Compare Prices Across Websites With an AI Agent

Capability: parallel runs + output_schema

Use this to find where something is cheapest. TinyAgent runs one browser per site, all at the same time, and every site returns its price in the same JSON shape — so you can sort the results straight away. It works for listed prices and for quotes you only get after filling in a form.

TinyAgent opens Best Buy’s search results for the Logitech MX Master 3S and returns the lowest-priced listing as JSON.

Steps

Start each run on the site’s search results. Put the search in the URL — e.g. bestbuy.com/site/searchpage.jsp?st=logitech+mx+master+3s — so the agent lands on the listings, not the homepage. Fewer steps means a faster run that’s less likely to time out.
Use one schema for every site. Same field names everywhere, with nullable: true on anything a site might not show.
Run them all at once. One run per site, started together, each with a time limit.
Sort what came back. Skip sites that failed or found nothing, then sort by price.

Python
TypeScript

import asyncio
from tinyfish import AsyncTinyFish, AgentConfig, BrowserProfile, ProxyConfig, ProxyCountryCode

SITES = [
    "https://www.bestbuy.com/site/searchpage.jsp?st=logitech+mx+master+3s",
    "https://www.newegg.com/p/pl?d=logitech+mx+master+3s",
]

GOAL = (
    "Look at the first 5 listings for the Logitech MX Master 3S mouse "
    "(the mouse itself, not accessories, bundles, or refurbished units). "
    "Return the one with the lowest price. Set site to the store's name. "
    "Use null for any field the page doesn't show."
)

SCHEMA = {
    "type": "object",
    "properties": {
        "site": {"type": "string"},
        "product_name": {"type": "string", "nullable": True},
        "price": {"type": "number", "nullable": True},
        "currency": {"type": "string", "nullable": True},
        "in_stock": {"type": "boolean", "nullable": True},
        "product_url": {"type": "string", "nullable": True},
    },
    "required": ["site", "product_name", "price", "currency", "in_stock", "product_url"],
}


async def main():
    client = AsyncTinyFish()

    runs = await asyncio.gather(
        *(
            client.agent.run(
                url=url,
                goal=GOAL,
                output_schema=SCHEMA,
                browser_profile=BrowserProfile.STEALTH,
                proxy_config=ProxyConfig(enabled=True, country_code=ProxyCountryCode.US),
                agent_config=AgentConfig(max_duration_seconds=180),
            )
            for url in SITES
        ),
        return_exceptions=True,
    )

    listings = [
        run.result
        for run in runs
        if not isinstance(run, Exception) and run.result and run.result.get("price") is not None
    ]
    for item in sorted(listings, key=lambda item: item["price"]):
        print(f"{item['site']}: {item['price']} {item['currency']}  {item['product_url']}")


asyncio.run(main())

import { TinyFish } from "@tiny-fish/sdk";

type Listing = {
  site: string;
  product_name: string | null;
  price: number | null;
  currency: string | null;
  in_stock: boolean | null;
  product_url: string | null;
};

const client = new TinyFish();

const SITES = [
  "https://www.bestbuy.com/site/searchpage.jsp?st=logitech+mx+master+3s",
  "https://www.newegg.com/p/pl?d=logitech+mx+master+3s",
];

const GOAL =
  "Look at the first 5 listings for the Logitech MX Master 3S mouse " +
  "(the mouse itself, not accessories, bundles, or refurbished units). " +
  "Return the one with the lowest price. Set site to the store's name. " +
  "Use null for any field the page doesn't show.";

const SCHEMA = {
  type: "object",
  properties: {
    site: { type: "string" },
    product_name: { type: "string", nullable: true },
    price: { type: "number", nullable: true },
    currency: { type: "string", nullable: true },
    in_stock: { type: "boolean", nullable: true },
    product_url: { type: "string", nullable: true },
  },
  required: ["site", "product_name", "price", "currency", "in_stock", "product_url"],
};

const runs = await Promise.allSettled(
  SITES.map((url) =>
    client.agent.run({
      url,
      goal: GOAL,
      output_schema: SCHEMA,
      browser_profile: "stealth",
      proxy_config: { enabled: true, country_code: "US" },
      agent_config: { max_duration_seconds: 180 },
    }),
  ),
);

const listings = runs
  .flatMap((r) => (r.status === "fulfilled" && r.value.result ? [r.value.result as Listing] : []))
  .filter((item): item is Listing & { price: number } => item.price !== null)
  .sort((a, b) => a.price - b.price);

console.table(listings);

