Shared Open API application & rate limits

By default every user registers their own cTrader Open API application under Settings → Open API. A white-label operator (typically a cTrader broker or reseller) can instead ship one shared Open API application for all users — nobody registers their own; everyone authorizes their accounts through the operator's single app.

Two ways to provide the shared application

The shared application is provisioned either from deployment config or from the owner settings UI (the owner-set value wins). Provide it once and shared-mode turns on for everyone.

1. Deployment config (seeded on startup)

"App": {
  "OpenApi": {
    "PublicBaseUrl": "https://cmind.yourbroker.com",   // canonical public URL of THIS deployment
    "SharedApp": {
      "Enabled": true,
      "Name": "YourBroker Open API",
      "ClientId": "1234_abcd...",
      "ClientSecret": "…"                                // encrypted at rest; never logged
    }
  }
}

On startup the app seeds one shared application owned by the owner account (idempotent — it never overwrites an owner-edited runtime value, and re-seeding is a no-op).

2. Owner settings (runtime, no redeploy)

Settings → Open API (owner only) shows two things: a Your Open API application section — the owner registers, edits, and authorizes their own per-user app exactly like any user (available while no shared app is configured) — and a Deployment shared application card to add / edit / delete the shared app, with the redirect URL displayed for copy-paste. Changes take effect for new authorizations immediately. Once a shared app is configured it supersedes the owner's own app, and the Your Open API application section switches to a notice that accounts now authorize through the shared app.

The redirect URL (register this in cTrader)

Every cTrader Open API application registers one redirect URL — the same single value for the shared app and for any per-user app:

{your deployment URL}/openapi/callback

for example https://cmind.yourbroker.com/openapi/callback.

• The app displays the exact value on the Open API settings page (with a copy button) — paste it into the cTrader partner portal when you create the Open API application.
• It is composed from App:OpenApi:PublicBaseUrl so it stays stable behind a reverse proxy / CDN; when that is unset it falls back to the inbound request host.
• The invite vs normal-user experience differs only in where the user lands after the callback (their accounts list vs an "accounts added" confirmation) — the registered redirect URL is unchanged.

What users see under shared mode

When a shared application exists:

• Users get no option to register their own Open API application — the settings page shows "Open API is managed by your provider" and an Authorize accounts button that uses the shared app.
• Any pre-existing personal applications are removed; their authorized accounts are re-pointed to the shared app and must be re-authorized (their old tokens were issued under a different client id). Attempting to create a personal app returns a "managed by your provider" error.

Client rate limits (per message type)

The client paces outbound cTrader Open API messages so a burst never trips a server-side rate-limit block. Limits are per message type, matching the cTrader Open API docs:

Category	What it covers	Default
General	trading + read messages (orders, symbols, account queries)	45 msg/s
HistoricalData	trendbar / tick-data requests (throttled harder by cTrader)	5 msg/s

A historical-data request counts against both its own bucket and the general bucket. Heartbeat and authentication messages are never paced. Messages queue and drain at the available rate — nothing is dropped and order is preserved.

Tune them if your broker negotiated higher cTrader limits, or set a category to 0 to disable pacing entirely (unlimited):

• Config: App:OpenApi:RateLimits:General / App:OpenApi:RateLimits:HistoricalData (msgs/sec).
• Owner settings: the Client rate limits card on Settings → Open API (owner override wins, applies to new connections / on reconnect).