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

# Reference

> The rules every OpenType API request follows: conventions, request ids, scopes, errors, problem codes, limits, and the changelog.

This tab is the lookup layer of the documentation. Come here when you already know what you are building and need an exact answer: the format of an id, the scope a route demands, what a status code means, how large a question set may be, or what changed in the API. The guides explain how to do things; these pages state the rules they rely on.

<CardGroup cols={2}>
  <Card title="Conventions" icon="ruler-combined" href="/reference/conventions">
    Base URL, JSON rules, id formats, timestamps, time windows, micro-USD amounts, and CORS.
  </Card>

  <Card title="Request ids" icon="fingerprint" href="/reference/request-ids">
    The `x-request-id` header: sending your own, reading it back, and quoting it when you report an issue.
  </Card>

  <Card title="Scopes" icon="key" href="/reference/scopes">
    Which scope each route demands, and which scopes each organization role holds.
  </Card>

  <Card title="Errors" icon="triangle-exclamation" href="/reference/errors">
    The error envelope, what each HTTP status means, plain-text rejections, and how to retry safely.
  </Card>

  <Card title="Problem codes" icon="list" href="/problems">
    Every error code, its HTTP status, whether a retry can help, and the page that explains it.
  </Card>

  <Card title="Limits" icon="gauge-high" href="/reference/limits">
    Body size, question and schema bounds, deadlines, spend ceilings, list sizes, and period quotas.
  </Card>

  <Card title="Changelog" icon="clock-rotate-left" href="/reference/changelog">
    Dated changes to the API contract.
  </Card>

  <Card title="API reference" icon="square-terminal" href="/api-reference/introduction">
    Every endpoint, generated from the OpenAPI document the server publishes.
  </Card>
</CardGroup>

## At a glance

|                |                                                                                                                     |
| -------------- | ------------------------------------------------------------------------------------------------------------------- |
| Base URL       | `https://api.opentype.dev`, every route under `/v1`                                                                 |
| Authentication | `Authorization: Bearer otsk_...` on every `/v1` route                                                               |
| Bodies         | JSON, snake\_case field names, unknown fields refused, 4 MiB at most on runs and router selections, 1 MiB elsewhere |
| Money          | integers in micro-USD: 1,000,000 is \$1                                                                             |
| Timestamps     | `YYYY-MM-DDTHH:MM:SSZ`, UTC, second precision                                                                       |
| Errors         | `{"error": {"code", "message", "request_id"}}`; branch on `code`                                                    |
| Request id     | `x-request-id` on every response                                                                                    |
| Model          | Neon 1.1, API ids `neon-1.1` and `neon-latest`                                                                      |

## Related

* [Quickstart](/getting-started/quickstart) - send your first run before you need the rules.
* [Error handling](/guides/error-handling) - turn the error rules into client code.
* [Scopes and roles](/security/scopes-and-roles) - choose the least privilege a key needs.
* [API reference](/api-reference/introduction) - request and response schemas for every endpoint.