TokenLens — AI API Cost Monitor

I got a £340 Anthropic bill last month and had no idea it was coming. The usage dashboard is fine but you only check it after the damage is done.

So I built TokenLens. It shows the cost of every API call in your VS Code status bar as it happens.

How it works

TokenLens runs a local proxy on your machine. Point your SDK at it with one env var and every API call shows its cost in real time. No code changes needed.

OPENAI_BASE_URL=http://localhost:4247/openai
ANTHROPIC_BASE_URL=http://localhost:4247/anthropic

Every call passes through the proxy. TokenLens reads the token counts, calculates the cost, and updates your status bar instantly — including streamed responses.

Your API keys and request data never leave your machine.

Setup

Install the extension
Cmd+Shift+P → TokenLens: Setup API Tracking
Select your providers — env vars are added to your .env automatically
Restart your dev server and start coding

Features

Live status bar — see today's spend at a glance: ⚡ $0.23
Full dashboard — cost by model, by provider, per call
Budget alerts — notified when you hit 75% or 90% of your monthly limit
All major providers — OpenAI, Anthropic, Google Gemini, Mistral
Streaming support — works with streamed responses
Zero code changes — one env var, that's it

Supported models

Provider	Models
OpenAI	GPT-4o, GPT-4o mini, o1, o3-mini
Anthropic	Claude Opus, Claude Sonnet, Claude Haiku
Google	Gemini 2.5 Pro, Gemini 1.5 Flash
Mistral	Mistral Large

Commands

Command	Description
`TokenLens: Setup API Tracking`	Add proxy env vars to your project
`TokenLens: Open Cost Dashboard`	View full cost breakdown
`TokenLens: Set Monthly Budget Alert`	Set a spending limit
`TokenLens: Reset Usage Data`	Clear all recorded data

Free vs Pro

	Free	Pro
Real-time cost tracking	✅	✅
Status bar display	✅	✅
History	7 days	Unlimited
All providers	✅	✅
CSV export	—	✅
Cloud backup	—	✅
Price	Free	£19/mo

Upgrade to Pro

Privacy

All data stays on your machine. The proxy runs on 127.0.0.1 and is never accessible outside your computer. Nothing is sent to any server on the free plan.