Configuration

Every setting the daemon reads: the four layers and which wins, the TOML blocks with their defaults, and the environment variables that override them.

Last updated Sep 20, 2026

Four layers, later ones win:

built-in defaults
a TOML file, passed with --config
environment variables
command-line flags

Every field has a default, so a daemon with no configuration at all starts and serves.

The top level

Key	Default	What it does
`bind_addr`	`127.0.0.1:8787`	The native API: REST, MCP over HTTP, the CDP WebSocket. Non-loopback requires `[tls]`.
`adspower_bind`	off	The AdsPower adapter. Loopback only, and off until you set it.
`data_dir`	`%ProgramData%\Scalebrowser`	Database, engines, profile directories, the at-rest key.
`engines_dir`	follows `data_dir`	Set it only to split the tree deliberately. Once set, it stops following.
`profiles_dir`	follows `data_dir`	Same.
`bearer_token`	generated on first start	The token clients send.
`webui_dir`	the embedded bundle	Serve the management interface from a directory instead.
`ja4t_reflector_url`	none	An endpoint that reports the TCP fingerprint it saw. Fetched through the proxy during a check, which is the only way to learn the exit device's fingerprint.
`error_reporting`	`false`	Crash reports. Off by default: on an anti-detect product, telemetry nobody asked for is a surprise that costs the relationship.
`error_dsn`	none	Where they go. Empty disables reporting whatever the flag says.
`log_json`	`false`	Machine-readable log lines. On where something parses them, off where a person reads them.

`[secret]`

Where the at-rest master key comes from. One of the two:

Key	What it does
`key_env`	Name of the environment variable holding it.
`key_file`	Path to a file holding it.

`[capacity]`

Hard limits, so a launch is refused rather than the host running out of memory.

Key	Default	What it does
`max_concurrent`	`64`	Browsers on this machine at once.
`ram_budget_mb`	`24576`	Memory the pool may use.
`vram_budget_mb`	none	Video memory, when you want a ceiling on it.

Three limits apply to a launch and the strictest wins: these two, and the host's measured free memory. Exceeding any of them is error 4003.

`[tls]`

Key	What it does
`cert_path`	PEM certificate chain.
`key_path`	PEM private key.

Required for a non-loopback bind, optional on loopback, and honoured there too if set.

`[mcp]`

Everything here is decided server-side. No tool call can widen the catalog or leave read-only mode.

Key	Default	What it does
`profiles`	`["core"]`	Which tool profiles are served.
`read_only`	`false`	Mutating tools are neither listed nor executed.
`lease_ttl_secs`	`900`	How long a reservation lives by default.
`lease_ttl_max_secs`	`14400`	Ceiling on what a caller may ask for. Four hours.
`url_allowlist`	`[]`	Exceptions to the `open_page` address rule. Exact hosts or `host:port`.
`artifact_quota`	`256`	How many artifacts are kept. One store per daemon, shared by every profile.
`artifact_max_bytes`	24 MiB	Ceiling on one artifact.
`artifact_ttl_secs`	`14400`	Retention. Matches the lease ceiling, so an artifact from the start of a long run is still there at the end.
`allowed_hosts`	`[]`	Extra `Host` values the MCP transport accepts, on top of loopback and the configured bind.
`snapshot_full_every`	`5`	Force a full page map every N steps. `0` disables it.
`transcribe_command`	`[]`	Your program for audio challenges. One argument in, text out.
`inbox_command`	`[]`	Your program for non-IMAP inboxes, such as an SMS service.
`inbox_require_proxy`	`false`	Refuse an inbox read that would leave over this machine's own connection.

url_allowlist empty is the safe state. Empty means open_page permits public http and https only: no file:, no loopback, no private or link-local networks, no cloud metadata address. Every entry you add is a door into your own network that an agent can walk through.

`[observability]`

Key	Default	What it does
`sample_interval_ms`	`3000`	Cadence of the background sampler behind `GET /v1/metrics`.
`enable_prometheus`	`false`	The opt-in scrape endpoint.
`prometheus_bind`	`127.0.0.1:9464`	Its listener. Unauthenticated plaintext; keep it on loopback.

