# ID in the subscription

> Three ways to pass your provider ID to the app: a response header, a line in the subscription body, or the link fragment.

The app recognises your subscription by the **provider ID**: 10 lowercase Latin letters and digits, shown in the
cabinet's overview. Any of the three ways below will do. If several are present, the app takes the first one in this
list.

## Response header

The best way, if your panel supports custom headers:

```
flowlock-provider: k7m2x9q4bd
```

In Remnawave: “Subscription settings” → “Additional response headers” (`customResponseHeaders`), name
`flowlock-provider`, value: your ID. Other clients skip an unknown header, so there is no need to send it to FlowLock
only.

## Line in the subscription body

For link-list and base64 subscriptions (in base64, inside the encoded text), within the first 50 lines. Other clients
treat such a line as a comment:

```
#flowlock-provider: k7m2x9q4bd
vless://…
vless://…
```

Spaces are allowed between `#`, the name and the colon, and the name is case-insensitive. Lines longer than 1024 bytes
are skipped. JSON subscriptions (Xray, sing-box) have no such line: use the header or the fragment.

## Subscription link fragment

When you can change neither the headers nor the body, add the ID to the link you give the user:

```
https://sub.example.com/abc123#My VPN?flowlock-provider=k7m2x9q4bd
https://sub.example.com/abc123#flowlock-provider=k7m2x9q4bd
```

Browsers and apps don't send the fragment (everything after `#`) to the server, so the panel never sees it.

## Good to know

- The ID isn't a secret: without a [verified domain](https://flowlock.cc/en/docs/domains.md) it unlocks nothing.
- Case doesn't matter: `K7M2X9Q4BD` = `k7m2x9q4bd`.
- The app remembers the ID from the last successful subscription refresh. Remove the ID from the response and the
  subscription is ordinary again.
- FlowLock doesn't read Happ's `providerid`: FlowLock has its own ID. Add `flowlock-provider` next to it.

## How to check

Once the ID is in the subscription and the domain is verified, refresh the subscription in FlowLock. Within a minute
the device appears in the cabinet under “Devices”, and your contacts appear on the subscription card. If a person
turned off “Tell the provider I'm connected”, their device won't show up in the statistics: that is their right (see
[“Privacy”](https://flowlock.cc/en/docs/privacy.md)).