How do you manage cookies in Selenium?

Cookies are useful for setting up authentication or feature flags without repeating the login UI. They are also a source of test leakage when a shared browser keeps a session between tests. Per-test driver isolation solves the leakage; cookie APIs handle deliberate setup.

driver.get("https://example.com");

Cookie session = new Cookie.Builder("session_id", token)
    .domain("example.com")
    .path("/")
    .isHttpOnly(true)
    .isSecure(true)
    .build();

driver.manage().addCookie(session);

Cookie current = driver.manage().getCookieNamed("session_id");
Assert.assertEquals(current.getValue(), token);

driver.manage().deleteCookieNamed("session_id");
driver.manage().deleteAllCookies();

• getCookies returns all cookies visible to the current page
• addCookie requires a matching domain and path, or the browser may reject it
• deleteCookieNamed removes one cookie; deleteAllCookies clears the current session
• HttpOnly cookies cannot be read by page JavaScript but are still visible to WebDriver
• SameSite and Secure restrictions can prevent a cookie from being sent in some contexts
• Injecting a session cookie is faster than UI login but can mask login regressions

Use cookie injection for tests that are not about authentication, and keep a small number of real login tests that exercise the UI or API. If the token is short-lived, generate it per run rather than committing a static value. Never commit production cookies or secrets.