`[runs]`

Key	Default	What it does
`shots`	`true`	Keep a still per step in the activity trail.
`shots_max_gb`	`20`	Disk ceiling for them.
`shots_max_age_days`	`30`	Retention.
`page_watcher`	`true`	Follow what the bound tab is showing.

`[exit]`

The exit-address rule.

Key	Default	What it does
`enabled`	`true`	The whole rule.
`probe_url`	`https://probe.scalebrowser.net/v1/addr`	Where the address is measured.
`neighbour_hard`	`false`	Treat two addresses in one IPv4 `/24` as a collision, not advice.
`heartbeat_secs`	`30`	Keep-alive beat, where a provider documents an idle cut-off.
`check_secs`	`120`	Address check.
`max_draws`	`5`	How many session tags a start may try before refusing with `4013`.

`[strict]`

What geo_mode = strict_expected does per check, beyond the country. See coherence.

Each key takes one of three words: required refuses the start with error 4002, advisory lets it start and records the finding, off skips the check.

What required refuses depends on the check, and the difference is deliberate. For timezone and observation it means "no start without this evidence", so a check that could not run refuses too. For exit_class it means "a proven datacenter refuses": an exit nobody can place still starts, because without the optional network dataset an ordinary home connection cannot be recognised as one, and refusing on that would turn away every normal proxy.

Key	Default	What it checks
`exit_class`	`required`	A datacenter or hosting exit. Anti-bot systems score the network before any JavaScript runs, so this is the one finding worth a refused start on its own.
`timezone`	`advisory`	The zone the geo endpoint reports for the exit, against the profile's. Reported, never measured, so a provider that mislabels a city would otherwise lock the profile out.
`observation`	`advisory`	The JA4T observation of the exit. Without `ja4t_reflector_url` there is nothing to observe and the verdict stays unobserved.

The exit country is not in this table. It is what strict_expected promises, it stays fail closed, and no key weakens it.

Setting observation = "required" makes a reachable reflector part of running this installation: an exit nobody observed then does not start.

`[sync]` and `[remote]`

Profile sync and remote access have their own blocks. Both have a switch in the management app, and for remote access that switch is the one to use: the daemon reads it on every beat, so it takes effect without a restart.

Environment variables

Every one of these overrides the TOML.

Variable	Sets
`SCALEBROWSER_BEARER_TOKEN`	The API token clients send.
`SCALEBROWSER_MASTER_KEY`	The at-rest key.
`SCALEBROWSER_API_TOKEN`	The pairing token for this machine.
`SCALEBROWSER_DATA_DIR`	`data_dir`.
`SCALEBROWSER_ENGINES_DIR`	`engines_dir`.
`SCALEBROWSER_PROFILES_DIR`	`profiles_dir`.
`SCALEBROWSER_BIND_ADDR`	`bind_addr`.
`SCALEBROWSER_ADSPOWER_BIND`	`adspower_bind`. Takes the word `off`.
`SCALEBROWSER_WEBUI_DIR`	`webui_dir`.
`SCALEBROWSER_CONTROL_PLANE_URL`	Where the account lives.
`SCALEBROWSER_MCP_PROFILES`	`[mcp] profiles`, comma separated.
`SCALEBROWSER_MCP_READ_ONLY`	`[mcp] read_only`.
`SCALEBROWSER_ENABLE_PROMETHEUS`	`[observability] enable_prometheus`.
`SCALEBROWSER_PROMETHEUS_BIND`	`[observability] prometheus_bind`.
`SCALEBROWSER_SAMPLE_INTERVAL_MS`	`[observability] sample_interval_ms`.
`SCALEBROWSER_ERROR_DSN`	`error_dsn`.
`SCALEBROWSER_ERROR_REPORTING`	`error_reporting`.

Two more are about the host rather than the daemon: SB_HOST_GPU_CLASS and SB_HOST_GPU_VENDOR skip the boot GPU probe.

Never set SB_HOST_GPU_CLASS on a machine you are actually running profiles on, unless you also set the vendor. The skipped probe never learns which GPU family the host has, and the profile can then ship a GPU string from the wrong one, which is a contradiction a page finds in one comparison.

CLI reference: the flags and subcommands.
Troubleshooting: what these settings look like when one is wrong.
MCP server: what [mcp] does to an agent.

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