Migrating Browser Profiles, Cookies and Proxies to JustBrowser

Moving a team's profiles from one multi-account browser to another sounds risky. You have logged-in sessions, saved proxies and a clear idea of which client or storefront lives in which profile, and nobody wants to rebuild that from memory. In practice a migration is a set of exports and imports, and it goes smoothly when you do it in a fixed order and write down what you have before you touch anything.

This guide is general. It applies whichever multi-account browser you are leaving. By the end, your profiles will be running in JustBrowser with cookies carried over where possible, proxies rebound and settings checked. It is meant for agencies, storefront operators and QA teams moving accounts that they are entitled to hold.

Prerequisites

• Your old browser installed, with the profiles you want to move.
• JustBrowser installed. It runs on Windows x64 and macOS (Apple Silicon). The 7-day free trial requires a card and you are not charged if you cancel inside the seven days, which is enough time to migrate a first batch and judge the result.
• Proxy details written down for each profile: host, port, username, password and type (HTTP, HTTPS or SOCKS5). Export formats vary between tools, and proxy credentials are the item most often missing.
• An inventory. A simple sheet with one row per profile: name, client or storefront, proxy, timezone, language, and who on the team uses it.
• Time. Allow about half an hour for a handful of profiles, a few hours for a larger batch.

No coding is needed for a first migration. Bulk creation through the local REST API (up to 100 profiles per call from a naming pattern) is useful later, but do the first batch by hand. There is no CSV importer, so plan on the app or the API.

Step 1: Export from your old browser

Most multi-account browsers can export in one or both of these ways:

A profile export. This usually bundles the profile's settings, cookies and local storage into a file. Save each file in an organised folder, with one subfolder per profile or client.

A cookies-only export. If sessions are all you need, export the profile's cookies as JSON. It is lighter, and it means you recreate the settings by hand.

What often does not travel cleanly:

• Proxy credentials. Copy them from each profile's proxy settings into your inventory before you export.
• Extension logins. If a browser extension holds a login, such as a password manager, you will sign in again in the new profile.
• Anything tied to the old app. Saved notes or tags inside the old tool are worth copying into your inventory sheet.

Export and import on the same day. Cookies carry expiry dates, and a session exported weeks ago may already be gone.

Step 2: Create matching profiles in JustBrowser

In JustBrowser each profile is its own browser, with its own cookies, storage, proxy and identity parameters, so a profile maps naturally to a client, storefront or test scenario. Create one new profile for each old one, and match the parts that describe where and how it is used:

• Operating system identity. Choose the same family as before, such as Windows or macOS.
• Screen size. Keep it the same unless you have a reason to change it.
• Timezone. Set it to agree with the proxy's location. A German proxy goes with Europe/Berlin.
• Language. Keep it as it was, unless the proxy location changed too.
• Hardware-related values (canvas, WebGL, audio). Let JustBrowser generate these. They are produced to be consistent with each other and with the rest of the profile.

Why not copy the hardware values across? Because they describe a device, and the new browser has its own engine. What matters is that a profile is coherent within itself: the proxy, timezone, language, screen and hardware values all describing the same setup. Trying to replicate another tool's exact values brings no benefit. For how GPU-based values are read in the first place, see our WebGL fingerprinting deep dive.

The exception is a custom value you set on purpose, such as an unusual screen size. Recreate that one by hand.

JustBrowser is built on a custom Chromium engine with native C++ integration, not an extension, so these settings are applied by the engine itself rather than patched on in the page. It covers 40+ identity parameters, and names differ from tool to tool, so map custom settings manually.

Step 3: Import cookies

If the cookies import correctly, the sessions you are entitled to use carry over and you avoid a round of sign-ins.

1. With the new profile stopped, open its cookie import.
2. Choose the JSON file you exported.
3. Review the list for the domains you care about.
4. Save, then open a site you expect to be signed in to and check.

The import reads JSON and Netscape-format cookie files. If your old tool exports something else, convert it to JSON first, then import.

Some sites tie a session to more than cookies, so you may be asked to sign in or confirm your identity once. That is normal, and it is the site doing its job.

Step 4: Rebind proxies

Open each profile's proxy settings and enter the details from your inventory:

• Type: HTTP, HTTPS or SOCKS5
• Host and port
• Username and password, exactly as your provider shows them

JustBrowser's proxy tester shows the exit IP, the provider name, country, city and timezone, latency, a reputation note and flags for proxy, hosting and mobile. Run it before you save and confirm the result matches what you expected. If you expected a German connection and the test shows another country, the credentials or the proxy product are wrong.

