Privacy guide
How websites link accounts, and which signals a browser profile can separate
Websites rarely link two accounts on one clue. They match several signals, some from your browser and some from you. This guide lists them and says plainly which ones a separate browser profile can keep apart.
Direct answer
Websites link accounts by matching signals the accounts share. Some come from the browser: cookies, site storage, the fingerprint and the IP address. Others come from you: your email address, phone number, payment card, contacts, writing style and active hours. A separate browser profile can split the browser signals, and a proxy per profile can split the IP address. No browser can split the personal signals. Those need separate details and separate habits.
The linking signals at a glance
Weak signals narrow the field. A shared IP address can be a household or a VPN server. Strong signals confirm a match: a shared email address or card is close to proof.
| Signal | How it links you | Can a separate browser profile separate it? |
|---|---|---|
| Cookies and storage | A stored ID shows up in both accounts’ sessions. | Yes. Each profile has its own cookies and site storage. |
| Browser fingerprint | Both accounts show the same device and browser traits. | Partly. Profiles in one normal browser look almost the same. Profiles with their own fingerprint values report different traits. |
| IP address | Both accounts connect from the same address, often at the same times. | Partly. Only if each profile has its own proxy or VPN route. |
| Timezone and language | A rare mix narrows the field. A clock that does not match the IP location stands out. | Partly. A profile can set both, but they should match its IP address. |
| Email address | The same sign-up or recovery address. Ad platforms also match email lists that businesses upload. | No. Use a different address or an email mask. |
| Phone number | The same number for sign-up, codes or recovery. Other people’s uploaded contacts can match it too. | No. |
| Payment details | The same card, billing name or billing address. | No. |
| Contacts and social graph | Both accounts follow, message or store the same people. Uploaded address books feed friend suggestions. | No. |
| Behavior and writing style | The same active hours, topics, phrases and spelling habits. | No. |
| Login from the same device | Both accounts sign in from one browser profile, one app or one account switcher. | Partly. Profiles keep sessions apart if each account only ever signs in from its own profile. Apps on one phone share that phone. |
Signals no browser can fix
Half of the table is about you, not your browser. No profile, proxy or fingerprint setting touches these signals.
- Email and phone. Sites see them at sign-up and recovery. Facebook’s help center says your profile can be suggested to people who uploaded your phone number or email address. An email mask, such as Firefox Relay or Apple’s Hide My Email, gives each site a different address. The mask service still knows that all of them are yours.
- Payment. A card ties purchases to one legal name. A payment processor can see the same card across many shops.
- Social graph. If both identities follow the same small circle of people, the overlap itself links them.
- Behavior and writing style. Active hours, favorite phrases and spelling habits follow you. Researchers call writing-style matching stylometry.
- Mobile apps. An app on your phone can read device details that a desktop browser profile never changes.
- Mistakes. One sign-in to the wrong account in the wrong profile can link both identities. Once a site has stored that link, a new setup does not remove it.
Checklist for keeping two identities apart
Use this list when you keep two identities for privacy, such as a work persona and a private one, or a pen name.
- Give each identity its own email address. Do not use one as the recovery address of the other.
- Do not share a phone number. Leave optional phone fields empty.
- Keep payment details apart, or do not pay from one of the identities at all.
- Use one browser profile per identity. Never sign in to the other identity there, not even once.
- Do not sign both profiles in to one browser sync account or one extension account. That account joins them.
- If the sites compare IP addresses, give each profile its own proxy or VPN route. Keep the timezone and language in line with that IP address.
- Keep the social graphs apart. Do not follow the same small circle from both, and do not upload your address book.
- Keep personal details apart: names, photos, home town and employer.
- Keep apps for each identity on a separate device or a separate user account on the phone.
- Test both profiles. Open a public checker, such as the EFF’s Cover Your Tracks, in each one and compare the results.
Where AliasMode fits
AliasMode is a free, open-source desktop app for Windows, Mac and Linux. It covers the rows marked yes and partly. Each profile has its own data folder, its own proxy and its own fingerprint values from a stable seed. The timezone and language follow the exit location of the proxy.
Frequently asked questions
Can websites tell if two accounts use the same computer?
Often, yes. Two accounts in one normal browser share cookies, the IP address and almost the whole fingerprint. Separate profiles split the cookies. Traits such as the real graphics card can still match.
Does a VPN stop websites from linking my accounts?
It changes only the IP signal. If both accounts use the same VPN server, they share that IP address too. Cookies, the fingerprint, your email address and your behavior can still link them.
Can Chrome profiles keep two accounts apart?
They keep cookies and site storage apart. They share the same browser, hardware and network, so the fingerprint and IP address are nearly the same.
Do email aliases stop account linking?
They stop a site from matching your real address. The alias service still knows every alias it forwards to you. A shared phone number, card or set of contacts can still link the accounts.
Can I unlink accounts after a site has linked them?
Usually not. Once a site has stored a link, changing your setup does not remove it. Plan the separation before you use the second identity for the first time.