Anti-detect browser for agencies: a browser per client

An agency with twelve clients does not have twelve accounts. It has twelve Meta portfolios, a few Google Ads accounts, a Shopify admin or two, the client's own email newsletter tool, an analytics login that only has a password, and a two-factor code that lives on somebody's phone. Mosaic sorts that by client: a project per client, a profile per login, and in each profile the client's own cookies, exit and codes.

Agency access comes first

The big platforms have proper ways for an agency to work on a client's account without the client's password, and they are better than any browser. Meta lets a business share its Pages and ad accounts with a partner's business portfolio (Meta Business Help Center, read 2 November 2026). Google Ads manager accounts put many client accounts under one sign-in (Google Ads Help). TikTok's Business Center lets an agency request access to a client's ad account or be added as a partner (TikTok Ads Help). Shopify gives partners collaborator accounts, scoped to the parts of a store the client picks (Shopify Help Center). YouTube's channel permissions give a manager a role on a channel without access to the owner's Google Account (YouTube Help). All read 2 November 2026.

Some platforms allow one account per person. LinkedIn's User Agreement says you will only have one account, in your real name, and forbids using someone else's (LinkedIn, read 2 November 2026), so a client's personal profile is not something an agency logs into. Mosaic keeps the accounts you are entitled to run apart; it does not change what a platform allows.

How it works: Provider minting

Where agencies still need a browser per client

Agency access stops at the big platforms. The rest of a client's stack is a username and a password: the newsletter tool, the booking system, the analytics account the founder set up in 2019, a regional marketplace with no partner programme. Agencies end up signing in to those directly, often several clients' versions of the same tool on the same day.

In one Chrome that goes wrong in plain ways. The newsletter tool remembers the last client you signed in as, so a campaign goes to the wrong list. A client's tool sees your office address on twelve unrelated businesses. Somebody pastes a code from the wrong row of the authenticator app. Separate Chrome profiles fix the cookies but share one fingerprint and one network, which is what how sites link accounts walks through.

How an agency sets up Mosaic

1. A project per client. Each project has its own colour and icon, so the client you are working on is visible in the sidebar, and the profile table shows that client only.
2. A profile per login. "Acme - newsletter" holds that one session and nothing else. Logins and two-factor codes are stored per profile, and the companion inside the browser shows that profile's codes only.
3. An exit where the client is. Paste your proxy seller's gateway line once as a provider. Each profile mints its own session, so no two clients share an address, and the profile's timezone and language follow the measured exit.
4. A preset for each kind of client. A preset makes new profiles with the same start pages, bookmarks, tags and provider pick, so onboarding the next client is a few clicks.
5. Leave when the contract ends. Deleting the project moves every profile in it to the trash and closes any browser still open. Trash keeps them 30 days by default.

What stays on your computer

Client sessions are the most sensitive thing an agency holds. Mosaic has no cloud copy of your profiles: profiles, cookies and proxies stay on your computer, and the store and cookie jars are encrypted on disk. Turn on app lock and nothing decrypts without your password. Each profile's downloads go into its own folder, so one client's reports and invoices never sit next to another's. Local first covers what our server does know, which is your plan, your computers and when a profile opens, by an id.

Where Mosaic is the wrong fit

Mosaic has no seats, no roles and no shared profiles. If five account managers need the same client logins on five laptops, that is the platform's user roles or a team product, not us. It also has no scheduler and no shared inbox. It suits a founder-led agency or a specialist who does the hands-on work from one machine. For the paid-media side, browser profiles for client ad accounts has the specifics.

Free covers 3 profiles; Pro is $49 a month, one plan, with no per-profile pricing and a 14-day free trial. See pricing.