If your provider offers sticky sessions with a session ID in the username, reuse the same session ID so the profile keeps the same exit IP. A different session usually means a different IP and location, which some sites will ask you to confirm.

Proxies aren't included in the subscription: bring your own or buy a proxy plan in the app. See the ISP proxy setup tutorial for a worked example.

Step 5: Check each profile

Before anyone relies on a migrated profile, confirm it is set up the way you meant.

• Open the proxy tester again and check the exit location.
• Visit a page that shows what the browser reports, such as BrowserLeaks, and read the individual values: timezone, language, WebRTC address and screen.
• Confirm the timezone and language agree with the proxy's location.
• Confirm the WebRTC address matches the proxy's IP rather than your office connection.

If something does not match what you configured, change that one setting and look again. The usual causes are a timezone that does not agree with the proxy and a language left at the old value. For background on the network-level side of what a site reads, see how TLS fingerprints work.

Step 6: Try it on a low-stakes account first

Pick one migrated profile and use it for a day or two on an account where nothing is at stake, such as an internal tool or a test login. When it behaves as expected, move the rest in batches. If something is off, fix that profile before moving any client-owned accounts.

Common problems

Cookies imported but the site shows signed out

The cookies were probably expired, or in a format that did not import. Export fresh cookies from the old browser and import them the same day. If the format is the problem, convert it to JSON first.

Proxy authentication fails

Re-check the credentials against your provider's dashboard. If the password contains characters such as @ or #, try URL-encoding it or choose an alphanumeric password.

The checker shows a timezone or language mismatch

Edit the profile. Set the timezone to the proxy's location and the language to match.

A site asks you to verify after the move

That is common after a change of device or app. Complete the site's own verification. If an account is restricted, see our Facebook Business Manager guide for the official route, use that platform's own appeal process, and read its rules about holding multiple accounts first: JustBrowser keeps accounts separate, it does not change what a platform allows.

Share profiles with your team

Once you are across, you can invite teammates. Team seats are free and unlimited, and a seat can run the profiles the owner shares with it, with view-only or launch permission and owner, admin, member and viewer roles. A seat cannot create or cloud-sync its own profiles, use the REST API or invite others. That removes the habit of passing passwords around.

After the move

You also get the local REST API and CDP for Playwright, Puppeteer and Selenium. It is bound to 127.0.0.1, authenticates with a Bearer token from the app's AI page, and is documented at justbrowser.app/docs. Profiles sync to the cloud on a subscription.

JustBrowser is $9.99/month or $99.99/year, one plan with unlimited profiles, unlimited cloud sync and unlimited team seats. If you are comparing it with other multi-account browsers such as Multilogin, GoLogin or AdsPower, see the dated comparisons at justbrowser.app, and our myths post on what these browsers can and can't do. If your team checks ads across countries, the ad verification workflow shows how migrated profiles fit that work. If the accounts you are moving run paid campaigns, ClickzProtect can help with click-quality questions, and JustAnalytics offers privacy-respecting analytics for the sites behind them.

More operational guides on the JustBrowser blog.

Frequently Asked Questions

Will I lose my logged-in sessions when I migrate to JustBrowser?

Not necessarily. If you export cookies from your old browser and import them into the matching JustBrowser profile on the same day, many sessions carry over. Cookies that have expired, or sites that tie a session to something else, may ask you to sign in again, which is normal.

Can I migrate profiles that have proxy settings?

Yes, but plan to add the proxy to each JustBrowser profile yourself. Copy the host, port, username, password and type from your old browser first, then enter them in the new profile's proxy settings and test them before saving.

How long does a migration take?

Plan on roughly 5 to 10 minutes per profile when you work carefully, including a check of the proxy and settings. The export from the old tool is quick; recreating, importing and checking each profile is where the time goes.

Does JustBrowser offer comparable profile settings?

JustBrowser covers 40+ identity parameters including canvas, WebGL, audio, fonts, screen, timezone and navigator values. Names differ between tools, so map custom settings by hand. Let the app generate the hardware-related values rather than copying them.

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A multi-account browser for teams, built on a custom Chromium engine, not an extension. Real C++ engine patches at the canvas / WebGL / audio / font / screen layer, so 40+ identity parameters are genuine, not faked. Local REST API + CDP for Playwright, Puppeteer, Selenium. 7-day free trial, card required — then $9.99/month or $99.99/year, unlimited profiles, free team seats.

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