Using Codex and Playwright When There Is No API

Everybody likes an API. It is the clean version of an integration: documented endpoints, structured responses, credentials meant for software, and hopefully somebody else’s problem when the implementation changes.

But plenty of useful systems do not have one. Or they have an API that covers part of the product but not the screen a team actually needs. The data is there, behind a normal login, and somebody is opening a browser and copying it into a spreadsheet.

That is a good place for browser automation.

We have been looking at a practical combination of Playwright and Codex for this kind of work. Playwright drives a real Chrome browser. Codex can work with a browser exposed over the Chrome DevTools Protocol (CDP), which makes it useful for exploring an application and helping build the automation. The important piece is that the login stays human: someone who is authorized to use the site signs in and completes MFA themselves. The automated job uses the resulting browser session; it does not try to get around the login.

A concrete example is recording live odds from sportsbooks such as FanDuel or BetMGM. If an organization is allowed to collect and use the data, that is a much better job for a computer than for someone watching pages and updating a sheet all day.

The browser is sometimes the integration

This is not an argument to scrape everything. If there is an official API that does the job, use it. It is almost always less fragile and easier to support.

But sometimes the browser is the only interface available to the user. A person can log in, look at a live market, and see the numbers, but there is no supported endpoint for getting the same information into an internal system. In that situation, the browser can be the boundary between the site and your workflow.

There are obvious limits. The account needs to be authorized, and the intended use needs to comply with the site’s terms, contracts, and applicable law. That matters especially for sportsbooks, where access and permitted use can vary by operator and jurisdiction. This is not a way to bypass MFA, CAPTCHAs, rate limits, or other controls.

Getting a logged-in browser session

Playwright is a browser automation framework. It can launch Chromium or Chrome, navigate pages, click buttons, fill forms, and read what the page renders.

The feature that makes authenticated automation workable is a persistent browser profile. Instead of starting fresh every time, Playwright launches Chrome with the same profile directory. That lets it retain browser state such as cookies and sessions when the site permits it.

The first run is simple: launch a visible browser, log in normally, handle the two-factor prompt, and make sure the page you need is available. After that, the job can reopen that same profile. It can run visibly while somebody is building or debugging it, then run headlessly when it is ready to collect data on a schedule.

import { chromium } from "playwright";

const userDataDir = "/secure/path/to/browser-profile";
const context = await chromium.launchPersistentContext(userDataDir, {
  channel: "chrome",
  headless: false, // first run: let the account owner log in
});

const page = await context.newPage();
await page.goto("https://example.com/login");

// The authorized user completes sign-in and MFA in this browser window.

That profile directory is sensitive. It may contain an active session, so treat it like a credential: keep it in approved storage, restrict who can access it, and do not put it in source control or logs. Also plan for it to expire. The site decides how long a session lasts. If the job finds a login page again, it should stop and let a person reauthenticate.

Asking Codex to do the tedious part

The page is usually the part that makes these projects annoying. Modern web applications load data after the page appears, change the DOM as markets update, and use selectors that are not obvious until you can inspect the live application.

This is where Codex helps. With the authenticated browser connected over CDP, you can ask it to inspect the page, find the market and selection elements, and build the Playwright script around what is actually there. It is much faster than guessing at selectors from a screenshot or trying to reverse engineer an undocumented backend.

A reasonable first prompt is something like:

Set up Playwright with a persistent Chrome profile and launch it visibly so I can log in. Once I have an authenticated session, use that session to inspect the live odds page and build a script that records the event, market, selection, displayed odds, and collection time.

Codex is helping with the implementation; it is not replacing the account holder. Keep that line clear. It should not be asked to find credentials, solve MFA, or work around controls the site has put in place.

A live-odds collector

Say the job is to keep an internal, timestamped record of odds for a set of games and markets.

First decide what an observation is. At a minimum, it will probably include the sportsbook, event, market, selection, displayed odds, the source page, and the time the value was seen. That last field matters: a number collected at 2:00 PM is not the same thing as a number collected five minutes later.

Next, use the visible browser session to get to the right market and let Codex inspect the rendered page. The job needs to know when the market is actually loaded, how a suspended or unavailable price is represented, and which labels or attributes are stable enough to use as selectors. Prefer user-facing labels where possible over a long chain of generated CSS classes that will disappear in the next redesign.

Once that is understood, the collector can launch the same persistent profile in headless mode, visit only the pages it needs, validate what it finds, and write normalized records to a database or queue.

const context = await chromium.launchPersistentContext(userDataDir, {
  channel: "chrome",
  headless: true,
});
const page = await context.newPage();

await page.goto(targetMarketUrl, { waitUntil: "domcontentloaded" });
await page.getByRole("heading", { name: /live odds/i }).waitFor();

const collectedAt = new Date().toISOString();
const observations = await page.locator("[data-market]").evaluateAll((markets) =>
  markets.map((market) => ({
    market: market.getAttribute("data-market"),
    text: market.textContent?.trim(),
    collectedAt,
  }))
);

The code above is deliberately generic. The real selectors should come from the target site and should be tested against its actual states. The useful outcome is not just a script that reads a page once. It is a small internal data source that dashboards, reports, or models can rely on without each one having to understand the sportsbook’s UI.

The unglamorous stuff is what makes it work

A browser job will change when the website changes. That is normal. The difference between a useful integration and a fragile script is how it behaves on a bad day.

Keep the browser profile locked down. Save where each observation came from and when it was collected. Alert when the job suddenly gets no results, sees a login screen, or returns far fewer records than normal. And give somebody a straightforward way to rerun the visible browser and refresh the session.

That is enough to turn a manual task into something dependable without pretending the website is an API.

For companies sitting on useful data behind logins, this is a practical option: a person handles the authorization once, Playwright keeps the browser state, and Codex speeds up the work of turning what is on the screen into structured data.