Stack Depth Protection

JavaScript recursive stack depth is a privacy-relevant signal. BotBrowser controls stack depth values through the --bot-stack-seed flag.

Prerequisites

BotBrowser installed. See Installation Guide.
A profile file (.enc for production).

Overview

JavaScript recursive call stack depth is a privacy-relevant signal that varies by platform and cannot be controlled through JavaScript injection. BotBrowser protects this surface through the --bot-stack-seed flag (ENT Tier2).

Quick Start


chromium-browser \
  --bot-profile="/path/to/profile.enc"

Start with this launch to establish a clean baseline before adding extra overrides.

How BotBrowser Controls Stack Depth

The --bot-stack-seed flag provides three modes of stack depth control:

Value	Behavior
`profile`	Use the exact stack depth values stored in the profile, matching the reference device.
`real`	Use the native stack depth of the host system. Useful when running on the same platform as the profile target.
`<integer>` (1-UINT32_MAX)	Per-session depth variation. Each seed produces a different but stable value. Same seed = same depth across sessions.

Profile Mode


chromium-browser \
  --bot-profile="/path/to/profile.enc" \
  --bot-stack-seed=profile

Real Mode


chromium-browser \
  --bot-profile="/path/to/profile.enc" \
  --bot-stack-seed=real

Seed Mode


chromium-browser \
  --bot-profile="/path/to/profile.enc" \
  --bot-stack-seed=12345

Coverage Across Contexts

BotBrowser controls stack depth across all three execution contexts:

Main thread: The primary JavaScript execution context
Web Workers: Background thread contexts
WASM: WebAssembly execution stack

The controlled values maintain realistic ratios between contexts, matching what the target platform would produce.

Common Scenarios

Keeping profile-consistent depth across hosts

Use --bot-stack-seed=profile when your profile should stay aligned across macOS/Linux/Windows deployment hosts.

Controlled per-session variance

Use integer seed mode (--bot-stack-seed=12345) to keep runs reproducible per seed while avoiding one fixed depth for every session.

Verifying multi-context behavior

Compare main-thread and Worker depth together when validating changes. A realistic ratio between contexts is often more important than one absolute number.

Effect Verification

To verify protection is active:

Launch BotBrowser with a profile and visit a fingerprint testing site such as BrowserLeaks or CreepJS .
Confirm that the reported stack depth values match the profile configuration, not the host machine.
To verify reproducibility, launch two sessions with the same --bot-stack-seed and confirm that the stack depth output is identical across main thread, Web Workers, and WASM contexts.

Troubleshooting / FAQ

Problem	Solution
Stack depth is lower than expected on all contexts	Confirm `--bot-stack-seed` mode is what you intended (`profile`, `real`, or integer seed).
Main thread and Worker depths look inconsistent	Re-check that context setup and runtime flags are applied before page scripts execute.
Depth varies across sessions unexpectedly	Avoid mixing seed mode and real mode between runs. Keep a fixed seed for reproducible validation.

Next Steps

Performance Fingerprinting. Control timing-based fingerprint signals.
CPU Core Scaling Protection. Constrain Worker parallelism to match claimed core count.
CLI Flags Reference. Complete flag documentation including --bot-stack-seed.

Related documentation: Advanced Features: Stack Depth Control | CLI Flags

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