Multilogin

Posted on Nov 15

The Developer’s Guide to Multi-Session Automation

#webdev #automation #puppeteer #multiplatform

Running a single browser automation session is easy. Running two is straightforward. Running 10, 50, or 100 Playwright/Puppeteer sessions in parallel without leaks, mismatched fingerprints, bot detections, proxy errors, or CPU failures is where most setups break.
In this post we’ll go over how developers can safely scale multi-session automation, bypass anti-bot checks, and ensure reliable identity isolation at scale.
Where applicable we’ll also see how developers use Playwright/Puppeteer in tandem with tools like Multilogin to solve fingerprinting issues.
Let’s get started.

Why Multi-Session Automation Breaks at Scale

Anyone who has tried to launch more than a handful of browser sessions has seen this happen:

Sessions crash
All accounts get banned
Playwright/Puppeteer freeze from memory overload
Proxies get rate-limited
Cookies leak between contexts

Detection systems flag everything as automation

Common root causes:
❌ Shared browser fingerprints
Playwright and Puppeteer produce extremely uniform fingerprints.
❌ Shared storage/cookies
Mixing accounts = immediate linkage → bans.
❌ Repeated IPs
Using the same proxy for multiple accounts triggers anti-fraud systems.
❌ Headless/browser automation flags
Default automation environments are easily detected.
❌ Memory overload
Chromium instances multiply RAM usage fast.
Scaling requires identity isolation + network isolation + resource isolation.

Identity Isolation: The Real Key to Multi-Session Stability
Every session must behave like a separate real user.
This means isolating:

Fingerprints
Cookies
Storage
IP
Timezone
Locale
Language
Device metrics
WebRTC
TLS/JA3 fingerprint

An important note:
Changing fingerprints randomly every session is also suspicious.
Stability > randomness.
This is why many devs launch their automation inside separate Multilogin profiles, because each profile has:

a persistent fingerprint
persistent local storage
its own proxy
its own identity
no cross-contamination

Playwright/Puppeteer handle automation. Multilogin handles identity.

Recommended Architecture for 10–100 Parallel Sessions

You need a distributed system, even if it starts on one machine.
High-Level Architecture

              +----------------------+
              |     Task Queue       |
              +----------+-----------+
                         |
  ----------------------------------------------------
  |                   |                     |

Task queue: (BullMQ, RabbitMQ, Redis, Kafka)
Workers: Nodes running Playwright/Puppeteer
Proxy router: Assigns 1:1 IP per identity
Storage: Separate directories per session
Identity provider: Could be Multilogin profiles

Playwright/Puppeteer Session Isolation Basics

Playwright (isolated context)

const { chromium } = require('playwright');

async function startSession(id, proxy) {
  const browser = await chromium.launch({
    headless: false,
    proxy: {
      server: proxy
    }
  });

  const context = await browser.newContext({
    storageState: `sessions/session-${id}.json`
  });

  const page = await context.newPage();
  await page.goto('https://example.com');

  // Save session state
  await context.storageState({ path: `sessions/session-${id}.json` });
}

Puppeteer (persistent session)

const puppeteer = require('puppeteer');

async function startSession(id, proxy) {
  const browser = await puppeteer.launch({
    headless: false,
    args: [
      `--proxy-server=${proxy}`
    ],
    userDataDir: `./sessions/${id}`
  });

  const page = await browser.newPage();
  await page.goto('https://example.com');
}

Notice:

Each session has its own storage directory

Each session has its own proxy

This is the bare minimum.

But Playwright/Puppeteer still produce detectable fingerprints.

Fingerprint Challenges With Playwright/Puppeteer

Playwright/Puppeteer-generated environments share:

identical fonts

identical canvas metrics
identical WebGL fingerprints
identical audioContext
identical WebRTC behavior
identical headless markers
identical TLS/JA3 signatures

Bots get flagged quickly.

The fact that they're the exact same is what makes them super easy to detect. An anti-bot system doesn't need your script to do something that outright fails; it just needs to detect one thing that seems off. If every single session looks like it's coming from the exact same machine, with the exact same internals, the exact same browser render pipeline, and the exact same network fingerprint, the sites will aggregate and block your automation within seconds. This is the reason developers can't scale more than a handful of Playwright/Puppeteer sessions before getting banned/blocked.

Tools like Multilogin solve this by launching Playwright or Puppeteer inside an isolated browser profile with:

real-world fingerprints
dynamic canvas
proper WebRTC masking
native-like WebGL
stable identity per session
built-in proxy handling

In automation:
Playwright/Puppeteer = your hands
Multilogin = your identity

In other words: Playwright/Puppeteer handle the automation logic, while Multilogin handles the digital identity that keeps each session independent.

Proxy Distribution for 10–100 Sessions

const proxies = [
  "jp-residential-001.proxy.com:8000",
  "jp-residential-002.proxy.com:8000",
  ...
];

function getProxyForSession(id) {
  return proxies[id % proxies.length];
}

Rules:

Always use 1 IP = 1 account
Never reuse IPs across identities
Prefer residential or mobile
Keep the proxy location consistent with timezone

Conclusion

Running 10, 50, or 100 Playwright/Puppeteer sessions is not about writing more code — it’s about managing identity, fingerprints, and infrastructure correctly.

If every session:

has its own identity
has its own proxy
has persistent storage
has stable fingerprints
is isolated properly …scaling becomes predictable.

This is why many developers automate inside Multilogin profiles the tool provides the identity isolation layer that Playwright/Puppeteer can’t, while the automation framework handles scripting and workflows.

Automation breaks when identities mix.
Automation scales when identities stay separate.

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