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

# API conventions

> Identifiers, data formats, and request limits shared across the Hop API

These conventions apply across the API. Endpoint references document their request fields, responses, and any additional requirements.

## Identifiers

Objects carry an external ID made up of a short prefix, an underscore, and 24 lowercase alphanumeric characters, for example `acct_9f2a7c1e6a2b4f3c9b8d2e5a`.

| Prefix | Object | Prefix | Object |
| - | - | - | - |
| `cus_` | Customer | `va_` | Virtual account |
| `acct_` | Account | `vag_` | Virtual account group |
| `aap_` | Associated person | `agr_` | Agreement |
| `bene_` | Beneficiary | `doc_` | Document |
| `dest_` | Payout destination | `req_` | Onboarding requirement key |
| `po_` | Payout | `wal_` | Wallet |
| `pi_` | Payin | `fxq_` | FX quote |
| `trf_` | Transfer | `fxt_` | FX trade |
| `fi_` | Deposit instruction, dedicated account | `wh_` | Webhook endpoint |
| `di_` | Deposit instruction, shared account | `whn_` | Webhook notification |
| `ak_` | API key | | |

For deposit instructions, `di_` prefixes the instruction's `id`. The required payment reference is returned separately in `memo`; copy that value exactly when sending funds. Use the returned `memo` to determine whether a reference is required. See [Deposit Flows](/fx/guides/deposit-flows).

## Data formats

* **Amounts** are JSON strings, not numbers, and are returned at the precision of their currency. See [Handling currencies](/fx/guides/handling-currencies).
* **Timestamps** are ISO 8601, UTC. Objects carry `created` and `updated`, plus `created_by` and `updated_by`.
* **Audit actors:** `created_by` and `updated_by` carry the literal string `hop_admin` when Hop made the change.

## Request limits

Request bodies are capped at 1 MB, except [Update Account](/fx/api-reference/accounts/update-account-identity) and [Upload Document](/fx/api-reference/virtual-account-groups/upload-document), which accept 21 MB because they carry base64 documents. Over the limit returns `413` `REQUEST_TOO_LARGE` with `details.max_bytes`.

For per-key request frequency limits and `429` responses, see [Rate limits](/fx/api-reference/errors#rate-limits).

## Request IDs

`X-Request-ID` is an optional request header, echoed in every error as `request_id`. Omit it and Hop generates a UUID. Log `request_id` and include it when contacting support.

## Deleted resources

Deletes are soft. A deleted object stops appearing in reads and returns `404` on any further call.