Fastbrowse shops a live store and cites every price

What changed

Fastbrowse is the open-source browser agent behind Nebula's browser work, and you can run it yourself with one command. The video is one real run on a live shop, The Pi Hut, sped up with the waits cut. Fastbrowse recorded it itself with --record. The task was the kind of errand you would hand to someone:

I'm building a weather station. Find a Raspberry Pi Pico 2 W and a BME280 temperature, humidity and pressure sensor breakout that is in stock, and add one of each to the basket. Go to checkout, use the email ada@example.com and deliver to Ada Lovelace, Buckingham Palace, London, SW1A 1AA, United Kingdom. Tell me what each part costs, the delivery cost and the order total. Don't pay.

What it did:

• Searched the shop, opened the Pico 2 W and added it to the basket.
• Opened the first BME280 board it found, saw it was sold out, went back to the search results and picked one that was in stock, then added that.
• Opened the basket, went to the shop's checkout, and filled in the email, name and delivery address.
• Read the shipping options and the order summary, and stopped before payment.
• Answered with each part's price, the delivery cost (£3.80, Royal Mail 1st Class Tracked) and the total (£20.10), each cited to the page it came from.

The run took 37 steps and about four minutes, and cost $0.29 in model calls.

How it works

1. With uv installed, uvx fastbrowse "<task>" --start <url> runs the published package. It uses a Browser Use Cloud browser by default, or your own Chrome with --local. This run used local Chrome.
2. Fastbrowse turns the page into a list of the controls actually on it, and Jev, a small choice model, picks the next one. It cannot click something that isn't on the page. In this run Jev made 88 calls: the median took 0.25 seconds and cost $0.00026, and together they cost $0.04. Larger models are only used to plan, read pages and check the answer.
3. Fastbrowse only goes to sites the task or caller names. Submitting, paying, deleting and sending stop at needs_confirmation unless you pass --authorize. Passwords go in with --secret, typed only on the site they belong to, and the models only ever see the secret's name.
4. Factual claims in a complete answer cite verbatim quotes from the pages fastbrowse read. --json gives every step, the quotes and the cost by component. --record saves a captioned video like this one.

Fastbrowse also runs as a Python library, which can return data checked against your own schema, and as a JavaScript package and an MCP server.

Why it matters

Browser agents are usually slow, expensive, or both, because a large model works out every click. Fastbrowse saves the large models for planning and reading, and lets a small model pick from what is on the page. In our recorded head-to-head on 46 tasks, three repeats each on Browser Use cloud browsers, fastbrowse passed 99.2% of runs against 97.8% for the hosted Browser Use agent. Its median was 16.3 seconds against 16.1, and it cost $0.026 a result against $0.284. That is the same speed for under a tenth of the price, and you can check every figure in the answer.