> ## Documentation Index
> Fetch the complete documentation index at: https://docs.gate.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Institution Headers

> Explains the required headers for institution APIs and how to use X-GatePay-On-Behalf-Of.

Institution APIs include dedicated institution endpoints and a full set of institution merchant APIs exposed under institution-prefixed paths. For the signature algorithm and verification rules, see [Security and Signature](/global/api-reference/version/100/en/common/securityAndSignature).

## Request headers

| Header | Required | Description |
| - | - | - |
| X-GatePay-Certificate-ClientId | Yes | The clientId assigned when the merchant registers an application in the Gate merchant console |
| X-GatePay-Timestamp | Yes | Millisecond timestamp; the difference from server time must not exceed 30 seconds. |
| X-GatePay-Nonce | Yes | Random string. Recommended length within 32 characters, composed of digits and letters |
| X-GatePay-Signature | Yes | Request signature. GatePay uses this signature to verify whether the request is valid |
| X-GatePay-On-Behalf-Of | Required on selected institution APIs | The initiating account ID for the current request. Institution merchant APIs typically use the target sub-account ID; charge and transfer APIs can use either an institution account ID or a sub-account ID. It is not used by the account APIs or the fee-setting APIs. |

## Endpoints that do NOT require X-GatePay-On-Behalf-Of

The following dedicated institution APIs are **institution master-account–scoped**. Do **not** send **X-GatePay-On-Behalf-Of** in the request header; the first four common headers are sufficient:

**Accounts**

* Create sub-account
* Query sub-account
* List sub-accounts (paginated)

Charge APIs, transfer APIs, and institution merchant APIs **must** include **X-GatePay-On-Behalf-Of**. Institution merchant APIs typically use the target sub-account ID; charge and transfer APIs can use the initiating account ID for the current transaction (either an institution account ID or a sub-account ID). Account APIs and fee-setting APIs do not use this header.


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