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

# Institutional API reference

> OTC, Custody, and Prime — pick the service and protocol for your workflow

Kraken's Institutional APIs cover three services. **OTC** and **Custody** are single-protocol; **Prime** offers REST, FIX, and WebSocket against the same accounts.

<Note>
  All Institutional APIs require onboarding through your Account Manager. See the [Institutional overview](/institutional/guides/overview) for use cases and access requirements.
</Note>

## OTC

Off-book block trading with negotiated quotes — request, accept, and reconcile large trades.

<CardGroup cols={1}>
  <Card title="OTC REST" icon="code" href="/institutional/api-reference/otc-rest">
    Quote requests, active and historical quotes, exposures.
  </Card>
</CardGroup>

## Custody

Programmatic management of segregated wallets, deposits, withdrawals, and reconciliation.

<CardGroup cols={1}>
  <Card title="Custody REST" icon="code" href="/institutional/api-reference/custody-rest">
    Vaults, balances, deposit/withdraw methods, custody tasks and activities.
  </Card>
</CardGroup>

## Prime

Institutional brokerage with three protocol surfaces against the same Prime accounts and keys.

<CardGroup cols={3}>
  <Card title="Prime REST" icon="code" href="/institutional/api-reference/prime-rest">
    API-user management, key lifecycle, and settlement batches.
  </Card>

  <Card title="Prime FIX" icon="terminal" href="/institutional/api-reference/prime-fix/logon">
    FIX 4.4 order management and market data — co-located, deterministic.
  </Card>

  <Card title="Prime WebSocket" icon="bolt" href="/institutional/api-reference/prime-websocket/authentication">
    Real-time order events, balances, exposures, and RFQ flows.
  </Card>
</CardGroup>

## Not sure where to start?

<CardGroup cols={2}>
  <Card title="Custody REST authentication" icon="lock" href="/institutional/guides/custody-rest-auth">
    Authenticate requests to the Custody REST API.
  </Card>

  <Card title="Prime WebSocket authentication" icon="lock" href="/institutional/guides/prime-websocket-auth">
    Authenticate and subscribe to Prime WebSocket channels.
  </Card>
</CardGroup>