣ Search:

codex-cost-monitor

4️⃣ Click Install

Usage

After installation:

1. Open Command Palette

Ctrl + Shift + P

2. Run:

Codex Cost Monitor: Show Dashboard

3. The dashboard will display:

• Today's cost
• Budget usage
• Model cost breakdown
• Daily and monthly history

Configuration

Settings can be customized in VS Code:

codexCostMonitor.dailyBudgetJpy
codexCostMonitor.usdToJpy
codexCostMonitor.baseDir

Example configuration:

dailyBudgetJpy = 2000
usdToJpy = 170

Supported Models

Current pricing support includes:

• gpt-5.4
• gpt-5.3-codex
• gpt-5.2-codex
• gpt-5.1-codex-mini

Additional models may be added in future updates.

Requirements

• Codex CLI installed
• Codex sessions saved locally

Default path:

~/.codex/sessions

Known Limitations

• Cost values are estimated
• Pricing may change depending on OpenAI updates
• Only sessions containing token usage metadata are counted

Release Notes

1.0.0

Initial release

Features:

• Daily cost dashboard
• Token usage parsing
• Cost by model
• Budget monitoring
• Historical tracking
• Spending forecast