# One proxy per browser profile, and why > One proxy per browser profile means one exit per profile. With a residential seller that means one session id each, or two profiles share an address. Source: https://mosaicbrowser.com/guides/one-proxy-per-browser-profile ## One proxy per browser profile: why the sessions must differ Give each browser profile its own proxy exit, because a profile is meant to look like one separate person and the address is the first thing a site compares. With a residential seller, its own proxy means its own session id: two profiles on one session leave from one address. ![One profile, one proxy session, beside a screenshot: a proxy provider in Mosaic: one gateway line that mints a separate session for every profile](https://mosaicbrowser.com/covers/one-proxy-per-browser-profile.webp) The rule is one proxy per browser profile, and the word that trips people up is "proxy". With a list of static addresses, one line is one exit and the rule is easy to keep. With a residential seller you get one gateway line for the whole account, and what decides the exit is the session id written inside it. Paste the same line into five profiles and they share one address, even though each one "has a proxy". Each platform's own terms decide how many accounts you may run there. Mosaic keeps accounts you are entitled to run apart; it does not change what a platform allows. The [legal side of multiple accounts](https://mosaicbrowser.com/guides/is-it-legal-to-have-multiple-accounts) is a separate question from the proxy. ## Why a profile needs its own exit A profile exists to be one browser that has nothing in common with the others: its own cookies, its own fingerprint, its own history. The exit IP is the part every site sees on the first request, before any script runs, and it is the cheapest thing for a site to compare across accounts. Two profiles that differ in everything except the address still arrive at the same site from one place. On its own, a shared address proves little. Homes and offices put many people behind one IP, as [multiple accounts on the same IP address](https://mosaicbrowser.com/guides/multiple-accounts-on-the-same-ip-address) explains. It becomes evidence when it sits next to other shared signals, and when the accounts are supposed to belong to different people or different clients. Mosaic is a desktop app Email yourself the link and open it on your computer. [How it works: Provider minting](https://mosaicbrowser.com/features/proxy-providers) ## One proxy per browser profile means one session per profile Residential sellers name a session in the username. Oxylabs' example is `customer-USERNAME-cc-DE-sessid-abcd1234`, and its documentation says requests with that `sessid` go through the same IP while it stays online ([Oxylabs session control](https://developers.oxylabs.io/products/proxies/residential-proxies/session-control), read 2 November 2026). Bright Data says the same from the other side: requests with the same session string use the same peer, and different strings get different peers ([Bright Data residential FAQ](https://docs.brightdata.com/products/residential/faqs)). We checked this against a live Cat Proxies account rather than trusting the dashboard. On its sticky port, `-session-ab12cd34` came back from 97.238.70.34 twice in a row, and `-session-zz99yy11` came back from 152.13.118.218. Same id, same exit; new id, new exit. So the session id is the address, and copying it is copying the address. Three ways people end up sharing one by accident: 1. They paste one gateway line, with its session id, into every profile. 2. They edit session ids by hand across many profiles and miss one, so two profiles keep the same id. 3. They put a fixed line into a template that makes forty profiles, so the whole batch starts on one exit. ## The opposite mistake: no session at all Leave the session out and many gateways rotate, so a single profile appears from a new home on every connection. When we read a rotating endpoint three times in a row it answered Peru, Brazil and Bahrain. One profile, three countries, with one timezone claimed throughout. A logged-in profile needs a sticky session, and its own; [rotating vs sticky proxies](https://mosaicbrowser.com/guides/rotating-vs-sticky-proxies) covers how sellers spell each mode and how long a session lasts. ## What has to agree with the exit Giving a profile its own exit is half the work. The other half is that the profile then has to look like it lives there. A Berlin exit with a browser on Pacific time and an English-only language list is a contradiction a scanner reads in one line, and the fix is in [browser timezone does not match IP](https://mosaicbrowser.com/guides/browser-timezone-does-not-match-ip). WebRTC has to stop sending traffic around the proxy, or the real address shows up anyway. ## How Mosaic gives each profile its own session 1. Save your seller once under Proxies › **Add provider** by pasting one gateway line. Mosaic keeps it as a template. 