Result

[
  { "site": "Best Buy", "product_name": "Logitech - MX Master 3S Bluetooth Edition Performance Wireless Optical Mouse ...", "price": 79.99, "currency": "USD", "in_stock": true, "product_url": "https://www.bestbuy.com/product/..." },
  { "site": "Newegg", "product_name": "Logitech MX Master 3S - Wireless Performance Mouse ... - Pale Grey", "price": 87.5, "currency": "USD", "in_stock": true, "product_url": "https://www.newegg.com/..." }
]

Each run is independent and billed separately — one site failing doesn’t stop the others. To check many products or many sites, see Run TinyAgent Across Multiple URLs.

Get a Quote From a Form

Some prices only appear after you fill in a form — shipping, insurance, a moving quote. Start the run on the quote page, put every input in the goal, and say where to stop:

url:  https://postcalc.usps.com/
goal: Get a shipping quote for one parcel:
        - From ZIP: 94107
        - To ZIP: 10001
        - Weight: 2 lb, size 12 x 8 x 4 inches
      Fill in the quote form and return each service shown with its price and delivery estimate.
      Stop at the quote results. Don't create an account, enter payment details, or buy anything.

The run returns every service on the results page — Priority Mail Express, Priority Mail, Ground Advantage and so on — with price and delivery date. Add an output_schema with a services array if you need the same fields every time.

Tip — from ChatGPT or Claude: name the product and every site in one message, e.g. “Compare the price of the Logitech MX Master 3S on Best Buy and Newegg.” Connect once with Run TinyAgent From ChatGPT or Claude.

Common Mistakes

One run asked to visit every site

A single goal like “check Best Buy, then Newegg, then Amazon” makes one long run that can time out before it finishes. Give each site its own run, as above, and cap each with max_duration_seconds so one slow site can’t hold up the rest.

A marketplace seller's price instead of the store's

“The first listing” is often a sponsored result or a third-party seller with a marked-up price. Ask for the lowest price among the first few listings, and say what doesn’t count — accessories, bundles, refurbished units.

output_schema rejected with "type arrays are not supported"

Writing "type": ["number", "null"] returns 400. Use "type": "number", "nullable": true instead — full rules in the Structured Output Reference.

Prices that aren't really comparable

The same product can show a different price, currency, or tax by country. Pin the location with proxy_config.country_code, keep a currency field in the schema, and say which price you want — e.g. “price before tax and shipping”.

A retailer blocks the run

Large retailers often block standard browsers. Use browser_profile: "stealth" with a proxy, as in the sample — see the Anti-Bot Guide.

Run TinyAgent Across Multiple URLs

Run the same goal on many pages at once

Get a TinyAgent Run as Structured JSON

Pin down an exact result shape

Structured Output Reference

Supported types, nullable, and limits

Anti-Bot Guide

Stealth browser and proxy settings

Start Here

Search API

Monitor

Fetch API

Browser API

Research API

Datasets API

Capabilities

Tools & Integrations

Guides

Use Cases

Reference

Compare Prices Across Websites With an AI Agent

Steps

Get a Quote From a Form

Common Mistakes

Run TinyAgent Across Multiple URLs

Get a TinyAgent Run as Structured JSON

Structured Output Reference

Anti-Bot Guide

​Steps

​Get a Quote From a Form

​Common Mistakes

​Related

Run TinyAgent Across Multiple URLs

Get a TinyAgent Run as Structured JSON

Structured Output Reference

Anti-Bot Guide

Steps

Get a Quote From a Form

Common Mistakes

Related