Does Changing a Proxy IP Reset Your Session?

No. Changing a proxy does not clear cookies, log an account out, or create a fresh browser profile. A website can recognize the same session cookie after the IP changes, and an API can still identify the same key.

In a browser

The profile's stored application state remains in place. A website may keep you logged in or ask for verification after noticing the network change; the application decides which behavior to use.

A separate test profile keeps a free-proxy check apart from existing personal sessions. It does not by itself establish anonymity.

In Python Requests

A Requests Session keeps a cookie jar and connection pools. Both requests below use the same Session, even though they select different proxies. Replace the documentation endpoints before use; the HTTP proxy list can supply candidates for this HTTP-proxy comparison.

import requests

with requests.Session() as session:
    session.trust_env = False
    # The same cookie jar remains available across these requests.
    first = session.get(
        "https://example.com/",
        proxies={"https": "http://203.0.113.10:8080"},
        timeout=(5, 15),
    )
    second = session.get(
        "https://example.com/",
        proxies={"https": "http://203.0.113.20:8080"},
        timeout=(5, 15),
    )

For jobs that require independent application sessions, create a separate Session for each job. Clearing only its cookie jar leaves other state, such as custom headers or credentials stored elsewhere, untouched.

An IP-check response and a login check answer different questions. The first can show a changed exit address; remaining logged in does not contradict that observation. Being logged out is not proof of a changed proxy, either: cookies may simply have expired.