# HTTP status code: 503 Service Unavailable

Independent and unofficial. Not affiliated with or endorsed by any broker or platform named here. Educational only: nothing here is advice, and nothing here recommends a broker or a trade.

This is the markdown version of https://openbrokerapi.com/errors/http/503, written from the same records as that page.

Risk warning: CFDs and spread bets are complex instruments and come with a high risk of losing money rapidly due to leverage. You can lose money on these products, and each provider publishes its own loss figure under FCA rules. You should consider whether you understand how they work and whether you can afford to take the high risk of losing your money. Automated and API trading can amplify losses through bugs, connectivity failures and runaway orders.

As text you can copy:

```
503 Service Unavailable
```

- Kind: Status code
- Read from: [RFC 9110, HTTP Semantics, section 15.6.4](https://www.rfc-editor.org/rfc/rfc9110.html#section-15.6.4)
- Status: verified. Source: [rfc-editor.org](https://www.rfc-editor.org/rfc/rfc9110.html#section-15.6.4), checked 2026-10-09.

## What does 503 Service Unavailable mean in HTTP?

The server cannot handle the request for now because of a temporary overload or scheduled maintenance, which is likely to ease after some delay. The server may send a Retry-After header to suggest how long to wait.

## What it means in trading API work

Maintenance windows, outages and overload show up as 503. Whether a market is open is a different matter: an API can be up while a market is closed, and that is normally reported through the API's own code.

This part is this site's own explanation, written for people learning to call a trading API. It is not part of the source cited above and it describes no particular broker.

## What should I do about 503 Service Unavailable?

Honour Retry-After if the reply carries it, otherwise wait and retry with growing gaps. Check the provider's status page. For an order request, read open orders and positions before sending it again.

This page is an independent explanation in plain words. The definition itself is in [the source it was read from](https://www.rfc-editor.org/rfc/rfc9110.html#section-15.6.4), which is the authority if the two ever differ.

## Where to go next

- [Everything decoded for HTTP](https://openbrokerapi.com/errors/http)
- [Getting started with API trading](https://openbrokerapi.com/guides/getting-started-with-api-trading): What an API is, what you need and how to make a first call safely.
- [Brokers](https://openbrokerapi.com/brokers): The record for each broker: access, limits, endpoints and error codes.
- [Platform APIs](https://openbrokerapi.com/platforms): APIs that belong to trading software offered by many brokers.
- [Error codes](https://openbrokerapi.com/errors): What each error means, and the fix where the source gives one.

## Licence and how to cite

The records behind this page are all rights reserved. This file is the page itself, at its own address, in another format. It is not part of the CC BY 4.0 downloads listed at https://openbrokerapi.com/data. Quote from it with a link to the page.

Cite as: HTTP status code: 503 Service Unavailable. Broker API Hub, https://openbrokerapi.com/errors/http/503, newest check 2026-10-09.

Where you rely on a single figure, cite the source and the checked date printed beside it as well. Where this page and a broker's own documentation differ, the documentation wins.