2. In a profile, under **Connection › Source**, pick that provider and a place if you want one. The field **What this profile will use** shows the minted credential, with the hint "Minted for this profile alone, with a session id nothing else holds." 3. Make profiles in bulk the same way, or from a preset. A preset stores the provider and the pick, never an address, so every profile it makes mints its own session. A preset holding a fixed address is refused, because it would put the whole batch on one IP. 4. Start the profile. Mosaic checks the proxy first and sets the timezone, language and location from the exit it measured. ![A proxy provider in Mosaic: one gateway line that mints a separate session for every profile](https://mosaicbrowser.com/shots/provider-mint.png) *Minted from one line, one session each* If a minted session reaches nothing, Mosaic mints a different one instead of retrying the dead one, and writes it back to the profile. A session you set by hand is never moved. The seller-by-seller details are on [the proxy providers page](https://mosaicbrowser.com/features/proxy-providers). ## Sources 1. [Oxylabs Developers: Residential proxies session control](https://developers.oxylabs.io/products/proxies/residential-proxies/session-control), read November 2, 2026 2. [Bright Data Docs: Residential products FAQ](https://docs.brightdata.com/products/residential/faqs), read November 2, 2026 ## Questions ### Can two profiles use the same proxy if they log in to different sites? Yes, if nothing needs the two kept apart. A shared exit only links profiles on a site where both are present, so a work profile on one site and a research profile on another can share one without either site seeing both. ### Is a different port on the same gateway a different proxy? Sometimes. Some sellers map each port to its own sticky exit, others use ports to choose between rotating and sticky modes. Check the exit through each one before assuming two ports mean two addresses. ### Does one proxy per profile stop sites linking my accounts? It removes one shared signal, the address. Cookies, the browser fingerprint and things like payment details can still connect profiles, which is why the proxy is only one part of keeping them apart. ### What if my proxy is rotating? Then the problem runs the other way: one profile shows up from many places. A logged-in profile needs a sticky session, held for as long as the seller allows, and its own. ## Related [Rotating vs sticky proxies: which one an account needs](https://mosaicbrowser.com/guides/rotating-vs-sticky-proxies): Rotating vs sticky proxies: rotating changes the exit IP per connection, sticky keeps one for a session you name. Logged-in accounts need sticky. [How many accounts per proxy is safe?](https://mosaicbrowser.com/guides/how-many-accounts-per-proxy): How many accounts per proxy? No platform publishes a number. For accounts that must stay apart the answer is one per exit; a shared home IP is different. [How to use a different proxy for each Chrome profile](https://mosaicbrowser.com/guides/use-a-different-proxy-for-each-chrome-profile): Chrome has no proxy setting per profile. Use a proxy extension in each profile, or launch Chrome with its own data folder and --proxy-server. [Browser timezone does not match IP: what it means and the fix](https://mosaicbrowser.com/guides/browser-timezone-does-not-match-ip): Browser timezone does not match IP? Your browser reads the computer's clock, and a proxy or VPN moves only the address. Match the zone to the exit. [Provider accounts: one gateway line, one exit per profile](https://mosaicbrowser.com/features/proxy-providers): Paste your proxy seller's gateway line once and Mosaic mints a separate session for every profile, so each one browses from its own exit address. [How do websites detect multiple accounts?](https://mosaicbrowser.com/guides/how-do-websites-detect-multiple-accounts): Websites detect multiple accounts by what two accounts share: cookies, the IP address, the browser fingerprint, payment and phone details, and habits.   ## Run this guide on your own accounts Every Mosaic profile is a fingerprint, a proxy exit and a cookie jar that agree with each other, kept on your computer. Free holds 3 profiles. Pro is $49 a month for any number. Mosaic is a desktop app Email yourself the link and open it on your computer.