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Subscription link

Last updated October 8, 2026

A profile in Cosmos Client is an https://… link. The app requests the configuration from it and then keeps it up to date on its own.

Request

GET /sub/<token> HTTP/1.1
Host: example.com
User-Agent: CosmosClientApp/1.0.0 (iOS; sing-box 1.14.2)
  • https only — for the link and for redirects.
  • User-Agent — CosmosClientApp/<app version> (<OS>; sing-box <core version>). The server can use it to return a sing-box configuration for the right core version.

Response

  • Body — a sing-box configuration in JSON.
  • The X-Meta header — expiry, traffic, country and links (X-Meta header). Optional: without it the profile works, but the app won’t show this data.

Errors

  • 404 — the link isn’t found.
  • 403 with an X-Meta header — the subscription has expired or access is closed.
  • 5xx — a temporary server error: the app connects with the last saved configuration and retries later.

Updates

The app requests the configuration again from time to time, and the user can also refresh it manually. A changed configuration is applied without turning VPN off.