The cheapest model that passes. Every week.

Drop in the usage export from OpenAI, Anthropic or OpenRouter. In two minutes you'll see where your AI bill goes and what you pay for nothing. Before you switch to anything cheaper, we test it on your real requests.

Free. Your file is read in your browser and never reaches us.

On your phone? Email yourself the link for your laptop.

Where the bill leaksSAMPLE · A MONTH
Missed caching$96–240
Reasoning on easy requests$42–84
No batch discount$15–62
Repeats and failures$19–28
Sample bill X-ray5 models
$175–415
ESTIMATED SAVING A MONTH · ON A $1,089 BILL
4 leaks found · 1 model swap worth testing
Cheaper model testEXAMPLE · GPT-6-LUNA
147/150requests as good as today's model
req_0412 refund replyPass
req_0977 invoice JSONPass
req_1310 long threadWorse

Where AI bills leak

Gosset measures each of these in your own traffic and puts a monthly dollar figure on it.

Missed caching

Your system prompt goes out with every request, and you may be paying full price for it every single time.

Retries and duplicate calls

A timeout fires, your code retries, and you pay for both calls.

Reasoning you don't need

Reasoning models think before they answer, and every hidden token is billed, even when the answer is a single word.

Work that could wait

Nightly reports and background jobs that don't need an instant answer, billed at the instant price.

Models being retired

When a model your app calls is retired, its replacement can cost more or answer differently. We test the replacement on your requests first.

A bigger model than the job needs

The model you picked at launch is rarely the cheapest one that still works today. We find the one that is, and show you which answers would change.

Bill X-ray

This page reads your file inside your browser, so it never reaches us. If you want to check, turn off your wifi after the page loads. It still works.

Where to find the file

  1. OpenAIPlatform dashboard, Usage page, Export. The file is named completions_usage_…csv.
  2. AnthropicClaude Console, Usage page, Export. The file is named claude_api_tokens_…csv.
  3. OpenRouterActivity page, Export, CSV. Use the per-request export: it has a generation_id column.
Usage exports hold token counts, model names and dates. They do not contain your prompts, your users' messages or your API keys.

How it works

You see your numbers before we ask for anything.

1Takes 2 minutes

X-ray your bill

Spend by model, the share of your input served from cache, retries you paid for, and any model with a shutdown date.

Free, try it now →
Sample bill$1,089 a month
  • claude-sonnet-5-5$329
  • gpt-5.4-mini$271
  • gpt-4o shuts 14 Jan$246

95% of input paid at full price

2Under an hour

Break-test the switch

Paste one line into Claude Code or Cursor. Your agent sends us a sample of real requests with personal details masked. We test the replacement and cheaper models and show you every answer that got worse.

$149 one time, per app
Example break testgpt-4o-mini → gpt-6-luna
147 of 150 requests as good as today's model
req_1310 · long support threadWorse

Today's model quoted the 14-day refund window from message 3. The cheaper model missed it.

3Every week

Stay on the cheapest model that passes

We test each week's new models on your saved requests. You only hear from us when a switch would save money or a shutdown is close.

From $29 a month
Example weekly noteMonday
$90 a month to save on short replies
Sonnet 5.5 → Haiku 5.5passes 150 of 150

The change is ready to paste into your coding agent. Nothing else needs your attention this week.

FAQ

Anything else: contact us.

How much will I save?

On the sample bill, $175 to $415 a month on a $1,089 bill. Yours depends on your caching, retries, batch use and models, so we don't quote a percentage. The free X-ray shows your own numbers in two minutes: what you spend on each model, how much input you pay full price for, and what is going to models that are shutting down. The break test then measures what a cheaper model would save on your real requests, and what it would break.

Is my usage file uploaded anywhere?

No. The X-ray is plain JavaScript running in your browser. The file is read on your device and never sent to us or anyone else. The page loads no analytics or outside scripts.

How accurate are the dollar amounts?

OpenAI and Anthropic exports contain token counts but no prices, so we multiply your tokens by each model's published list price, including cached and batch rates. If you have negotiated prices or credits, your real bill will be lower. OpenRouter exports include the actual cost of each request, which we use as is.

Where do the shutdown dates come from?

From OpenAI's and Anthropic's published deprecation pages. We check them every week and show the date we last checked under your results.

What happens to my requests in the break test?

Your coding agent masks emails, phone numbers, card numbers, addresses and names before anything leaves your machine. We use the masked requests only to run your test, and delete them after 14 days unless you join a weekly plan, which keeps them as your test set until you cancel.

Will a cheaper model be just as good?

Sometimes, not always. Even when a new model scores better on average, studies of real migrations find that 4% to 15% of individual requests get worse. That is why we test on your own requests and list each answer that changes, instead of quoting a benchmark.

Why is it called Gosset?

William Sealy Gosset was a Guinness brewer who invented a statistical test for telling whether a cheaper batch is as good as the original, from only a few samples. That is what we do with AI models. Read the story.